Graduate Student Master's Thesis 2009
The reports are not to be duplicated or printed without written consent by the author and RES.
Aluminum Alloy Drill Pipe in Geothermal Drilling [PDF]
Technical and Economical Opportunities
© Erin Rebecca Anderson (Geothermal Energy Specialization)
Abstract
The purpose of this investigation is to determine the application opportunities of aluminum alloy drill pipe (ADP) in geothermal drilling environments. The Geothermal Energy industry is at the tipping point of the global energy mix. Geothermal offers the benefits of other clean, sustainable energies such as low emissions but also boasts a small environmental footprint, base-load power, and widespread distribution as related to EGS applications. Additionally, with the improved development into ultra high energy extraction regions, the geothermal drilling industry is under high demand and is being tested to drill deeper, faster, and at reduced costs in order to make geothermal competitive economically and to satisfy energy demands. The achievement of greater drilling depths requires the advancement of the drilling industry to address limitations in the weight capacity of the drill rigs and the temperature limitations of the drilling components. Aluminum alloy drill pipes (ADP), sometimes referred to as Lightweight Aluminum Drill pipes (LADP) have been used in the drilling industry in Russia for many years. Due to ADP’s lightweight and high strength to weight ratio there are several advantages over conventional steel pipe. These advantages include the use of larger diameter drill pipe with thicker walls which increase annular flow; reduced pressure loss inside the drill pipe, resulting in smaller pump requirements; reduced derrick loads and hook loads due to reduced weight per length compared to steel and increased buoyancy effects in drilling fluids, resulting in smaller rigs or greater depth penetrations with current rigs; and reduced stresses in a number of drilling design parameters. The application ranges of ADP utilization will be studied in regards to temperature limitations, critical buckling loads and strength of materials, geothermal fluid chemistry, drilling fluid pressure losses and hydraulics, load comparisons, tool joint bonding, and economical cost analysis.
Exploration of Geothermal Systems with Petrel Modeling Software [PDF]
© Dorottya Bartucz (Geothermal Energy Specialization)
Abstract
In this thesis work an area located in Hungary was examined in order to localize the most promising site for geothermal water extraction for use in electricity production or in direct heat utilization systems.
Hungary is located in the central part of the Pannonian Basin. The geological evolution of the basin was favorable for the formation of low- and medium-enthalpy geothermal reservoirs throughout the country. These resources are already used in the balneology and agriculture sector. The utilization of the natural hot water in district heating systems and for domestic hot water supply has been developing fast in the recent years, while electricity generation from geothermal water is still in research phase.
A three-dimensional (3D) digital geological model of the area was created to support the localization of the best prospective site in the area of interest. For the model’s construction, eighteen two-dimensional (2D) seismic sections were used as input data. The Petrel geological modeling software, which was developed by Schlumberger Co, was used for data processing.
Three promising sites were designated in the studied area. Those sites were selected where the old deep and young shallower fractured zones cross each other by creating a locally extensional stress field. Due to the difficulties of the interpretation process the presence of the before mentioned requirements are very likely, but not certain, in the designated areas. Further exploration is crucial.
A comparison made between the computer supported analysis and the manual interpretation of hard copies of the seismic sections revealed that computer aided interpretation process lead to the recognition of more detailed tectonic structures in a relatively shorter time interval.
Hydrogen Fuel Cell Emergency Power System [PDF]
Installation and Performance of Plug Power GenCore 5B48 Unit
© Lech Birek & Stanisław Molitorys (Fuel Cell Systems & Hydrogen Specialization)
Abstract
Backup systems are crucial elements of modern electrical grids. They are used in places where an interruption in power supply can cause significant damage, e.g. in hospitals, banks or telecommunication towers. There are many solutions for how emergency power can be delivered. Hydrogen fuel cells are an emerging technology with great potential for the future. Fuel cells combine the advantages of batteries and diesel generators, and eliminate some of their significant disadvantages. They can work as long as they are supplied with fuel via a simple and efficient electrochemical reaction and at the same time they are quiet, produce no emissions and require minimum maintenance.
The aim of this thesis is to present the idea of hydrogen fuel cells as reliable backup power systems. The work consisted of two parts: one practical, the other theoretical. The first part includes the background of energy security, emergency power sources, fuel cell systems backup power market, as well as an introduction to fuel cell technology, principles of operation and hydrogen safety. The practical part of this project is focused on the Plug Power GenCore 5B48 fuel cell backup power unit, its description, installation, operation, safety precautions and performance characteristics.
The necessary hydrogen infrastructure was built according to safety codes and standards. The performance and reliability of the system was assessed. The system’s behavior was stable except for several minor problems during start-up which required intervention. The measured efficiency of the fuel cell stack and the whole system at the maximum available load of 1.65kW was 42.5% and 35.8% respectively. It was noted that the auxiliary load of the system has great influence on the overall performance of the system, especially at low output power. Noted fuel consumption was 13slm at 1kW and fuel utilization efficiency was estimated at around 99%. A cold start-up analysis was conducted and described based on the output data. During the first few minutes of operation the system required additional power to warm the fuel cell stack. The transition analysis focused on the ability of the system to provide power in case of a sudden outage. It was working well with batteries, as the fuel cell needed approximately 15 seconds to be ready to completely take over the power demand. Reliability and availability were assessed to be 96.8% and 79.9% respectively. It has to be pointed out that it was not possible to completely determine the system’s performance during some of the failure scenario and operation under different load because of the limitations of time and budget.
Biodiesel Production in Iceland [Restricted Access]
© Swietlana Borkowska (Biofuels & Bioenergy Specialization)
Abstract
The importance of increasing the global share of biofuels in transportation goes without saying. Iceland, where the consumption of fossil fuels is considerable, has a viable potential for introducing biodiesel in its otherwise exceptional renewable overall energy portfolio.
In this study, a full picture of the possibilities of biodiesel production in Iceland was provided. After the theoretical introduction of all major aspects of a biodiesel economy, an assessment of its applicability in Iceland was performed.
A survey of potential feedstocks was performed. It was concluded that in a short term perspective, a small scale production (300-2,000 tons/yr) can be carried out using domestically available waste raw material, and full scale production (15,000-80,000 tons/yr) will depend on imported feedstock.
After laboratory research, including waste vegetable oil (WVO), the main domestic feedstock currently available, the recommendation for the production process of a small production plant was made. It includes acid esterification of free fatty acids (FFA) followed by alkali transesterification and methanol recovery from the reacted mixture. At this stage, distillation of crude FAME was suggested, however further research is necessary.
The full scale production could substitute 8%-44% of the fossil diesel fuel needs for transportation and machinery. The estimated production costs in a full scale biodiesel plant, 0.63-0.76 EUR/L, are within the European average.
Fungi tar degradation [PDF]
Possible application for micro-scale slow pyrolysis rotary kiln
© Petra Božič (Biofuels & Bioenergy Specialization)
Abstract
When gas is cleaned in the process of slow pyrolysis in small-scale applications, water scrubbing is the most commonly used technology. After gas cleaning the tar and water vapors are trapped in the water, which is used for scrubbing. This waste water consists of condensed water vapors and two fractions of tar (water soluble and heavy tar). The product of this slow pyrolysis process is considered waste. None of the tar fractions are adequate for direct use in co-firing technologies. First it (water soluble tar fraction) contains too much water and later in the heavy tar there is not a sufficient quantity. The percentage of tar yielded from the slow pyrolysis process is not sufficient to be distilled in order to chemically clean components for further industry use, but that is the case in fast pyrolysis. That is why it is treated as chemical waste and needs to be disposed properly, which is a costly process. In order to reduce this cost a bioremediation method of fungi tar degradation has been examined. Fungi have a more potent enzyme system and are therefore far more appropriate for tar degradation than bacteria.
3D Modeling of Geothermal Reservoirs [PDF]
Case Study from Subtatric Basin in Western Carpathians, Slovakia
© Lucia Hlavácová (Geothermal Energy Specialization)
Geothermal energy is a potential renewable energy source that should be taken into account by the Slovak government. To aid geothermal exploration, 3D modeling is a very useful tool. The objective of this project was to model Poprad basin and the northern part of Hornad basin, in the Inner Carpathian system in Slovakia, to assess future prospective geothermal areas. These two are considered active geothermal areas. The main aquifers are built by Triassic carbonates – dolomites and limestones of Choc and Krizna nappe. In the central part of the Poprad basin, on the basis of seismic interpretation, Choc nappe thicknesses from 200 to 1100 m were obtained. Larger nappe thicknesses from 1200 to 1500 m were obtained on the east and southeast part of the studied area. The average value of the temperature gradient reaches 32.6 – 34.5° C/km and the average value of the heat flow density was estimated on 67mW/m2. Temperatures on the top of the Pre-Paleogene basement reach 50 – 85° C. In this work the geologic structure of the Gerlachov area, which is situated in the northwestern part of Poprad Basin, was also interpreted. From a geothermal point of view the formations with the most potential are Mesozoic units represented by Choc and Krizna Nappes underlying Paleogene rocks. Based on the geologic composition of Choc Nappe, the existence of very good conditions for a geothermal water reservoir can be expected. Krizna Nappe has less positive conditions for geothermal waters exploitation. General discharge of groundwater in Choc Nappe should be more than 22 l.s-1. The temperature in Choc Nappe is between 35 and 45° C.
Risk Management and Contingency Planning for Well IDDP-1 [PDF]
© Sebastian Homuth (Geothermal Energy Specialization)
Abstract
The Icelandic Deep Drilling Project (IDDP) is a research program designed to evaluate improvements in the efficiency and economics of geothermal energy systems by harnessing Deep Unconventional Geothermal Resources (DUGR). The goal is to generate electricity from natural supercritical hydrous geofluids from depths of around 3.5 to 5 km and temperatures of 450-600°C. At that depth, the pressure and temperature of pure water exceed the critical point of 374.15°C and 221.2 bars, which means that only a single phase fluid exists. In order to drill into the target zone of supercritical geofluids, one of the main challenges is to deal with high temperatures and pressures during the drilling and well completion processes. Because of the great uncertainties in this project a detailed risk assessment and contingency plan is necessary.
