The purpose of this thesis was to examine different technologies, which enhances the CO2 partial pressure in the flue gas from the natural gas combined cycle. A base case has been created as a reference for comparison of the other cycles. The base case includes a MEA capture plant with a reboiler duty of 3,6 MJ/kg CO2. To simulate the process in this thesis HYSYS and GT PRO have been used as simulation tools. The thesis has also looked into ways of extracting steam from the steam cycle to be used in the reboiler. The chosen extraction point was the crossover between the intermediate-pressure turbine and the low-pressure turbine, the steam was saturated with water from the low-pressure boiler and have a pressure and temperature of 3,6 bar and 140 °C into the reboiler. Four different technologies have been evaluated in this thesis; a natural gas combined cycle with the use of exhaust gas recycle and, three elevated pressure cycles; post-compression CO2 capture, post-expansion CO2 capture, and tail-end CO2 capture. These processes have been compared against each other with regards to the net plant efficiency, absorber size at the capture plant, and the technological maturity. The most promising of these technologies is the natural gas combined cycle with exhaust gas recycle and the tail-end CO2 capture processes, with respectively 52 % and 51,7 % net plant efficiency. The smallest absorber size is achieved by the use of post-compression CO2 capture, with a diameter of 2,9 m and a height of 10,5 m. The elevated pressure cycles have also been tested with the use of MDEA as solvent in the capture plant. By use of elevated pressure and MDEA the reboiler duty was reduced to 2 MJ/ kg CO2.

Annual operating costs for buildings are a substantial cost in a lifetime. It is therefore of interest to try and reduce these costs. A large fraction of this cost today as the buildings become more and more energy efficient is the cost of hot tap water. The study in this report looks into the potential for energy savings from grey wastewater. It is here looked at the amount of energy which can be recovered from hot water leaving the building and reused for pre heating of hot tap water and heating of building. The unit which would recover this energy is referred to as the grey-water heat recovery unit in this report. A residential building with three floors where each floor has one washing machine, one shower and one dishwasher has been as the case building for the report. The total living area of the building is 450 m2. In the case building used in this report as much as 17.1 % of the total used energy goes to heating of hot tap water. By installing a heat recovery system which can recover some of the energy stored in the used hot water which leaves the building, this this could be reduced to 10.9 % of the total used energy according to simulations done in SIMIEN. There are also possibilities of using this energy for heating of the building as well as pre heating of hot tap water. There are a few different solutions for implementing a grey-water heat recovery unit which could give different energy recovery between 2 716 kWh/year to 3 759 kWh/year. The best solution would be to connect the grey-water heat recovery unit to pre-heating of hot tap water, heating of the building as well as installing an accumulation tank to store recovered energy in. The most simple solution which would give the lowest amount of recovered energy would be to just connect the grey-water heat recovery unit to pre heating of hot tap water. In this report two different simulation programs have been used, EnergyPlus and SIMIEN, to find what impact the energy reduction would have on the building and to see if the simulations would correspond to the theoretical estimates done in this report. The theoretical estimates based on equations for heat recovery and measured data for energy use in the case building gave a little bit better results than the simulated results for the same case building. Although there is a difference both gave a positive indication that a heat recovery unit would not only reduce the energy consumption but also reduce the annual operating cost of a building. The investment cost for a heat recovery system could be a bit large for small buildings compared to the annual savings but for larger buildings the investment cost could be substantially higher. Regarding the energy as much as 87.7 % of the energy stored in the grey-water could be recovered for a system with an accumulation tank and a connection to the buildings heating system. For a system without the accumulation tank and district heating as the energy source it would have a theoretical efficiency of 76.7 % and a simulated efficiency of 63.3 % when simulated in EnergyPlus.

In a world where energy demand, population, and environmental concern are increasing by the day, the use of solar energy and other renewable energy sources becomes ever more important. Most of the African population lives in rural areas and uses wood as primary energy source for cooking. The wood, however, can be replaced by the energy in the abundant sunshine most African countries experiences and used in solar cookers. However, the biggest disadvantage of most common solar cookers available today is that they are dependent on direct solar radiation to work. This makes them vulnerable to the intermittent nature of the sun and limits the cooking to the sunny hours of the day. In this thesis, a possible solution to that problem area is examined. A solar energy heat storage for vapour based solar concentrators is designed, constructed and analysed with cooking of the traditional Ethiopian bread injera in mind. The storage consists of an aluminium bolt with salt filled cavities that has working fluid (steam or oil) running through it. The energy stored during the salt melting (latent heat) is released at constant temperature between 210°C-220°C which is the melting temperature of the salt, and the temperature needed to cook injeras. One experiment was performed with heat transfer oil as working fluid, but did not yield any results due to air bubbles that prevented circulation. Two experiments were done with steam as working fluid. The first experiment measured the discharge of the storage which was found to be a temperature fall from 221.8°C to 50°C during a time span of 85 hours. The other experiment aimed for boiling of one litre of water, but the highest temperature reached was 70.9°C. However, several modifications can be done to improve the storage capacity and cooking procedure, as for instance increasing the amount of salt.

