This thesis gives a detailed evaluation of the integration of power plants and post-combustion CO2 capture based on absorption. The study looks at natural gas combined cycles and pulverized coal power plants. Also the absorption process has been evaluated separately, aiming at reducing energy requirements in the capture process. In the first part of the thesis a theoretical part was given on fundamentals of CO2 capture by absorption, power generation, and process integration. Based on this theory, several case studies were defined for each of the three main processes. Simulation models were built accordingly and investigated. Simulation results from the capture process showed that there was a reboiler energy saving potential of 29% and 27% for NGCC and PC plant, respectively, when including vapor compression and absorption intercooling in the capture process. Another interesting observation made was reduced cooling duty in the overhead condenser of the stripper when applying vapor compression.Analysis of steam extraction from the NGCC plant showed it was possible to cover 1 MJ/kg CO2 directly from the HRSG. This steam can be provided directly from the LPB. For duties above 1 MJ/kg CO2 a secondary extraction point was required. In this study the IP/LP crossover was considered the most appropriate point to extract the remaining steam. The efficiency penalty when integrated with the different CO2 capture cases ranged from 7-8%, giving a net plant efficiency of 49.6-50.5%. At part load it was shown that the LPT should be throttled in order to secure constant pressure at the extraction point.For the PC plant the feedwater heat system showed potential in terms heat recovery in the return stream from the capture process. By integrating the return stream with FWH2, energy savings of 11.9% compared to the base case plant were found. Also it was found that the IP/LP crossover pressure should be set to 4.5 bar, since the IPT has the highest efficiency and therefore power production in this unit should be maximized. The final results for the PC plant efficiency range from 30-31.7% and the percentual efficiency penalty was 10-11.7% for the four capture case studies. As was the case for the NGCC plant, the LPT should be throttled when operating at part load.

Det er gjennomført målinger av energibruken til ulike formål i fem leiligheter i Løvåshagen borettslag i Bergen. Tre av leilighetene er av lavenergistandard, mens de to siste er av passivhusstandard. Hovedmålsetningen med oppgaven har vært å framskaffe data for virkelig energibruk i norske passiv- og lavenergihus, slik at det kan gjøres sammenligninger med planlagte verdier. Resultatene viser til dels store variasjoner i energiforbruket i leilighetene. Energiforbruket til oppvarming av varmt tappevann var blant energipostene som viste størst variasjoner. I en av passivhusleilighetene var tappevannsforbruket omtrent dobbelt så stor som i enkelte av lavenergileilighetene. Energitilskuddet fra solfangerne i passivhusleilighetene så også ut til å være mindre enn forventet.Energiforbruket til ventilasjon viste seg å være markant større i lavenergileilighetene enn i passivhusleilighetene. Årsaken til dette er ulikt ventilasjonsaggregat i de to leilighetstypene. Årlig spesifikt energiforbruk i leilighetene er blitt estimert på grunnlag av måleresultatene. Energiforbruket i de to passivhusleilighetene ville gitt henholdsvis karakter C og D på energimerkeskalaen, mens lavenergileilighetene trolig ville endt opp med karakteren C. Forbruket ser generelt ut til å ligge over det som var forventet. Dette gjelder spesielt for leilighetene av passivhusstandard.De store variasjonene i det totale energiforbruket og variasjonen i forbruket til oppvarming av varmt tappevann, viser at energiforbruket i passiv- og lavenergihus i stor grad er brukeravhengig.

Rapporten tar for seg design, bygging og utføring av målinger på en forsøksrigg som skal simulere en passiv varmeveksler til bruk i subsea varmeveksling. Målet med forsøkene er å undersøke varmeovergangen ved forskjellige rørtemperaturer og vannstrømninger.Forsøksriggen som blir designet og bygget består av et vertikalt rør plassert i en vannrenne som har justerbar vannhastighet. Røret blir varmet opp ved hjelp av termoelementer og avgir varme til vannet rundt. Rørveggtemperaturen blir målt ved forskjellige effekter for å finne varmeovergangstallene.Målingene fra forsøkene stemmer godt overens med teorien for naturlig konveksjon ved stillestående vann, men avviker fra teorien allerede ved liten vannhastighet. De målte varmeovergangstallene ved strømning er mye høyere enn de teoretiske beregnede varmeovergangstallene for naturlig og tvungen konveksjon.Det blir oppdaget store usikkerhetsmomenter ved modellen, der hovedproblemet er ujevn varmefluks. Det antas også at det er stor usikkerhet i strømningshastighetsmålingene.På grunn av usikkerhetsmomentene blir det anbefalt å jobbe videre med modellen for å eliminere disse, eller å bygge en ny modell basert på erfaringene fra denne rapporten.