This thesis describes major geological and technical problems, in terms of drilling, in such a high temperature and pressure environment, with emphasis on the geo-engineering part of the drilling process and well completion. The natural geological risks arising from volcanic and seismic activity, as well as meeting sufficient permeable zones, are considered to be relatively minor factors when compared to the well completion process due to their low probability. The main risks are assessed in the hazard of underground pressure blowouts, meeting circulation loss zones and material failures due to the high temperature environment. In addition borehole failure, formation fracturing, cement and casing failure as well as problems during coring operations are deemed to be likely, but by applying the appropriate techniques as well as mitigation and counteractive measures, discussed in this thesis, most of these risks can be reduced or prevented.
Modeling of IGFC System [PDF]
CO2 removal from gas streams, using membrane reactors
© Raido Huberg, 2009 (Fuel Cell Systems & Hydrogen)
Abstract
In the following work, the different capture concepts of carbon dioxide from an IGFC power plant have been considered and analyzed. The main objective was to compare the net power output according to the different tail-gas processing concepts (oxy-combustion, H2- and O2-conducting membranes) and to compare the difference of output when CO2 is vented.
The first concept considered is an IGFC plant (integrated gasification gas combined cycle plant with a fuel cell) with oxy-combustion for oxidizing the remaining fuel in the anode tail-gas. The second and third concepts are H2-conducting membranes, one with N2 and the other with air as sweep gas. The fourth concept involves an O2-conducting membrane in which O2 permeates from the cathode side to the anode side without mixing the two streams with each other. Also a fifth concept was developed, where the anode and cathode flows are mixed and no CO2 capture takes place. In the presented dissertation, a model with zero- and one-dimensional (membrane model) computational parts was created to simulate and evaluate the capability of the IGFC plant using different means to capture carbon dioxide.
The efficiency and net power of the different tail-gas concepts were compared, assuming an IGFC plant with oxy-combustion for carbon dioxide capture as the baseline. The capture of carbon dioxide proved to have an efficiency and probably an investment cost penalty. A Carbon Tax (adopted in some countries like Sweden) proportional to the number of kilograms of carbon dioxide released in the environment is necessary to make the carbon dioxide capture economically feasible.
Þeistareykir high-temperature geothermal field, North-East Iceland [PDF]
Estimation of reservoir conditions and evaluation of pressure interference between wells
© Júlía Úlfdís Jóhannsson (Geothermal Energy Specialization)
Abstract
The Þeistareykir high-temperature geothermal field is located in northern Iceland. Seven deep boreholes have been drilled there since 2002. Temperature and pressure logs, measured during different operational stages of the wells, were analyzed to estimate formation temperature and initial pressure, as well as the possible location of feed zones in the wells. A new interpretation supports the hypothesis of an up-flow around well ÞG-1. It is possible that the up-flow does not spread as far to the west as was previously assumed.
The highest temperatures measured in the new wells ÞG-5B and ÞG-6 were 300°C and 311°C, respectively. The discharge enthalpy for well ÞG-5B is higher than it is for well ÞG-5. Discharge from well ÞG-6 will possibly have similar characteristics as the discharge from wells ÞG-1 and ÞG-3, i.e. high temperature steam. Pressure recovery measurements in wells, which were shut in during the summer of 2008, have been evaluated using conventional well test analysis methods. The results obtained were compared with results of the interpretation of step-rate injection test data. Transmissivities evaluated in this work for wells ÞG-1 and ÞG-3 are lower than previous estimates while skin factor estimates have become more negative.
Transmissivity, estimated by the analysis of injection test data for well ÞG-5B is close to the transmissivity estimated for well ÞG-5, or in the order of 7x10-8 m3/Pa-s; transmissivity, estimated for well ÞG-6 is close to the transmissivity for well ÞG-3, and in the order of 1.3 x10-8 m3/Pa-s. There are indications of interference between well ÞG-2 and wells ÞG-3, ÞG-5, ÞG-5B, and ÞG-6, as well as between ÞG-3 and ÞG-5. Well ÞG-1 has a limited communication with wells ÞG-2 and ÞG-3, however.
3D Modeling of a Geothermal Reservoir in the Central Part of Kosice Basin in the Eastern Slovakia [PDF]
© Katarína Kamenská (Geothermal Energy Specialization)
Abstract
The question of energy needed for enhancing human comfort has recently become very popular and geothermal energy, as one of the most promising renewable energy sources, has started to be utilized not only for recreation purposes, but also for heating and probably electricity generation in Slovakia. Slovakia is a country which has proper geological conditions for geothermal source occurrence. Kosice Basin seems to be the most prospective geothermal area – the reservoir rocks are Middle Triassic dolomites with fissure karstic permeability and basal Karpathian clastic rocks at the depth of 2100 – 2600 m, with an average temperature around 135 °C. Seismic data from the central part of Kosice basin enabled the demonstration of position, spatial distribution, morphology and tectonic structure of reservoir rocks and their Neogene overlier as an insulator. Based on a 3D tectonic model, reservoir rocks are segmented into individual blocks which probably do not communicate with surrounding blocks in terms of geothermal water flow. Tectonic and geologic aspects affect the thickness of sedimentary sequences, which is demonstrated by variable thickness in the whole space of the modeled area. The model showed at least one potential geothermal area, but for further evaluation detailed geophysical measurements are needed. Geothermal sources in central Kosice Basin as a home source can reduce dependence on gas and other fossil fuels. Utilization of geothermal sources can secure energy supply for Kosice town and prevent future shortages in energy as happened in January 2008 when Russia cut gas supply to part of Europe, including Slovakia. Geothermal utilization produces much less greenhouse gasses as conventional fossil fuel plants and in the case of reinjection there is no emission to the atmosphere. Probably the biggest disadvantage of geothermal utilization in the area of interest is high capital cost.
Feasibility study of binary geothermal power plants in Eastern Slovakia [PDF]
Analysis of ORC and Kalina power plants
© Martina Kopuničová (Geothermal Energy Specialization)
Abstract
Slovakia is among the countries of the European Union which signed the regulation related to renewable energy source utilization.
According to European Union statistics from 2005, Slovakia is number 22 in terms of renewable energy usage, with 6.7% of its energy from renewable sources. The regulation states that by the year 2020, Slovakia must increase its usage to 14%, which means doubling the renewable fraction of total energy consumption. Slovakia is one of the countries in central Europe with high geothermal resources occurrence which are not used sufficiently. The disadvantage of these sources is a low temperature. These low temperature sources can be used directly for district heating or to produce electrical power.
For low temperature source utilization the most applicable power generation is using small binary power plants - Organic Rankine Cycle (ORC) or Kalina cycle. The aim of this work is to model the ORC and Kalina cycle using data obtained from East Slovakian sources and to compare these two systems in terms of efficiency, power output, usability in Slovakian conditions and financial feasability. The largest source in Eastern Slovakia is located in a placed near Kosice city – Durkov. (Giese, 1998)
Results of the modeled thermodynamical comparison show that the Kalina cycle is more feasible in Durkov area conditions. Looking at the basic investments analysis the decision of which modeled power plant is better is a complicated one to make.
Effectiveness of Financial Support in European Union Countries in Terms of Bioenergy [PDF]
Differences between Germany, Poland and Spain
© Magda Kozak (Biofuels & Bioenergy Specialization)
Abstract
In light of increasing energy insecurity, in which countries try to obtain their own, independent resources, the need for yearly financial support is increasing. Countries continue to search for new renewable energy possibilities and successfully implement new, not yet well-known technologies. However, these expensive technologies will never be able to succeed without support since the market for current renewable energy and feedstock prices are still not competitive with the fossil fuel market.
The aim of this project is to show the possibilities of financial vehicles, which are still in the development phase, for European countries. Special attention is given to the bioenergy sector, which is considered to have the highest potential to replace primary energy sources. The study is based on the examples of three countries: Germany, as a leader of renewable energy development not only in Europe but also throughout the world; Spain, which in recent years significantly increased its share of renewable resources in final energy consumption; and Poland, as a country in transition with high bioenergy potential.
The study shows the variety of financial possibilities, in form of supports or funds, that have recently emerged. However, the problem lies with individual government implementation effectiveness. All considered countries showed an increase in installed bioenergy capacities, mainly because of benefits provided through financial supports. Unfortunately, in most cases the results are not sufficient.
The problem is that a lack of consistent data concerning subsidies for different fuels across EU 27 was an obstacle in reaching more defined conclusions. However, the analysis of the chosen countries concluded that feed-in tariffs are far ahead in terms of effectiveness and influence on technological development as compared to quota obligations.
Future studies of this topic will most likely implement new solutions which will lead to a more clear understanding of the procedures and will mainly focus on Member States policy papers and legislations.
Implementation problems with European Union’s energy system regulations in Central East Europe [PDF]
© Jan Krawczyk (Biofuels & Bioenergy Specialization)
The 1992 Earth Summit in Rio de Janeiro spearheaded concerns about the environment and the future wellbeing of Earth and human civilization. It highlighted the importance of green energy and sustainable energy development. The European Union’s Council progressed forward, spring boarding off of the environmental concerns and scientific knowledge, to establish and develop regulations, laws and tools to promote green and sustainable energy in Europe.
This analysis will focus on the regulations, laws, and directives of the European Union’s primary energy market. It describes the background of the main European Council’s (EC) energy sector regulation documents and analyzes the following: Directive 2006/32/EC on energy end-use efficiency and energy services, Directive 2001/77/EC on the promotion of electricity produced from renewable energy sources in the internal electricity market and Directive 2003/30/EC on the promotion of the use of biofuels or other renewable fuels for transport. This work provides a general overview, highlights the main goals, and reports on the mechanisms, both proposed and in effect, used to reach these established goals. Lastly, this thesis will investigate the penalty system, or lack thereof, and discuss the difficulties in measuring its results.
The implementation of these directives is discussed for a representative sample of three Central Eastern Europe countries, specifically the Slovak Republic, the Czech Republic, and Poland. New European Union Member States have different markets, economical situations, energy sources, and supplies. This work will analyze the energy sector in terms of renewable energy, energy efficiency, and biofuels market. It shows the targets for each country and the forecasts concerning energy production. Finally, an overview of the energy policies needed to reach the goals will be presented, along with conclusions as to whether it will be possible or not to achieve the Directives’ levels.
As a result of this work it is noted that the Slovak Republic and the Czech Republic, both with very young but solid renewable energy policies, have and will have huge problems with achieving their set goals. The main problem in these countries is the lack of investors, capital, and experience within the renewable energy sector. In Poland however, despite the appearance of ineffective green energy policy compared to other countries, production of electricity from renewable energy sources and energy efficiency policies have taken effect.