Sammendrag Trusselen tilknyttet til globale klimaforandringer er en av nåtidens største utfordringer, og den største miljømessige, sosiale og økonomiske trusselen verden står ovenfor. Ved å anvende husdyrgjødsel for produksjon av fornybar energi i form av biogass, kan utslippene av drivhusgasser reduseres, på samme tid som lokale ressurser utnyttes på en bærekraftig måte. I denne masteroppgaven har et Excel-basert verktøy blitt utviklet for å beregne transportkostnader, gjødsel – og biogasspotensiale, samt kostnader for råbiogassproduksjon, oppgradering og komprimering av biogass på Ørland. Gjødsel – og biogasspotensiale på Ørland er beregnet til henholdsvis 47 815 tonn/år og 22,87 GWh/år. Og ved bruk av Geografisk Informasjonssystem (GIS) er det funnet optimal plassering for anlegget. Vektet gjennomsnittsavstand i luftlinje fra gårdene til anlegg er beregnet, og basert på denne overordnede analysen er det forutsatt at alle de 65 gårdene på Ørland kan bidra på et stort fellesanlegg, hvor gjødsel og biorest vil bli transportert med lastebil. Totalenhetskostnad for råbiogassproduksjon, oppgradering og komprimering er beregnet til 39,9 øre/kWh. Etablering av et stort fellesanlegg på Ørland er, i teorien, et lønnsomt prosjekt. Et mulig bruksområde for den produserte biogassen er å forsyne gassbusser i Trondheim med komprimert biogass (CBG), hvor biogasspotensialet fra Ørland har mulighet til å forsyne 64 busser per år. CBG vil bli transportert til sluttbruker ved bruk av tankbil. Klimaeffekt ved å gå fra konvensjonell gjødselhåndtering til biogasshåndtering er 2845 tonn CO2-ekvivalenter/år, som inkluderer utslipp ved transport, gjødselhåndtering og overgang fra dieselbusser til gassbusser.

This thesis gives a detailed evaluation of the part-load operation of a natural gas-fired combined cycle with an absorption plant for capture of CO2. The study looks into each of the processes related to the plant. Both the combined cycle and the absorption process are investigated separately, in terms of their part-load behavior, and a recommendation on how the total plant should be operated at part-load is given. The first part of the current work was a theoretical study of combined cycles, absorption plants and the integration between those. Both design and off-design models have been looked into. Based on the theory, a reference plant was designed and considered as a starting point for the part-load investigation. By means of simulation models and the theory, several parameter changes have been analyzed for each of the processes. The investigation of the part-load operation of the power plant indicated a significant net plant efficiency saving if inlet guide vanes were used to reduce the air flow into the gas turbine compressor, in combination with fuel reduction. The most recommended control strategy of the inlet guide vanes regulation was an almost constant target exhaust gas temperature relative to the design point. A higher target exhaust gas temperature obtained marginally better combined cycle efficiency, but problems could occur related to very high temperature gradients in the heat recovery steam generator. Analysis of the absorption process showed a dramatic reduction in the liquid circulation rate that provided the lowest reboiler duty, as the gas turbine load was reduced. The reduction in liquid flow rate into the absorber was about 30% relative to the flow rate in the design point, for a gas turbine load of 60% with an almost constant exhaust gas temperature. Regarding problems due to insufficient wetting of the packing material in the absorber, a restriction on the liquid flow rate at part-load operation could be profitable. A relative increase in total reboiler duty of 5% was detected from the simulations if a constant liquid flow rate restriction was used, compared to 30% reduction of liquid flow rate, at 60% gas turbine load. For the integrated power plant and absorption process, steam was preferable extracted from the crossover between the intermediate-pressure- and low-pressure turbine at 3,5 bar. This extraction pressure was independent of the part-load operation, and the low-pressure turbine should be throttled in order to meet the required steam extraction pressure at part-load. The design power plant with CO2 capture obtained a total plant efficiency of 53%, disregarded mechanical losses- and compressor work in the capture plant. At 60% gas turbine load with almost constant exhaust gas temperature, the respective net plant efficiency was about 49% dependent of the liquid flow rate in the absorber. A efficiency loss of 0,3% percent points were detected if a constant liquid flow rate restriction was used, compared to 30% reduction of liquid flow rate at 60% gas turbine load.