Emissions from road traffic contribute a substantial part of the total CO2 emissions from the transport sector. The amount of passenger cars is rapidly increasing, which leads to an increase in CO2 emissions, even though the average CO2 emissions from new cars are decreasing. This thesis has evaluated the vehicle technologies available at present and examined the measures currently in use to reduce CO2 emissions from passenger cars, focusing on the European Union and Norway. Suggested measures for reduction in CO2 have been discussed. A harmonisation in fiscal taxation system throughout the European Union should be implemented, where a purely and directly CO2 based taxation system would give the largest CO2 reductions.In Norway a large part of the taxation potential is already utilized through registration tax and fuel tax. The taxes should be altered to be purely CO2 based if the objection of a tax is to prohibit the increase in emissions. By using a taxation system that affects a person’s usage of a car, and not the ownership, could make more people seek other means of transportation.A taxation system should not be implemented without measures to expand and upgrade the public transportation. Vast improvements in the Norwegian public transportation is a must if the reduction of CO2 possible and significant.

Nesten all konvensjonell dampkraftproduksjon er avhengig av vann for kjøling. Tilgang til vann er også nødvendig i drift av flere andre delsystemer i et slikt kraftverk. I tillegg medfører integrasjon av CO2 fangst ofte at vannforbruk i et kraftverk går opp. Deler av verden har stor vannmangel og vann bør derfor brukes med omhu. Samtidig med en stadig økende verdensbefolkning, skjerpes fokuset på CO2 utslipp. Det forekommer at den lovende CO2 fangstteknologien basert på oksy-forbrenning, er mindre avhengig av vann sammenlignet med CO2 fangst basert på etterrensing av eksosgassen via kjemisk absorpsjon. To liknende kraftverk med ulik fangstprosess er studert i denne oppgaven. Vannforbruket i et 561 MW oksy-forbrenningskraftverk og et 550 MW kraftverk med etterrensing av eksosgassen, er henholdsvis blitt beregnet. De to kraftverkene sammenlignes deretter opp mot hverandre med hensyn på vannforbruk. Resultatene viser at kjøletårnet utgjør det desidert største vannforbruket i begge kraftverk. Vanntap grunnet fordamping er dominant, men nedblåsing av urenheter er også en betydelig årsak til vanntap når en middelmådig vannkvalitet brukes. CO2 fangst basert på etterrensing av eksosgass har et betraktelig større kjølevannsbehov, noe som resulterer i 17,8% høyere vanntap i kjøletårnet sammenlignet med oksy-forbrenningskraftverket. Det nest største vanntapet skjer ved fjerning av SOx fra eksosgassen (FGD). I luft-fyrte kraftverk er fordamping av vann hovedårsaken til vanntap i FDG-systemer. Andre vanntap er knyttet til produksjon av gips og til nedblåsing av urenheter. En høy vanndampandel i røykgassen fra oksy-forbrenning eliminerer fordampingstap, fordi røykgassens duggpunkt ofte ligger under driftstemperatur til FGD systemet. I denne studien, utgjorde vanntapet i FGD prosessen i etterrensing kraftverket åtte ganger mer enn i oksy-forbrenningskraftverket. Et scenario hvor kraftverkene er lokalisert nært havet og sjøvann brukes som kjøling er også studert. Beregningene viser at oksy-forbrenningsanlegget bare bruker 17% av det vannet som forbrukes i etterrensingskraftverket. Denne trenden er også synlig i noe mindre grad, i tilfellet hvor kjøletårn er brukt. En betydelig mengde kondensat er tilgjengelig i oksygenproduksjonen og CO2 utvinningsprosessen, fordi vann tilføres systemet via inntak av fuktig luft, fukt i brenselet og via hydrogen bundet i brenselet. Gjenvinning av vann kan bidra til betraktelig reduksjon det totale vannforbruket i begge kraftverkene.

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.