This thesis considers the implementation of EC’s directives by analyzing the energy systems, energy policy, and goals set by these countries. It will show the difficulties in reaching the objectives set by the European Council’s directives and inaccuracies in the implementation of these tools.
Feasibility study of CHiP plants in the European Union using pure plant oils [PDF]
© Michal Krzyzaniak (Biofuels & Bioenergy Specialization)
Abstract
The purpose of this work is to investigate in which EU member States it is possible to utilize Combined Heat and Intelligent Power technology, which can produce electricity with high efficiency. The paper investigates the Member States’ policies and subsidies for renewable electricity production from liquid biomass and additional tax deduction and benefits. The result shows that four Member States are the most promising: Germany, Austria, Portugal and The Netherlands. Research for the sustainability of pure plant oils is also part of this work. The investigation shows that the most common in use plant oils such as palm, rapeseed, jatropha, soybean can contribute to the greenhouse gases reduction. However, incorrect land use and irresponsible deforestation can increase GHG emission more than 20 times. Thus, Blue-NG company must be ready to surmount high opposition for the use of plant oils from developing countries.
Considerations regarding modeling of MW-scale IG-SOFC Hybrid Power System [PDF]
© Jakub Kupecki (Fuel Cell Systems & Hydrogen Specialization)
Abstract
The main objective of this thesis is to evaluate various modeling approaches for large systems employing high temperature fuel cell (particularly SOFC) modeling. It also includes a brief discussion of current trends and various designs. This thesis will review recently published papers investigating the hundred MWe scale SOFC hybrid Brayton-Rankine power systems. It goes into details discussing the crucial parameters influencing the cycle’s operation and performance. For better understanding, the basics of the fuel cell operation, involved processes and all phenonena are provided in Chapter 2.
In the next chapter the SOFC based systems with integrated gasification reactors are widely described. Current state-of-the-art trends and their background are presented. Finaly the desired system configuration is proposed and investigated. These particular arragements correspond to the U.S. Department of Energy (DoE) baseline for systems employing high temperature fuel cells, hence certain design solutions are involved. The SOFC stack feedstock is provided by the gasification of coal, however different fuel can also be gasified (biomass for example).
In the last chapter, the modeling and optimisation in the software are extensively described. Because of the fact that ASPEN Plus and Hysys are comonly used in the majority of cases when cycles involing high temperature fuel cells are analyzed, the attention will be focused on these two programs. Both of them have built-in tools allowing the modeling of heat exchangers, compressors and expanders (i.e. gas and steam turbines) by available units. ASPEN Plus is Fortran based software and the SOFC stack can be modeled as a user unit using this programming code. The modeling approach to the electrochemical and chemical processes within the SOFC stack will be delivered, since it is important for the modeling of the entire power cycle. Analysis of the whole system with the proposed tools allows the determination of the overall system thermal efficiency with high fidelity, thus the biggest effort must be made to correctly determine all input parameters and define the proper assumptions as well as simplifications. The final discussion emphasises the most crucial parameters.
The proposed system represents a clean energy source, which substantialy reduces the polutants flow associated with the power generation. Desulphurisation and gases clean-up processes are also involved in the cycle, therefore it meets all environmental requirements.
A New Geothermal Cooling – Heating System for Buildings [PDF]
Geothermal Cooling – Heating for Hot – Humid Climates
© Pawel Jan Lech (Geothermal Energy Specialization)
Abstract
Single stage absorption chillers (water/lithium bromide) can operate using low grade heat, thus single stage absorption chillers can operate using low temperature geothermal resources. An EES computer model was written for a single stage absorption chiller based on overall heat transfer coefficients, mass flows, salt balances, energy balances and other assumptions. The single stage model was calibrated with well known and available data from US and Japanese manufacturers. The system was considered to work in hot and humid climates like those in Abu Dhabi and Shanghai. The results show that when cooling water is 28 °C hot the initial and annual total cost is high. However, as cooling water temperature decreases, the initial and annual total cost decreases sharply (when cooling water is at 20°C the reduction is around 35% of the total annual cost). The results show a great influence of cold and hot water on the performance and total annual cost of absorption chillers.
The second part of the computer model contains a Total Equivalent Warming Impact (TEWI) analysis. TEWI considers both the direct refrigerant effects and the primary energy impact on equivalent carbon dioxide (CO2) emissions. Competing technologies are vapour–compression and gas cycles. The results show some recommendations for absorption system diversification to reduce the Total Equivalent Warming Impact. The results also show that absorption hot water chillers have the lowest contribution to Global Warming (TEWI).
Retrograde Alteration of Basaltic Rocks in the Þeistareykir High-Temperature Geothermal Field, North-Iceland [PDF]
© Krisztina Marosvölgyi (Geothermal Energy Specialization)
Abstract
Hydrothermal alteration of basaltic rocks in a drill core from well ÞR-7 in the geothermal area on Þeistareykir was studied by microscope and X-ray powder diffraction (XRD) methods. Emphasis was laid on the study of clay minerals (sheet silicates) and zeolites formed by hydrothermal alteration. The reservoir rocks in the area are medium to highly hydrothermally altered. The rock forming minerals have been transformed to clay minerals or sheet silicates and several secondary minerals have been precipitated in vugs and factures. Several different clay mineral types were identified in the altered rocks: smectite, chlorite, mixed-layer minerals of of chlorite/smectite, mostly irregular types and irregular chloritic mixed-layer sheet silicates. Smectie/illite mixed-layer minerals were also encountered. The XRD diffraction patterns of the clay mineral samples from well ÞR-7, are quite complex and not easy to interpret, as the minerals are often poorly crystalline and not pure components of any single type of minerals. A regular clay zonation from smectite through mixed layer smectite-chlorite to chlorite, as is common in high-temperature geothermal fields in Iceland, is not observed in the ÞR-7 core. The zeolite types identified in the core are laumontite, yugawaralite, mordenite and wairakite. The zeolite yugawairalite is quite rare and previously only encountered in three localities in Iceland. The higher temperature zeolite wairakite is found in the middle of a zone dominated by the lower temperature zeolite laumontite. Therefore dispersion of the secondary minerals does not show a very clear zonation of the alteration minerals, and correlation to rock temperature is not easily obtained. Some of the clay minerals/sheet silicates encountered suggest a retrograde alteration of previously formed clay minerals at lower temperatures than the original hydrothermal alteration. The occurrence of zeolites in the core implies a similarity to the higher temperature zeolite wairakite that occurs in a laumontite dominant zone. The rock temperature in well ÞR-7 appears to have been higher at earlier times than at present, showing an overprint of lower temperature secondary minerals.
Design and Optimization of Standardized Organic Rankine Cycle Power Plant for European Conditions [PDF]
© Maciej Lukawski (Geothermal Energy Specialization)
Abstract
This paper investigates the possibility of introducing universally designed binary power plants into European energy markets. ORC cycles are found to be particularly useful not only for the production of electricity from geothermal water, but also for the recovery of waste heat from engine exhaust gasses, furnaces and drying ovens. In this dissertation, an analysis of market demand and thermodynamic characteristics of different heat sources is performed in order to find an optimal set of design boundary conditions maximizing unit performance for the most promising types of applications.
A thermodynamic model of a power plant using a wet mechanical-draft cooling tower is created in EES software and a detailed analysis of component configuration and parameters of working fluids is carried out.
Optimal plant configuration and size of components is found by thermoeconomic optimization. Exergy flow rates of all streams in the system as well as rates of exergy destruction and loss are quantified. Detailed economic analysis of the unit is made for four different applications: geothermal plants using water from conventional hydrothermal wells, former oil and gas boreholes, waste heat recovery plants coupled with diesel engines, and a clinker cooler in a cement plant.
Finally, a sensitivity analysis shows the impact that changes in heat source characteristics and macroeconomic variables have on levelized cost of power.
Solid Oxide Fuel Cell System Control [PDF]
Modeling and Control Study of a Catalytic Partial Oxidation (CPOX) Reactor
© Tomasz Szczęsny Miklis (Fuel Cell Systems & Hydrogen Specialization)
Abstract
An advanced thermodynamic model of a catalytic partial oxidation (CPOX) reactor was developed. The dynamics of the reactor were simulated using differential algebraic equations (DAEs). The aim of the project was to create a reliable and fast model that will be used, for control purposes, to maximize the hydrogen yield from the CPOX reaction. The composition of the output flow and species concentration is controlled by the input mass flows of fuel (Dodecane) and air. The state variables of the reactor considered in this model are temperature and total internal energy of the reactor. There are many options with which to customize the reactor model, from the geometry and materials used to build the reactor shell to different compositions of the gases fed to the reactor (fuel and air). The Cantera toolbox was used to simulate chemistry and the whole project was completed the in MATLAB programming environment.
Bioprocess Design: The GEOGAS Project [PDF]
Bioremediation of geothermal gases and SCP production with HOX/SOX bacteria
© Michał Monit (Biofuels & Bioenergy Specialization)
Abstract
Bioprocess engineering is a field of science which lately has been experiencing huge growth. Progress in genetic engineering and microbiology, as well as engineering improvements, allow to overcome the limits, both technical and economical, experienced by industrial processes as recently as ten years ago. Still, bioprocess design and scale-up are highly interdisciplinary fields which rely heavily on previous work in the area. However, for novel processes, there is not much relevant research, which makes the introduction of new bioprocesses challenging. One such case is the GEOGAS project, which aims at utilization of sulfur- (SOX) and hydrogen-oxidizing (HOX) bacteria for simultaneous abatement of hydrogen sulfide and carbon dioxide from geothermal power plants and production of single-cell proteins (SCP). In this work bioprocess design (and engineering) principles are introduced to provide a GEOGAS-oriented framework for tackling new process introduction and scale-up. Further on, in the case study of the Project, the focus is placed on determining crucial factors and issues which could possibly be encountered during scale-up. The obtained results show that the current shape of the design is not yet satisfactory; however, it presents a possibly big gap for tackling numerous pollution and waste disposal problems. Finally, a brief discussion on possible project follow-up and development is presented.
Akureyri’s District Heating System: An Optimization Study [PDF]
Optimization of supply temperature
© Michał Pachocki (Geothermal Energy Specialization)
Abstract
Iceland is in first place in the world for direct use of geothermal energy per capita. The largest use of low temperature geothermal energy is for space heating in large districts of towns. The water sent to consumers in Akureyri town in north Iceland is a mix of hot geothermal water and water returning from users’ radiators. The goal of this work is to optimize the supply temperature to the district heating distribution network, in order to minimize the amount of water extracted from geothermal fields.