I denne oppgaven har en Kaplan turbin produsert i Afghanistan blitt undersøkt. En fullstendig virkningsgradanalyse er gjort i laboratoriet, på to av fire løpehjulsvinkler. Like før innløpet til turbinen er det et 90 grader bend, som har blitt simulert i Ansys Fluent. Forbedringer av bendet er foreslått. Turbinen er laget av Remote HydroLight for bruk i Afghanistan. Målet med turbinen er at oppbygningen er enkel nok til at innbyggerne kan produsere og vedlikeholde turbinen på egenhånd. Det betyr at turbinen må være modifisert i forhold til en tradisjonell Kaplan turbin. Sagt med andre ord, er et enkelt design viktigere enn en høy virkningsgrad. Forenklingene av turbindesignet tatt i betraktning, er beste virkningsgrad høy; 85.32 % for løpehjulsposisjon 1, og 87.75 % for posisjon 2, med en usikkerhet på 0.5 %. Reduserte parametere er brukt. Dersom fallhøyden økes, ser man en liten økning i virkningsgraden. Dette kan skyldes lavere friksjonstap ved høyere Reynolds tall. For posisjon 2 ser man den motsatte effekten; virkningsgraden minker litt med høyere fallhøyde, for høy volumstrøm. Dette kan være fordi høyere volumstrøm gir høyere tap i bendet, fordi strømningsprofilen blir mer ujevn. Løpehjulskovlene har fire ulike posisjoner, mens ledeskovlene ikke kan justeres. Posisjonene er markert med små hakk på bladene, og å finne eksakt samme posisjon når skovlene har blitt flyttet på er vanskelig. Målinger gjort på samme skovlåpning gir derfor varierende resultat. Bendet har to strømningsrettere og effekten av disse har blitt simulert. Simuleringene viser at den nedre strømningsretteren har en stor positiv effekt på strømningen i forhold til å ikke ha strømningsrettere. Den øvre strømningsretteren viser liten eller ingen effekt på strømningen og kan derfor bli fjernet. Dersom den nedre strømningsretteren flyttes mot høyre, er den positive effekten på strømningen enda større, ved at den akselererer strømningen i den indre delen av bendet. Simuleringer har blitt sammenlignet med Pitot-målinger gjort i laboratoriet, og de viser de samme tendensene i strømningen.

This thesis assesses several value chains for bioenergy production in Norway and combines these representing two Norwegian scenarios. The environmental impacts are assessed using the methodology of life cycle assessment (LCA). A complete assessment of climate change impact has been a core task, and biogenic CO2 emissions are accounted for throughout the value chains investigated. Surface albedo effects are included in the assessment of forest resources. In addition to global warming potential, the value chains are assessed for three other impact categories; acidification potential, particulate matter formation potential and terrestrial ecotoxicity potential. Life cycle inventories are constructed for a set of six feedstocks, seven treatment options, ten energy conversion options and three energy distribution choices. The different options are then combined to 80 feasible value chains. Transport is included throughout all the value chains. All inventories are assembled to represent Norwegian conditions. Energy flows for the different value chains investigated are found to represent the current bioenergy system, with a potential increase for each value chain towards 2020 - representing the alternative scenario. Results are generated for the individual value chains, the reference scenario and the alternative scenario. The results show large differences between the different value chains. Energy wood and waste wood are the most beneficial feedstocks for bioenergy production, highly dependent on both the GWPbio factors utilised and inclusion of surface albedo effects. Pelletising is the pre-treatment option resulting in the lowest GWP, while integrated torrefaction and pelletising results in the highest GWP. Overall, a CHP plant with electricity demand is the most advantageous conversion route. A stand-alone thermal electricity plant has the definite highest impact, mainly because of low conversion efficiency. Heat distribution shows high impacts compared to electricity and steam distribution, and the resources resulting in lower impacts is therefore recommended as inputs for such units. Generally, handling of biogenic CO2 emissions is of high importance. The same is the case for surface albedo effects, changing the GWP for forest resources considerably. CHP plants are recommended for electricity production from biomass, and use of TOP, forest residues and stemwood are recommended to take place in the same conversion technology. The environmental impacts from a CHP plant is low, and TOP, forest residues and stemwood show high GWP. The GWP from energy wood, wood waste and pellets are low, and are therefore recommended for use in district heating plants. As stand-alone electricity production is not recommended, the GWP from a district heating plant is limited with the use of the mentioned resources. Pelletising is recommended for pre-treatment of Norwegian biomass because of low climate change impacts. The Norwegian Government has put forth ambitious goals to reduce the GHG emissions substantially towards 2020 and become climate neutral by 2030. The reference scenario assessed show a GWP of 134 grams CO2-equivalents per kWh, while the scenario for 2020 results in a climate change impact of 136 grams CO2-equivalents per kWh. Based on this, Norwegian bioenergy can offer a means to reduce the GHG emissions towards 2020, but because of considerable GWP from biogenic CO2 emissions, bioenergy should not be pursued for a goal of becoming climate neutral by 2030.

Oxy-combustion is a promising technology for capturing CO2 from coal based power plants. In a coal based oxy-combustion power plant coal is combusted with high purity oxygen in order to produce steam for power production. The flue gas from this combustion consists mainly of H2O and CO2, but it will also be polluted with other components due to in-leakage of air, impurities in the coal, excess oxygen in the combustion and diluted oxygen supply. The main separation processes in such a power plant takes place in an air separation unit (ASU) where oxygen is separated from nitrogen, and in the compression and purification unit (CPU) where the CO2 in the flue gas is separated from the H2O and the other pollutants and compressed for transportation and storage. The introduction of these two units causes an efficiency penalty to the power plant. In this master thesis it is studied if and how heat integration of low temperature heat can decrease the efficiency penalty related to the ASU and CPU. The base case power plant is a coal based oxy-combustion power plant with a 567MW net power output and a thermal efficiency 31,32%. The heat sources considered are the heat which is removed by intercoolers in the compressors in the ASU and CPU, and waste heat from the flue gas exiting the steam generator. It is also studied if lifting the temperature level of the compression heat by compressing adiabatically will increase the potential for heat integration. Three main cases are considered for integration; integrating compression heat and waste heat from the flue gas with the feedwater system in the steam cycle of the power plant, integrating compression heat or flue gas heat to increase preheat of the recycled flue gas and oxygen entering the combustion, and integrating waste heat from the flue gas with a CO2 Rankine Cycle. It was found that integration of compression heat with the feedwater can increase the thermal efficiency of the power plant by 1,19% if the compressors are operated with intercooling and 1,49% if adiabatic compression is utilized. If the flue gas heat is also integrated, the efficiency increases by 1,72% with intercooled compression and 1,96% with adiabatic compression. Utilizing flue gas heat to preheat the recycled flue gas and oxygen can give efficiency increases in the region of 0,3-0,7%. The same applies if compression heat is utilized for this preheating. Since the temperature level of the recycled flue gas and oxygen is low, it is not necessary to compress adiabatically. If the waste heat in the flue gas is integrated with a CO2 Rankine cycle, efficiency improvements in the region of 0,47 to 0,51% can be obtained. The integration projects discussed in this report will increase the complexity of the system and may increase equipment costs. It is necessary to do a more detailed analysis of the heat exchanger networks required to reach the energy targets and heat exchanger surface area requirements in order to properly estimate the costs and choose the optimal configuration for integration. However it is recommended that future studies focus on the use of adiabatic compression heat as it has been shown to give significant increases in efficiency. Whether or not to include the flue gas in the integration depends on whether or not it is cost-efficient to introduce corrosion resistant heat exchangers to cool it below the acidic dew point.