First the district heating system in Akureyri is described. Information on utilized geothermal fields, distribution system and equipment such as pumps, storage tanks, pipelines, etc. is presented. It is explained how the system is controlled.
The second part is a case study. Operational optimization of Naustahverfi’s district heating system is performed. A running curve for supply water temperature at the pumping station is designed and a mathematical model for this optimization is used. The choice is a macroscopic model that lumps the system into one equivalent user. Data on the supply water temperature and flow as well as outdoor temperature, provided by Norðurorka Company, is used for the simulation. A curve representing the lowest geothermal water consumption is found. The work reveals and addresses the limitations of a macroscopic model. It shows how the problem can be solved in case of unsuitability of part of the data and points out the need to modify the existing theory to include snow melting installations.
Well Design & Well Completion under Acidic Conditions [PDF]
Mitigation of corrosion of the wells of Krafla
© Gabor Rajnai (Geothermal Energy Specialization)
Abstract
Acidic wells are reported from several high temperature geothermal fields around the world, including the Geysers, Larderello, Miravalles, Los Humeros, Tatun, Taiwan, Saint Lucia, Windward Islands, and the Krafla. General corrosion rates can significantly influence the production, and in the case of well failures can lead to catastrophic consequences. The designer of the well has to choose whether to use expensive but corrosion resistant materials during the well completion, sacrifice the casing and the production liner and choose a cheaper grade steel or try to solve the corrosion problem by chemically treating the well. This work will try to determine the best potential corrosion resistant materials that can be applied during the completion of a geothermal well, review state of the art information about scaling inhibition due to increased iron concentration and calculate the potential dose rate of caustic injection in the case of well KJ-36.
Renewable heat and electricity supply to residential settlements [PDF]
Gas versus heat transport for low-energy housing
© Tomasz Sasin (Fuel Cell System & Hydrogen Specializtion)
Abstract
The use of energy in the residential sector is among the most significant causes of global warming and greenhouse gas emissions. The majority of energy consumed in households accounts for space heating and the preparation of warm water. The key to decreasing energy consumption is increasing energy efficiency. The most progress in energy efficiency in the residential sector is expected to be made by improving the insulation of buildings and using low-energy equipment. However, in settlements with very high insulation standards, transport of heat becomes senseless as heat losses may be higher than delivered energy. The easiest way to eliminate losses in this case is generating heat directly at the consumer’s location. In the thesis seven ideas are proposed which eliminate heat transport and involve a switch to gas transport or direct electrical energy delivery. In the presented scenarios, all the energy delivered to the settlement comes from renewable energy sources. Four of the concepts were taken into further consideration and an energy efficiency analysis was performed for them. The thesis also presents an up-to-date overview of concepts regarding district heating, efficiency standards for buildings and statistics of renewable energy resources in Germany and the European Union.
The main conclusion reached from this research is that energy distribution by electricity and gases is more efficient than heat distribution and with the use of distributed generation it is possible to completely avoid losses that are present in heat delivery. The biggest problem concerning switching to renewable energy sources is storage of energy during periods of lack of energy delivery from primary sources. In terms of energy efficiency and environmental impacts, the use of biogas reformed in solid oxide fuel cells seems to have the least environmental footprint.
Setup of a test bench and testing the single solid oxide fuel cell at various temperatures [PDF]
© Marek Skrzypkiewicz (Fuel Cell Systems & Hydrogen Specialization)
Abstract
Solid Oxide Fuel Cells (SOFCs) are a promising source of electricity. They are efficient devices that allow direct harnessing the Gibbs free energy of reactions between fuel and an oxidant. The ongoing project in the Fuel Cell laboratory in Perugia, Italy is a part of their coordination with the Energy Research Center of Netherlands (ECN). This project was devoted to single SOFCs testing, which helps in understanding the influence of different circumstances on the SOFC performance. In this thesis is a detailed outline of the testing procedures and an expanded discussion of the results. The main objectives of this work were to: finish building the single SOFC test bench, create a model that allowed time and gas consumption forecasting for different tests, design the sulphur tolerance system, create a model for cell temperature evaluation, study recent scientific achievements in SOFC with special emphasis on single cells testing, prepare the laboratory testing procedures, perform the tests of the ASC2 Cell by InDEC B.V. The results are presented in graphs in the body of the work and in detailed tables as an appendix. The measurements gave results worse than expected, but the temperature dependence is clear. The conclusions for future development of the test bench are that the temperature measuring should be improved and software development should continue.
A wind-power fuel cell hybrid system study [PDF]
Model of energy conversion for wind energy system with hydrogen storage
© Katarzyna Sobotka (Fuel Cell Systems & Hydrogen Specialization)
Abstract
Hydrogen, as a form of long term storage for the excess energy from renewable sources, is a technically and economically viable option. However, the technology is not mature enough to compete with the other renewable energy possibilities. In this thesis, a study based on coupling a wind-turbine with a fuel cell to improve the utilization of wind power is presented.
A part of the energy produced by the wind-turbine is stored in the form of hydrogen and is then delivered for consumption at variable power through a fuel cell. A model was developed to determine the key technical parameters influencing the operation of a wind energy system with hydrogen storage. The model incorporates the simulation results of a 600 kW wind energy system with a 100 kW Proton Exchange Membrane Fuel Cell (PEMFC) and an electrolyzer. Dynamic modeling of various components of this small isolated system is presented for the period from 1.1.2006 to 31.1.2006. In this way, the energy availability can be estimated and is presented for hybrid installations. The study presents the technology of the system for each particular element.
This study is a general introduction for the wind energy system with hydrogen storage. Future studies should be more complex and detailed in order to understand and model the system with greater accuracy and to increase the possibility for the utilization of wind energy to generate hydrogen. This would enhance wind power competitiveness and sustain the continuously changing world energy demand.
Design of a water-CO2 evaporator [PDF]
Corrosion in the Kalina cycle [PDF]
An investigation into corrosion problems at the Kalina cycle geothermal power plant in Húsavík, Iceland
© Peter Whittaker (Geothermal Energy Specialization)
Abstract
An overview of the utilization of geothermal energy in Húsavík Iceland is given. Corrosion is discussed in a theoretical manner, with references to the literature for examples of different mechanisms of corrosion. Samples taken from the Húsavík power plant were analyzed by SEM and X-ray EDS, the theory behind this method is discussed and the results are given. Ultimately the investigation into why there were corrosion problems was inconclusive but instructive. Hypotheses discussed in the conclusion, with ways to further investigate them, include: dissolution of micro-constituents in the ammonia environment, galvanic corrosion, stray current corrosion and erosion corrosion. Mild steel and aluminum seem to be inappropriate materials for Kalina cycle systems but several stainless steels (304, 316, nitronic 60 and duplex) as well as 6Al-4V titanium do not appear to suffer from corrosion.
Slow pyrolysis in a rotary kiln reactor: Optimization and experiment [PDF]
© Luka Zajec (Biofuels & Bioenergy Specialization)
Abstract
Biomass is the fourth largest source of energy worldwide after coal, oil and natural gas. Among the various technologies encompassing biomass energy conversion, some may be considered to have
reached a level of technological development which allows use on an industrial scale while others require further testing to increase yields and reduce costs of energy conversion and management. The
thermochemic conversion of biomass (pyrolysis, gasification, combustion) represents the most promising technique for energy production.
In this context fits the application of the process of slow pyrolysis of biomass in a rotary kiln reactor with an integrated gas burner of small size for a continuous production of syngas. The objectives of this work are: To run a micropyrolyser in a rotary kiln reactor which was out of use for several years; To connect the micropyrolyser with a gas burner for determination of produced and exhaust gases; To run the pyrolyser in a continuous way for continuous production of syngas; To determine biomass mass flow and mass and energy balance of the system; To perform Proximate and Ultimate analyses of initial biomass and produced char and tar with a gas chromatographer to determine LHV of syngas.
Two tests were performed during the course of this thesis work: A drying test of biomass and a pyrolysis test with a direct combustion of the produced syngas inside a gas burner. An analyzed sample of a gas mixture indicated a lower calorific value of 2,86 MJ/kg of the syngas due to the intake of a considerable amount of ambient air and unintentional leaks and loose-fitting seals. Theoretically, if an anaerobic environment could be achieved inside the micropyrolyser, the produced syngas would have the calorific value of 12,79 MJ/kg, a figure that can also be found in literature. To increase the calorific value of continuously produced gas in a micropyrolyser, the sealing system should be improved.
The work was conducted on a micropyrolyzer located in a pilot plant at the Department of Industrial Engineering, Faculty of Engineering at the University of Perugia, Italy.
The reports are not to be duplicated or printed without written consent by the author and RES.
Formation of Lanthanum Zirconates in Solid Oxide Electrolysis Cells [PDF]
Experimental Studies
© Pedro Miguel da Costa Almeida (Fuel Cell Systems & Hydrogen Specialization)
Abstract
Versa Power Systems solid oxide cells were tested with the objective of performing long term electrolysis testing and studying their degradation and, more specifically, the creation of insulating phases of lanthanum zirconates. Three cells were tested but only one sustained long term electrolysis testing. The other two fractured due to excessive fuel flow and lack of heating in inlet tubes. A different sealing method and bubbler were used in the third tested cell. This cell showed good initial performance with power densities around 0.32 W/cm2 and with an ASR of 0.59 Ω.cm2 running on 175sccm H2 / 175sccm H20. The cell ran in electrolysis mode for 290 hours showing a steady degradation that eventually stabilized and even recovered in the last tens of hours. These are thought to be passivation and activation processes due to the silica based sealant (Hauch A. E., 2008). Scanning electron microscopy (SEM) and x-ray diffraction (XRD) measurements were performed after cell testing. They showed no significant microstructural changes and no presence of the insulating phase. A previous report on another VPS cell showed the possibility of the presence of this phase in an XRD test. Yet when a second XRD test was done these phases were not found. This might be explained if we consider that these phases form under the places where platinum paste is present, which conforms to the two different microstructural areas found in the SEM images in the previous tested cell.
Experimental Studies
© Pedro Miguel da Costa Almeida (Fuel Cell Systems & Hydrogen Specialization)
Abstract
Versa Power Systems solid oxide cells were tested with the objective of performing long term electrolysis testing and studying their degradation and, more specifically, the creation of insulating phases of lanthanum zirconates. Three cells were tested but only one sustained long term electrolysis testing. The other two fractured due to excessive fuel flow and lack of heating in inlet tubes. A different sealing method and bubbler were used in the third tested cell. This cell showed good initial performance with power densities around 0.32 W/cm2 and with an ASR of 0.59 Ω.cm2 running on 175sccm H2 / 175sccm H20. The cell ran in electrolysis mode for 290 hours showing a steady degradation that eventually stabilized and even recovered in the last tens of hours. These are thought to be passivation and activation processes due to the silica based sealant (Hauch A. E., 2008). Scanning electron microscopy (SEM) and x-ray diffraction (XRD) measurements were performed after cell testing. They showed no significant microstructural changes and no presence of the insulating phase. A previous report on another VPS cell showed the possibility of the presence of this phase in an XRD test. Yet when a second XRD test was done these phases were not found. This might be explained if we consider that these phases form under the places where platinum paste is present, which conforms to the two different microstructural areas found in the SEM images in the previous tested cell.
Aluminum Alloy Drill Pipe in Geothermal Drilling [PDF]
Technical and Economical Opportunities
© Erin Rebecca Anderson (Geothermal Energy Specialization)
Abstract
The purpose of this investigation is to determine the application opportunities of aluminum alloy drill pipe (ADP) in geothermal drilling environments. The Geothermal Energy industry is at the tipping point of the global energy mix. Geothermal offers the benefits of other clean, sustainable energies such as low emissions but also boasts a small environmental footprint, base-load power, and widespread distribution as related to EGS applications. Additionally, with the improved development into ultra high energy extraction regions, the geothermal drilling industry is under high demand and is being tested to drill deeper, faster, and at reduced costs in order to make geothermal competitive economically and to satisfy energy demands. The achievement of greater drilling depths requires the advancement of the drilling industry to address limitations in the weight capacity of the drill rigs and the temperature limitations of the drilling components. Aluminum alloy drill pipes (ADP), sometimes referred to as Lightweight Aluminum Drill pipes (LADP) have been used in the drilling industry in Russia for many years. Due to ADP’s lightweight and high strength to weight ratio there are several advantages over conventional steel pipe. These advantages include the use of larger diameter drill pipe with thicker walls which increase annular flow; reduced pressure loss inside the drill pipe, resulting in smaller pump requirements; reduced derrick loads and hook loads due to reduced weight per length compared to steel and increased buoyancy effects in drilling fluids, resulting in smaller rigs or greater depth penetrations with current rigs; and reduced stresses in a number of drilling design parameters. The application ranges of ADP utilization will be studied in regards to temperature limitations, critical buckling loads and strength of materials, geothermal fluid chemistry, drilling fluid pressure losses and hydraulics, load comparisons, tool joint bonding, and economical cost analysis.
Exploration of Geothermal Systems with Petrel Modeling Software [PDF]
© Dorottya Bartucz (Geothermal Energy Specialization)
Abstract
In this thesis work an area located in Hungary was examined in order to localize the most promising site for geothermal water extraction for use in electricity production or in direct heat utilization systems.
Hungary is located in the central part of the Pannonian Basin. The geological evolution of the basin was favorable for the formation of low- and medium-enthalpy geothermal reservoirs throughout the country. These resources are already used in the balneology and agriculture sector. The utilization of the natural hot water in district heating systems and for domestic hot water supply has been developing fast in the recent years, while electricity generation from geothermal water is still in research phase.
A three-dimensional (3D) digital geological model of the area was created to support the localization of the best prospective site in the area of interest. For the model’s construction, eighteen two-dimensional (2D) seismic sections were used as input data. The Petrel geological modeling software, which was developed by Schlumberger Co, was used for data processing.
Three promising sites were designated in the studied area. Those sites were selected where the old deep and young shallower fractured zones cross each other by creating a locally extensional stress field. Due to the difficulties of the interpretation process the presence of the before mentioned requirements are very likely, but not certain, in the designated areas. Further exploration is crucial.
A comparison made between the computer supported analysis and the manual interpretation of hard copies of the seismic sections revealed that computer aided interpretation process lead to the recognition of more detailed tectonic structures in a relatively shorter time interval.
Hydrogen Fuel Cell Emergency Power System [PDF]
Installation and Performance of Plug Power GenCore 5B48 Unit
© Lech Birek & Stanisław Molitorys (Fuel Cell Systems & Hydrogen Specialization)
Abstract
Backup systems are crucial elements of modern electrical grids. They are used in places where an interruption in power supply can cause significant damage, e.g. in hospitals, banks or telecommunication towers. There are many solutions for how emergency power can be delivered. Hydrogen fuel cells are an emerging technology with great potential for the future. Fuel cells combine the advantages of batteries and diesel generators, and eliminate some of their significant disadvantages. They can work as long as they are supplied with fuel via a simple and efficient electrochemical reaction and at the same time they are quiet, produce no emissions and require minimum maintenance.
The aim of this thesis is to present the idea of hydrogen fuel cells as reliable backup power systems. The work consisted of two parts: one practical, the other theoretical. The first part includes the background of energy security, emergency power sources, fuel cell systems backup power market, as well as an introduction to fuel cell technology, principles of operation and hydrogen safety. The practical part of this project is focused on the Plug Power GenCore 5B48 fuel cell backup power unit, its description, installation, operation, safety precautions and performance characteristics.
The necessary hydrogen infrastructure was built according to safety codes and standards. The performance and reliability of the system was assessed. The system’s behavior was stable except for several minor problems during start-up which required intervention. The measured efficiency of the fuel cell stack and the whole system at the maximum available load of 1.65kW was 42.5% and 35.8% respectively. It was noted that the auxiliary load of the system has great influence on the overall performance of the system, especially at low output power. Noted fuel consumption was 13slm at 1kW and fuel utilization efficiency was estimated at around 99%. A cold start-up analysis was conducted and described based on the output data. During the first few minutes of operation the system required additional power to warm the fuel cell stack. The transition analysis focused on the ability of the system to provide power in case of a sudden outage. It was working well with batteries, as the fuel cell needed approximately 15 seconds to be ready to completely take over the power demand. Reliability and availability were assessed to be 96.8% and 79.9% respectively. It has to be pointed out that it was not possible to completely determine the system’s performance during some of the failure scenario and operation under different load because of the limitations of time and budget.
Biodiesel Production in Iceland [Restricted Access]
© Swietlana Borkowska (Biofuels & Bioenergy Specialization)
Abstract
The importance of increasing the global share of biofuels in transportation goes without saying. Iceland, where the consumption of fossil fuels is considerable, has a viable potential for introducing biodiesel in its otherwise exceptional renewable overall energy portfolio.
In this study, a full picture of the possibilities of biodiesel production in Iceland was provided. After the theoretical introduction of all major aspects of a biodiesel economy, an assessment of its applicability in Iceland was performed.
A survey of potential feedstocks was performed. It was concluded that in a short term perspective, a small scale production (300-2,000 tons/yr) can be carried out using domestically available waste raw material, and full scale production (15,000-80,000 tons/yr) will depend on imported feedstock.
After laboratory research, including waste vegetable oil (WVO), the main domestic feedstock currently available, the recommendation for the production process of a small production plant was made. It includes acid esterification of free fatty acids (FFA) followed by alkali transesterification and methanol recovery from the reacted mixture. At this stage, distillation of crude FAME was suggested, however further research is necessary.
The full scale production could substitute 8%-44% of the fossil diesel fuel needs for transportation and machinery. The estimated production costs in a full scale biodiesel plant, 0.63-0.76 EUR/L, are within the European average.
Fungi tar degradation [PDF]
Possible application for micro-scale slow pyrolysis rotary kiln
© Petra Božič (Biofuels & Bioenergy Specialization)
Abstract
When gas is cleaned in the process of slow pyrolysis in small-scale applications, water scrubbing is the most commonly used technology. After gas cleaning the tar and water vapors are trapped in the water, which is used for scrubbing. This waste water consists of condensed water vapors and two fractions of tar (water soluble and heavy tar). The product of this slow pyrolysis process is considered waste. None of the tar fractions are adequate for direct use in co-firing technologies. First it (water soluble tar fraction) contains too much water and later in the heavy tar there is not a sufficient quantity. The percentage of tar yielded from the slow pyrolysis process is not sufficient to be distilled in order to chemically clean components for further industry use, but that is the case in fast pyrolysis. That is why it is treated as chemical waste and needs to be disposed properly, which is a costly process. In order to reduce this cost a bioremediation method of fungi tar degradation has been examined. Fungi have a more potent enzyme system and are therefore far more appropriate for tar degradation than bacteria.
3D Modeling of Geothermal Reservoirs [PDF]
Case Study from Subtatric Basin in Western Carpathians, Slovakia
© Lucia Hlavácová (Geothermal Energy Specialization)
Geothermal energy is a potential renewable energy source that should be taken into account by the Slovak government. To aid geothermal exploration, 3D modeling is a very useful tool. The objective of this project was to model Poprad basin and the northern part of Hornad basin, in the Inner Carpathian system in Slovakia, to assess future prospective geothermal areas. These two are considered active geothermal areas. The main aquifers are built by Triassic carbonates – dolomites and limestones of Choc and Krizna nappe. In the central part of the Poprad basin, on the basis of seismic interpretation, Choc nappe thicknesses from 200 to 1100 m were obtained. Larger nappe thicknesses from 1200 to 1500 m were obtained on the east and southeast part of the studied area. The average value of the temperature gradient reaches 32.6 – 34.5° C/km and the average value of the heat flow density was estimated on 67mW/m2. Temperatures on the top of the Pre-Paleogene basement reach 50 – 85° C. In this work the geologic structure of the Gerlachov area, which is situated in the northwestern part of Poprad Basin, was also interpreted. From a geothermal point of view the formations with the most potential are Mesozoic units represented by Choc and Krizna Nappes underlying Paleogene rocks. Based on the geologic composition of Choc Nappe, the existence of very good conditions for a geothermal water reservoir can be expected. Krizna Nappe has less positive conditions for geothermal waters exploitation. General discharge of groundwater in Choc Nappe should be more than 22 l.s-1. The temperature in Choc Nappe is between 35 and 45° C.