Carbon Capture and Storage has large a potential to mitigating the CO2 emissions caused by fossil fuel powered power plants. CCS reduces the energy efficiency of the plant and increases the demand on chemicals and infrastructure. It is though not only the direct emissions from the power plants that have an impact on the environment. The entire supply chain of the power plant has an impact, and it is therefore necessary to evaluate the entire life cycle of the plant. This thesis consists of a full process LCA of post-combustion absorption based carbon capture and storage (CCS) technologies for both coal power plants and natural gas power plants. The assessed CCS technologies are based on the solvents MEA, MDEA and chilled ammonia. MEA is the most commonly used solvent in post-combustion capture, while MDEA and chilled ammonia represents novel CCS technologies that are still under development. It was shown that a 90% capture rate was possible for all of the assessed capture technologies. It was further shown that the total global warming potential (GWP) could be decreased with above 60%. 90% reduction is not possible because of indirect emissions in the supply chain. The reduction in GWP comes at a cost of decreasing energy efficiency, which further leads to an increase in consumption of materials and infrastructure. This causes the non-GHG related impacts to increase, compared to a base scenario without CCS. CCS technology based on MDEA was calculated to be the technology with the lowest impact, mainly because it has the lowest energy requirement. Chilled ammonia was assessed as the technology with the largest impacts. The reason for this is that the chilling process is very energy intensive and therefore decreases the efficiency more, compared to the other technologies assessed. Also the large emissions of ammonia have a large impact on the acidification potential and the marine eutrophication potential.

Stortinget legger grunnlaget for en opptrapping av arbeidet med å redusere klimagassutslippene i Norge med Klimameldingen og Klimaforliket, som fører til stadig strengere krav og økt fokus på energibruken til bygninger. I denne masteroppgaven blir det sett på et 3 000 m2 stort kontorbygg som bygges på kysten i Mandal kommune, og som skal tilfredsstille passivhusstandarden. Det benyttes en ny løsning for varmeavgiver i det vannbårne oppvarmingssystemet, nemlig takvarmepaneler som skal integreres i YIT sitt KlimaTak. EnergyPlus er et dataprogram for energianalyse og termisk simulering, og er det simulerings-programmet som benyttes i denne oppgaven. Det blir bygget en simuleringsmodell av kontorbygget med grunnlag fra arkitektoniske plantegninger, med oppvarmingssystem og med tilhørende takvarme og ventilasjonssystem. Simuleringsmodellen blir kjørt med ulike energikilder til det vannbårne oppvarmingssystemet, der følgende kombinasjoner blir undersøkt: 1. Direktevirkende elektrisitet 2. Luft-veske varmepumpe + elektrisitet som spisslast 3. Vann-veske varmepumpe med energibrønn + elektrisitet som spisslast 4. Solfanger + luft-veske varmepumpe + elektrisitet som spisslast 5. Solfanger + vann-veske varmepumpe med energibrønn + elektrisitet som spisslast Det er varmepumpe med R410a som arbeidsmedium som benyttes, og vann-veske varmepumpa benytter dessuten en energibrønn med en aktiv borehullsdybde på 1 000 m. Oppvarmingssystemet som kom best ut i simuleringene og den økonomiske analysen, var systemet med luft-veske varmepumpe og direktevirkende elektrisitet som spisslast. Dette systemet hadde en investeringskostnad på 246 000 kr og en årlig energisparing i forhold til referanse-systemet med kun direktevirkende elektrisitet som oppvarmingskilde på 57 579 kWh/år. Systemene med solfanger kom dårlig ut på lønnsomhetsanalysen fordi energien fra solfangeren bidro for lite til dekning av energibehovet til bygningen. Solfangersystemet med en 100 m2 solfanger leverte under 1 300 kWh/år, og vil av den grunn ikke kunne rettferdiggjøre en innkjøpspris på 305 000 kr. Om den tapte energien fra solfangeren, som utgjør over 18 000 kWh årlig, kunne utnyttes helt eller delvis, kunne dette utgjøre større utslag på energibruken til oppvarmingssystemet. Behovsimuleringen av kontorbygget der kun oppholdssonene ble klimatisert og det ble benyttet utvendig solavskjerming med styring på innetemperatur og solinnstråling, resulterte i et årlig energibehov på 356 026 kWh/år. Dette er et stort avvik fra tilsvarende simulering i SIMIEN. Det ble også forsøkt simuleringer med varierende styring av innetemperaturen i kontorbygget. Behovsanalysen benyttet en nattsenking av innetemperaturen på inntil 5 ºC senkning utenfor arbeidstid, mens det også ble forsøkt å holde innetemperaturen på konstant 21 ºC over hele døgnet. Det ble imidlertid funnet at en økning i energibehovet på 19 973 kWh ved å gå fra nattsenking til konstant innetemperatur spares inn for oppvarmingssystemene med varmepumpe, fordi en får et mer stabilt effektbehov og dermed bedre arbeidsvilkår for varmepumpa.