Risk Management and Contingency Planning for Well IDDP-1 [PDF]
© Sebastian Homuth (Geothermal Energy Specialization)
Abstract
The Icelandic Deep Drilling Project (IDDP) is a research program designed to evaluate improvements in the efficiency and economics of geothermal energy systems by harnessing Deep Unconventional Geothermal Resources (DUGR). The goal is to generate electricity from natural supercritical hydrous geofluids from depths of around 3.5 to 5 km and temperatures of 450-600°C. At that depth, the pressure and temperature of pure water exceed the critical point of 374.15°C and 221.2 bars, which means that only a single phase fluid exists. In order to drill into the target zone of supercritical geofluids, one of the main challenges is to deal with high temperatures and pressures during the drilling and well completion processes. Because of the great uncertainties in this project a detailed risk assessment and contingency plan is necessary.
This thesis describes major geological and technical problems, in terms of drilling, in such a high temperature and pressure environment, with emphasis on the geo-engineering part of the drilling process and well completion. The natural geological risks arising from volcanic and seismic activity, as well as meeting sufficient permeable zones, are considered to be relatively minor factors when compared to the well completion process due to their low probability. The main risks are assessed in the hazard of underground pressure blowouts, meeting circulation loss zones and material failures due to the high temperature environment. In addition borehole failure, formation fracturing, cement and casing failure as well as problems during coring operations are deemed to be likely, but by applying the appropriate techniques as well as mitigation and counteractive measures, discussed in this thesis, most of these risks can be reduced or prevented.
Modeling of IGFC System [PDF]
CO2 removal from gas streams, using membrane reactors
© Raido Huberg, 2009 (Fuel Cell Systems & Hydrogen)
Abstract
In the following work, the different capture concepts of carbon dioxide from an IGFC power plant have been considered and analyzed. The main objective was to compare the net power output according to the different tail-gas processing concepts (oxy-combustion, H2- and O2-conducting membranes) and to compare the difference of output when CO2 is vented.
The first concept considered is an IGFC plant (integrated gasification gas combined cycle plant with a fuel cell) with oxy-combustion for oxidizing the remaining fuel in the anode tail-gas. The second and third concepts are H2-conducting membranes, one with N2 and the other with air as sweep gas. The fourth concept involves an O2-conducting membrane in which O2 permeates from the cathode side to the anode side without mixing the two streams with each other. Also a fifth concept was developed, where the anode and cathode flows are mixed and no CO2 capture takes place. In the presented dissertation, a model with zero- and one-dimensional (membrane model) computational parts was created to simulate and evaluate the capability of the IGFC plant using different means to capture carbon dioxide.
The efficiency and net power of the different tail-gas concepts were compared, assuming an IGFC plant with oxy-combustion for carbon dioxide capture as the baseline. The capture of carbon dioxide proved to have an efficiency and probably an investment cost penalty. A Carbon Tax (adopted in some countries like Sweden) proportional to the number of kilograms of carbon dioxide released in the environment is necessary to make the carbon dioxide capture economically feasible.
Þeistareykir high-temperature geothermal field, North-East Iceland [PDF]
Estimation of reservoir conditions and evaluation of pressure interference between wells
© Júlía Úlfdís Jóhannsson (Geothermal Energy Specialization)
Abstract
The Þeistareykir high-temperature geothermal field is located in northern Iceland. Seven deep boreholes have been drilled there since 2002. Temperature and pressure logs, measured during different operational stages of the wells, were analyzed to estimate formation temperature and initial pressure, as well as the possible location of feed zones in the wells. A new interpretation supports the hypothesis of an up-flow around well ÞG-1. It is possible that the up-flow does not spread as far to the west as was previously assumed.
The highest temperatures measured in the new wells ÞG-5B and ÞG-6 were 300°C and 311°C, respectively. The discharge enthalpy for well ÞG-5B is higher than it is for well ÞG-5. Discharge from well ÞG-6 will possibly have similar characteristics as the discharge from wells ÞG-1 and ÞG-3, i.e. high temperature steam. Pressure recovery measurements in wells, which were shut in during the summer of 2008, have been evaluated using conventional well test analysis methods. The results obtained were compared with results of the interpretation of step-rate injection test data. Transmissivities evaluated in this work for wells ÞG-1 and ÞG-3 are lower than previous estimates while skin factor estimates have become more negative.
Transmissivity, estimated by the analysis of injection test data for well ÞG-5B is close to the transmissivity estimated for well ÞG-5, or in the order of 7x10-8 m3/Pa-s; transmissivity, estimated for well ÞG-6 is close to the transmissivity for well ÞG-3, and in the order of 1.3 x10-8 m3/Pa-s. There are indications of interference between well ÞG-2 and wells ÞG-3, ÞG-5, ÞG-5B, and ÞG-6, as well as between ÞG-3 and ÞG-5. Well ÞG-1 has a limited communication with wells ÞG-2 and ÞG-3, however.
3D Modeling of a Geothermal Reservoir in the Central Part of Kosice Basin in the Eastern Slovakia [PDF]
© Katarína Kamenská (Geothermal Energy Specialization)
Abstract
The question of energy needed for enhancing human comfort has recently become very popular and geothermal energy, as one of the most promising renewable energy sources, has started to be utilized not only for recreation purposes, but also for heating and probably electricity generation in Slovakia. Slovakia is a country which has proper geological conditions for geothermal source occurrence. Kosice Basin seems to be the most prospective geothermal area – the reservoir rocks are Middle Triassic dolomites with fissure karstic permeability and basal Karpathian clastic rocks at the depth of 2100 – 2600 m, with an average temperature around 135 °C. Seismic data from the central part of Kosice basin enabled the demonstration of position, spatial distribution, morphology and tectonic structure of reservoir rocks and their Neogene overlier as an insulator. Based on a 3D tectonic model, reservoir rocks are segmented into individual blocks which probably do not communicate with surrounding blocks in terms of geothermal water flow. Tectonic and geologic aspects affect the thickness of sedimentary sequences, which is demonstrated by variable thickness in the whole space of the modeled area. The model showed at least one potential geothermal area, but for further evaluation detailed geophysical measurements are needed. Geothermal sources in central Kosice Basin as a home source can reduce dependence on gas and other fossil fuels. Utilization of geothermal sources can secure energy supply for Kosice town and prevent future shortages in energy as happened in January 2008 when Russia cut gas supply to part of Europe, including Slovakia. Geothermal utilization produces much less greenhouse gasses as conventional fossil fuel plants and in the case of reinjection there is no emission to the atmosphere. Probably the biggest disadvantage of geothermal utilization in the area of interest is high capital cost.
Feasibility study of binary geothermal power plants in Eastern Slovakia [PDF]
Analysis of ORC and Kalina power plants
© Martina Kopuničová (Geothermal Energy Specialization)
Abstract
Slovakia is among the countries of the European Union which signed the regulation related to renewable energy source utilization.
According to European Union statistics from 2005, Slovakia is number 22 in terms of renewable energy usage, with 6.7% of its energy from renewable sources. The regulation states that by the year 2020, Slovakia must increase its usage to 14%, which means doubling the renewable fraction of total energy consumption. Slovakia is one of the countries in central Europe with high geothermal resources occurrence which are not used sufficiently. The disadvantage of these sources is a low temperature. These low temperature sources can be used directly for district heating or to produce electrical power.
For low temperature source utilization the most applicable power generation is using small binary power plants - Organic Rankine Cycle (ORC) or Kalina cycle. The aim of this work is to model the ORC and Kalina cycle using data obtained from East Slovakian sources and to compare these two systems in terms of efficiency, power output, usability in Slovakian conditions and financial feasability. The largest source in Eastern Slovakia is located in a placed near Kosice city – Durkov. (Giese, 1998)
Results of the modeled thermodynamical comparison show that the Kalina cycle is more feasible in Durkov area conditions. Looking at the basic investments analysis the decision of which modeled power plant is better is a complicated one to make.
Effectiveness of Financial Support in European Union Countries in Terms of Bioenergy [PDF]
Differences between Germany, Poland and Spain
© Magda Kozak (Biofuels & Bioenergy Specialization)
Abstract
In light of increasing energy insecurity, in which countries try to obtain their own, independent resources, the need for yearly financial support is increasing. Countries continue to search for new renewable energy possibilities and successfully implement new, not yet well-known technologies. However, these expensive technologies will never be able to succeed without support since the market for current renewable energy and feedstock prices are still not competitive with the fossil fuel market.
The aim of this project is to show the possibilities of financial vehicles, which are still in the development phase, for European countries. Special attention is given to the bioenergy sector, which is considered to have the highest potential to replace primary energy sources. The study is based on the examples of three countries: Germany, as a leader of renewable energy development not only in Europe but also throughout the world; Spain, which in recent years significantly increased its share of renewable resources in final energy consumption; and Poland, as a country in transition with high bioenergy potential.
The study shows the variety of financial possibilities, in form of supports or funds, that have recently emerged. However, the problem lies with individual government implementation effectiveness. All considered countries showed an increase in installed bioenergy capacities, mainly because of benefits provided through financial supports. Unfortunately, in most cases the results are not sufficient.
The problem is that a lack of consistent data concerning subsidies for different fuels across EU 27 was an obstacle in reaching more defined conclusions. However, the analysis of the chosen countries concluded that feed-in tariffs are far ahead in terms of effectiveness and influence on technological development as compared to quota obligations.
Future studies of this topic will most likely implement new solutions which will lead to a more clear understanding of the procedures and will mainly focus on Member States policy papers and legislations.
Implementation problems with European Union’s energy system regulations in Central East Europe [PDF]
© Jan Krawczyk (Biofuels & Bioenergy Specialization)
The 1992 Earth Summit in Rio de Janeiro spearheaded concerns about the environment and the future wellbeing of Earth and human civilization. It highlighted the importance of green energy and sustainable energy development. The European Union’s Council progressed forward, spring boarding off of the environmental concerns and scientific knowledge, to establish and develop regulations, laws and tools to promote green and sustainable energy in Europe.
This analysis will focus on the regulations, laws, and directives of the European Union’s primary energy market. It describes the background of the main European Council’s (EC) energy sector regulation documents and analyzes the following: Directive 2006/32/EC on energy end-use efficiency and energy services, Directive 2001/77/EC on the promotion of electricity produced from renewable energy sources in the internal electricity market and Directive 2003/30/EC on the promotion of the use of biofuels or other renewable fuels for transport. This work provides a general overview, highlights the main goals, and reports on the mechanisms, both proposed and in effect, used to reach these established goals. Lastly, this thesis will investigate the penalty system, or lack thereof, and discuss the difficulties in measuring its results.
The implementation of these directives is discussed for a representative sample of three Central Eastern Europe countries, specifically the Slovak Republic, the Czech Republic, and Poland. New European Union Member States have different markets, economical situations, energy sources, and supplies. This work will analyze the energy sector in terms of renewable energy, energy efficiency, and biofuels market. It shows the targets for each country and the forecasts concerning energy production. Finally, an overview of the energy policies needed to reach the goals will be presented, along with conclusions as to whether it will be possible or not to achieve the Directives’ levels.
As a result of this work it is noted that the Slovak Republic and the Czech Republic, both with very young but solid renewable energy policies, have and will have huge problems with achieving their set goals. The main problem in these countries is the lack of investors, capital, and experience within the renewable energy sector. In Poland however, despite the appearance of ineffective green energy policy compared to other countries, production of electricity from renewable energy sources and energy efficiency policies have taken effect.
This thesis considers the implementation of EC’s directives by analyzing the energy systems, energy policy, and goals set by these countries. It will show the difficulties in reaching the objectives set by the European Council’s directives and inaccuracies in the implementation of these tools.
Feasibility study of CHiP plants in the European Union using pure plant oils [PDF]
© Michal Krzyzaniak (Biofuels & Bioenergy Specialization)
Abstract
The purpose of this work is to investigate in which EU member States it is possible to utilize Combined Heat and Intelligent Power technology, which can produce electricity with high efficiency. The paper investigates the Member States’ policies and subsidies for renewable electricity production from liquid biomass and additional tax deduction and benefits. The result shows that four Member States are the most promising: Germany, Austria, Portugal and The Netherlands. Research for the sustainability of pure plant oils is also part of this work. The investigation shows that the most common in use plant oils such as palm, rapeseed, jatropha, soybean can contribute to the greenhouse gases reduction. However, incorrect land use and irresponsible deforestation can increase GHG emission more than 20 times. Thus, Blue-NG company must be ready to surmount high opposition for the use of plant oils from developing countries.
Considerations regarding modeling of MW-scale IG-SOFC Hybrid Power System [PDF]
© Jakub Kupecki (Fuel Cell Systems & Hydrogen Specialization)
Abstract
The main objective of this thesis is to evaluate various modeling approaches for large systems employing high temperature fuel cell (particularly SOFC) modeling. It also includes a brief discussion of current trends and various designs. This thesis will review recently published papers investigating the hundred MWe scale SOFC hybrid Brayton-Rankine power systems. It goes into details discussing the crucial parameters influencing the cycle’s operation and performance. For better understanding, the basics of the fuel cell operation, involved processes and all phenonena are provided in Chapter 2.
In the next chapter the SOFC based systems with integrated gasification reactors are widely described. Current state-of-the-art trends and their background are presented. Finaly the desired system configuration is proposed and investigated. These particular arragements correspond to the U.S. Department of Energy (DoE) baseline for systems employing high temperature fuel cells, hence certain design solutions are involved. The SOFC stack feedstock is provided by the gasification of coal, however different fuel can also be gasified (biomass for example).
In the last chapter, the modeling and optimisation in the software are extensively described. Because of the fact that ASPEN Plus and Hysys are comonly used in the majority of cases when cycles involing high temperature fuel cells are analyzed, the attention will be focused on these two programs. Both of them have built-in tools allowing the modeling of heat exchangers, compressors and expanders (i.e. gas and steam turbines) by available units. ASPEN Plus is Fortran based software and the SOFC stack can be modeled as a user unit using this programming code. The modeling approach to the electrochemical and chemical processes within the SOFC stack will be delivered, since it is important for the modeling of the entire power cycle. Analysis of the whole system with the proposed tools allows the determination of the overall system thermal efficiency with high fidelity, thus the biggest effort must be made to correctly determine all input parameters and define the proper assumptions as well as simplifications. The final discussion emphasises the most crucial parameters.
The proposed system represents a clean energy source, which substantialy reduces the polutants flow associated with the power generation. Desulphurisation and gases clean-up processes are also involved in the cycle, therefore it meets all environmental requirements.
A New Geothermal Cooling – Heating System for Buildings [PDF]
Geothermal Cooling – Heating for Hot – Humid Climates
© Pawel Jan Lech (Geothermal Energy Specialization)
Abstract
Single stage absorption chillers (water/lithium bromide) can operate using low grade heat, thus single stage absorption chillers can operate using low temperature geothermal resources. An EES computer model was written for a single stage absorption chiller based on overall heat transfer coefficients, mass flows, salt balances, energy balances and other assumptions. The single stage model was calibrated with well known and available data from US and Japanese manufacturers. The system was considered to work in hot and humid climates like those in Abu Dhabi and Shanghai. The results show that when cooling water is 28 °C hot the initial and annual total cost is high. However, as cooling water temperature decreases, the initial and annual total cost decreases sharply (when cooling water is at 20°C the reduction is around 35% of the total annual cost). The results show a great influence of cold and hot water on the performance and total annual cost of absorption chillers.
The second part of the computer model contains a Total Equivalent Warming Impact (TEWI) analysis. TEWI considers both the direct refrigerant effects and the primary energy impact on equivalent carbon dioxide (CO2) emissions. Competing technologies are vapour–compression and gas cycles. The results show some recommendations for absorption system diversification to reduce the Total Equivalent Warming Impact. The results also show that absorption hot water chillers have the lowest contribution to Global Warming (TEWI).
Retrograde Alteration of Basaltic Rocks in the Þeistareykir High-Temperature Geothermal Field, North-Iceland [PDF]
© Krisztina Marosvölgyi (Geothermal Energy Specialization)
Abstract
Hydrothermal alteration of basaltic rocks in a drill core from well ÞR-7 in the geothermal area on Þeistareykir was studied by microscope and X-ray powder diffraction (XRD) methods. Emphasis was laid on the study of clay minerals (sheet silicates) and zeolites formed by hydrothermal alteration. The reservoir rocks in the area are medium to highly hydrothermally altered. The rock forming minerals have been transformed to clay minerals or sheet silicates and several secondary minerals have been precipitated in vugs and factures. Several different clay mineral types were identified in the altered rocks: smectite, chlorite, mixed-layer minerals of of chlorite/smectite, mostly irregular types and irregular chloritic mixed-layer sheet silicates. Smectie/illite mixed-layer minerals were also encountered. The XRD diffraction patterns of the clay mineral samples from well ÞR-7, are quite complex and not easy to interpret, as the minerals are often poorly crystalline and not pure components of any single type of minerals. A regular clay zonation from smectite through mixed layer smectite-chlorite to chlorite, as is common in high-temperature geothermal fields in Iceland, is not observed in the ÞR-7 core. The zeolite types identified in the core are laumontite, yugawaralite, mordenite and wairakite. The zeolite yugawairalite is quite rare and previously only encountered in three localities in Iceland. The higher temperature zeolite wairakite is found in the middle of a zone dominated by the lower temperature zeolite laumontite. Therefore dispersion of the secondary minerals does not show a very clear zonation of the alteration minerals, and correlation to rock temperature is not easily obtained. Some of the clay minerals/sheet silicates encountered suggest a retrograde alteration of previously formed clay minerals at lower temperatures than the original hydrothermal alteration. The occurrence of zeolites in the core implies a similarity to the higher temperature zeolite wairakite that occurs in a laumontite dominant zone. The rock temperature in well ÞR-7 appears to have been higher at earlier times than at present, showing an overprint of lower temperature secondary minerals.
Design and Optimization of Standardized Organic Rankine Cycle Power Plant for European Conditions [PDF]
© Maciej Lukawski (Geothermal Energy Specialization)
Abstract
This paper investigates the possibility of introducing universally designed binary power plants into European energy markets. ORC cycles are found to be particularly useful not only for the production of electricity from geothermal water, but also for the recovery of waste heat from engine exhaust gasses, furnaces and drying ovens. In this dissertation, an analysis of market demand and thermodynamic characteristics of different heat sources is performed in order to find an optimal set of design boundary conditions maximizing unit performance for the most promising types of applications.
A thermodynamic model of a power plant using a wet mechanical-draft cooling tower is created in EES software and a detailed analysis of component configuration and parameters of working fluids is carried out.
Optimal plant configuration and size of components is found by thermoeconomic optimization. Exergy flow rates of all streams in the system as well as rates of exergy destruction and loss are quantified. Detailed economic analysis of the unit is made for four different applications: geothermal plants using water from conventional hydrothermal wells, former oil and gas boreholes, waste heat recovery plants coupled with diesel engines, and a clinker cooler in a cement plant.
Finally, a sensitivity analysis shows the impact that changes in heat source characteristics and macroeconomic variables have on levelized cost of power.
Solid Oxide Fuel Cell System Control [PDF]
Modeling and Control Study of a Catalytic Partial Oxidation (CPOX) Reactor
© Tomasz Szczęsny Miklis (Fuel Cell Systems & Hydrogen Specialization)
Abstract
An advanced thermodynamic model of a catalytic partial oxidation (CPOX) reactor was developed. The dynamics of the reactor were simulated using differential algebraic equations (DAEs). The aim of the project was to create a reliable and fast model that will be used, for control purposes, to maximize the hydrogen yield from the CPOX reaction. The composition of the output flow and species concentration is controlled by the input mass flows of fuel (Dodecane) and air. The state variables of the reactor considered in this model are temperature and total internal energy of the reactor. There are many options with which to customize the reactor model, from the geometry and materials used to build the reactor shell to different compositions of the gases fed to the reactor (fuel and air). The Cantera toolbox was used to simulate chemistry and the whole project was completed the in MATLAB programming environment.
Bioprocess Design: The GEOGAS Project [PDF]
Bioremediation of geothermal gases and SCP production with HOX/SOX bacteria
© Michał Monit (Biofuels & Bioenergy Specialization)
Abstract
Bioprocess engineering is a field of science which lately has been experiencing huge growth. Progress in genetic engineering and microbiology, as well as engineering improvements, allow to overcome the limits, both technical and economical, experienced by industrial processes as recently as ten years ago. Still, bioprocess design and scale-up are highly interdisciplinary fields which rely heavily on previous work in the area. However, for novel processes, there is not much relevant research, which makes the introduction of new bioprocesses challenging. One such case is the GEOGAS project, which aims at utilization of sulfur- (SOX) and hydrogen-oxidizing (HOX) bacteria for simultaneous abatement of hydrogen sulfide and carbon dioxide from geothermal power plants and production of single-cell proteins (SCP). In this work bioprocess design (and engineering) principles are introduced to provide a GEOGAS-oriented framework for tackling new process introduction and scale-up. Further on, in the case study of the Project, the focus is placed on determining crucial factors and issues which could possibly be encountered during scale-up. The obtained results show that the current shape of the design is not yet satisfactory; however, it presents a possibly big gap for tackling numerous pollution and waste disposal problems. Finally, a brief discussion on possible project follow-up and development is presented.
Optimization of supply temperature
© Michał Pachocki (Geothermal Energy Specialization)
Abstract
Iceland is in first place in the world for direct use of geothermal energy per capita. The largest use of low temperature geothermal energy is for space heating in large districts of towns. The water sent to consumers in Akureyri town in north Iceland is a mix of hot geothermal water and water returning from users’ radiators. The goal of this work is to optimize the supply temperature to the district heating distribution network, in order to minimize the amount of water extracted from geothermal fields.
First the district heating system in Akureyri is described. Information on utilized geothermal fields, distribution system and equipment such as pumps, storage tanks, pipelines, etc. is presented. It is explained how the system is controlled.
The second part is a case study. Operational optimization of Naustahverfi’s district heating system is performed. A running curve for supply water temperature at the pumping station is designed and a mathematical model for this optimization is used. The choice is a macroscopic model that lumps the system into one equivalent user. Data on the supply water temperature and flow as well as outdoor temperature, provided by Norðurorka Company, is used for the simulation. A curve representing the lowest geothermal water consumption is found. The work reveals and addresses the limitations of a macroscopic model. It shows how the problem can be solved in case of unsuitability of part of the data and points out the need to modify the existing theory to include snow melting installations.
Mitigation of corrosion of the wells of Krafla
© Gabor Rajnai (Geothermal Energy Specialization)
Abstract
Acidic wells are reported from several high temperature geothermal fields around the world, including the Geysers, Larderello, Miravalles, Los Humeros, Tatun, Taiwan, Saint Lucia, Windward Islands, and the Krafla. General corrosion rates can significantly influence the production, and in the case of well failures can lead to catastrophic consequences. The designer of the well has to choose whether to use expensive but corrosion resistant materials during the well completion, sacrifice the casing and the production liner and choose a cheaper grade steel or try to solve the corrosion problem by chemically treating the well. This work will try to determine the best potential corrosion resistant materials that can be applied during the completion of a geothermal well, review state of the art information about scaling inhibition due to increased iron concentration and calculate the potential dose rate of caustic injection in the case of well KJ-36.
Gas versus heat transport for low-energy housing
© Tomasz Sasin (Fuel Cell System & Hydrogen Specializtion)
Abstract
The use of energy in the residential sector is among the most significant causes of global warming and greenhouse gas emissions. The majority of energy consumed in households accounts for space heating and the preparation of warm water. The key to decreasing energy consumption is increasing energy efficiency. The most progress in energy efficiency in the residential sector is expected to be made by improving the insulation of buildings and using low-energy equipment. However, in settlements with very high insulation standards, transport of heat becomes senseless as heat losses may be higher than delivered energy. The easiest way to eliminate losses in this case is generating heat directly at the consumer’s location. In the thesis seven ideas are proposed which eliminate heat transport and involve a switch to gas transport or direct electrical energy delivery. In the presented scenarios, all the energy delivered to the settlement comes from renewable energy sources. Four of the concepts were taken into further consideration and an energy efficiency analysis was performed for them. The thesis also presents an up-to-date overview of concepts regarding district heating, efficiency standards for buildings and statistics of renewable energy resources in Germany and the European Union.
The main conclusion reached from this research is that energy distribution by electricity and gases is more efficient than heat distribution and with the use of distributed generation it is possible to completely avoid losses that are present in heat delivery. The biggest problem concerning switching to renewable energy sources is storage of energy during periods of lack of energy delivery from primary sources. In terms of energy efficiency and environmental impacts, the use of biogas reformed in solid oxide fuel cells seems to have the least environmental footprint.
© Marek Skrzypkiewicz (Fuel Cell Systems & Hydrogen Specialization)
Abstract
Solid Oxide Fuel Cells (SOFCs) are a promising source of electricity. They are efficient devices that allow direct harnessing the Gibbs free energy of reactions between fuel and an oxidant. The ongoing project in the Fuel Cell laboratory in Perugia, Italy is a part of their coordination with the Energy Research Center of Netherlands (ECN). This project was devoted to single SOFCs testing, which helps in understanding the influence of different circumstances on the SOFC performance. In this thesis is a detailed outline of the testing procedures and an expanded discussion of the results. The main objectives of this work were to: finish building the single SOFC test bench, create a model that allowed time and gas consumption forecasting for different tests, design the sulphur tolerance system, create a model for cell temperature evaluation, study recent scientific achievements in SOFC with special emphasis on single cells testing, prepare the laboratory testing procedures, perform the tests of the ASC2 Cell by InDEC B.V. The results are presented in graphs in the body of the work and in detailed tables as an appendix. The measurements gave results worse than expected, but the temperature dependence is clear. The conclusions for future development of the test bench are that the temperature measuring should be improved and software development should continue.
Model of energy conversion for wind energy system with hydrogen storage
© Katarzyna Sobotka (Fuel Cell Systems & Hydrogen Specialization)
Abstract
Hydrogen, as a form of long term storage for the excess energy from renewable sources, is a technically and economically viable option. However, the technology is not mature enough to compete with the other renewable energy possibilities. In this thesis, a study based on coupling a wind-turbine with a fuel cell to improve the utilization of wind power is presented.
A part of the energy produced by the wind-turbine is stored in the form of hydrogen and is then delivered for consumption at variable power through a fuel cell. A model was developed to determine the key technical parameters influencing the operation of a wind energy system with hydrogen storage. The model incorporates the simulation results of a 600 kW wind energy system with a 100 kW Proton Exchange Membrane Fuel Cell (PEMFC) and an electrolyzer. Dynamic modeling of various components of this small isolated system is presented for the period from 1.1.2006 to 31.1.2006. In this way, the energy availability can be estimated and is presented for hybrid installations. The study presents the technology of the system for each particular element.
This study is a general introduction for the wind energy system with hydrogen storage. Future studies should be more complex and detailed in order to understand and model the system with greater accuracy and to increase the possibility for the utilization of wind energy to generate hydrogen. This would enhance wind power competitiveness and sustain the continuously changing world energy demand.
Adoption of a carbon dioxide heat pump to geothermal conditions
© Mateusz Tatys (Geothermal Energy Specialization)Abstract
In this thesis the utilization of CO2 heat pumps, together with low-enthalpy geothermal waters or energy of waste water, will be discussed and an attempt will be made to convince the reader that those devices can be used in a simple way to save energy and mitigate global warming.
Basing on the so-called EcoCute air to water CO2 heat pump, a unit which can make use of low temperature geothermal resources, as the external lower heat source will be designed. To reach this target special attention will be paid to the design of a water to carbon dioxide evaporator.
The evaporator type suggested here is of a shell and tube design, with capillary copper tubes which are optimized for incoming water temperatures ranging from 15°C to 40°C and a working fluid pressure of 4MPa. This design will guarantee a small pressure drop on the CO2 side, no leaks, relatively large heat transfer area and will be worth its price.
In this thesis the utilization of CO2 heat pumps, together with low-enthalpy geothermal waters or energy of waste water, will be discussed and an attempt will be made to convince the reader that those devices can be used in a simple way to save energy and mitigate global warming.
Basing on the so-called EcoCute air to water CO2 heat pump, a unit which can make use of low temperature geothermal resources, as the external lower heat source will be designed. To reach this target special attention will be paid to the design of a water to carbon dioxide evaporator.
The evaporator type suggested here is of a shell and tube design, with capillary copper tubes which are optimized for incoming water temperatures ranging from 15°C to 40°C and a working fluid pressure of 4MPa. This design will guarantee a small pressure drop on the CO2 side, no leaks, relatively large heat transfer area and will be worth its price.
An investigation into corrosion problems at the Kalina cycle geothermal power plant in Húsavík, Iceland
© Peter Whittaker (Geothermal Energy Specialization)
Abstract
An overview of the utilization of geothermal energy in Húsavík Iceland is given. Corrosion is discussed in a theoretical manner, with references to the literature for examples of different mechanisms of corrosion. Samples taken from the Húsavík power plant were analyzed by SEM and X-ray EDS, the theory behind this method is discussed and the results are given. Ultimately the investigation into why there were corrosion problems was inconclusive but instructive. Hypotheses discussed in the conclusion, with ways to further investigate them, include: dissolution of micro-constituents in the ammonia environment, galvanic corrosion, stray current corrosion and erosion corrosion. Mild steel and aluminum seem to be inappropriate materials for Kalina cycle systems but several stainless steels (304, 316, nitronic 60 and duplex) as well as 6Al-4V titanium do not appear to suffer from corrosion.
Slow pyrolysis in a rotary kiln reactor: Optimization and experiment [PDF]
© Luka Zajec (Biofuels & Bioenergy Specialization)
Abstract
In this context fits the application of the process of slow pyrolysis of biomass in a rotary kiln reactor with an integrated gas burner of small size for a continuous production of syngas. The objectives of this work are: To run a micropyrolyser in a rotary kiln reactor which was out of use for several years; To connect the micropyrolyser with a gas burner for determination of produced and exhaust gases; To run the pyrolyser in a continuous way for continuous production of syngas; To determine biomass mass flow and mass and energy balance of the system; To perform Proximate and Ultimate analyses of initial biomass and produced char and tar with a gas chromatographer to determine LHV of syngas.
Two tests were performed during the course of this thesis work: A drying test of biomass and a pyrolysis test with a direct combustion of the produced syngas inside a gas burner. An analyzed sample of a gas mixture indicated a lower calorific value of 2,86 MJ/kg of the syngas due to the intake of a considerable amount of ambient air and unintentional leaks and loose-fitting seals. Theoretically, if an anaerobic environment could be achieved inside the micropyrolyser, the produced syngas would have the calorific value of 12,79 MJ/kg, a figure that can also be found in literature. To increase the calorific value of continuously produced gas in a micropyrolyser, the sealing system should be improved.
The work was conducted on a micropyrolyzer located in a pilot plant at the Department of Industrial Engineering, Faculty of Engineering at the University of Perugia, Italy.
