As a consequence of increased government efforts to reduce local Norwegian CO_2-emissions the development of small distributed generators have increased. This development is assumed to continue, but at an increasing incremental cost due to the inferior profitability of remaining prospects. To maintain profitability of smaller and high cost distributed generators, cost savings must be implemented. Quality of supply is a significant factor in determining potential profitability. Hence, a significant potential in cost reduction lies in increasing quality of supply. This can be achieved by utilizing the decentralized nature of these power producers by enabling intended island operation. By enabling these generators to run in intended island mode, they are able to supply their local grid with power when fallout of the main grid or other components occurs. This increases the uptime for local customers and therefore increases quality of supply. Five different grids are modeled in PowerFactory based on collected empirical data for the evaluation of the potential for islanding in Norway. With these models different cases utilizing islanding schemes are simulated and the reliability of these configurations compared to a base case representing normal operations. The results from this analysis suggest big reductions in the reliability indices “Energy Not Supplied” and “System Average Interruption Frequency” are possible. In the thesis the reductions achieved are in the 10%-60% range of the base case. The estimated savings earned from increased reliability of supply does not justify the assumed investment needed, but the numbers are not conclusive. Better estimates of expenses and assessing other grids with better prerequisites for islanding could indicate to be profitability.

I denne oppgaven er det sett på hvordan energibehov og lys i bygninger påvirkes av solavskjerming.Solavskjermingens oppgave er ikke bare å skjerme for sjenerende lys. Økt fokus på passivhus fører til at solavskjerming i større grad enn tidligere også må skjerme for varme. Det vil være ønskelig å stenge ute varme samtidig som en slipper inn lys.Ved hjelp av simuleringer er det sett på hvilke utslag endring av ulike egenskaper i glasset gir på energibehov og belysningsstyrke i bygninger. Det er også sett på ulike glassbelegg, bygningsutspring og himmelretning. Av aktive solavskjerminger er det sett på persienner, da både utvendig, mellomliggende og innvendig persienne og styring av disse. Simuleringene er gjennomført med tanke på skolebygg, men er overførbare til andre bygningskategorier.De viktigste resultatene av simuleringene er: •Glassets egenskaper: o g-verdi virker inn på  energibehovet til oppvarming og kjøling  effektbehovet til kjøling o u-verdi virker inn på  energibehovet til oppvarming o t_v-verdien virker inn på  belysningsstyrke  energibehov til belysning •Bygningsutspring virker inn på o belysningsstyrke o energi og effektbehov til kjøling • Himmelretning virker inn på o energibehov til både oppvarming, kjøling og belysning o belysningsstyrken • Persienne: o Utvendig persienne gir  høyere energibehov til oppvarming enn innvendig persienne  lavere energi og effektbehov til kjøling enn innvendig persienneKonklusjon: • Rom med kjølebehov bør o ha lav g-verdi o ha utvendig persienne o legges mot nord •Rom uten kjølebehov bør o ha lav u-verdi o ha høy g-verdi o ha innvendig persienne o legges mot sør • Rom med ønske om høy belysningsstyrke bør o ha høy t_v-verdi o legges mot sør

An analysis incorporating different principles for determination of the electricity mix and the subsequent environmental characteristic.

There is a growing demand for increased electricity transfer capacities between the countries surrounding the North Sea. The increased capacities will enable easier integration of intermittent renewable energy sources, decrease the need for balancing power, increase power trade and competition, and increase security of supply across the region. Interregional offshore grid connections are required if large scale deployment of deep sea, far from shore offshore wind energy in the North Sea is to take place. The WINDSPEED research project has resulted in proposals of realistic scenarios for large scale deployment of offshore grid and wind energy in the North Sea. In this study the environmental impacts of an interregional meshed offshore grid as proposed by WINDSPEED have been assessed. Environmental impacts of the offshore wind farms, which may be connected to the grid, have been included in the assessment as well, completing the system boundaries.The methods used to quantify the environmental impacts are process-based life cycle assessment (LCA), input-output assessment (IOA) and tiered hybrid LCA, with main focus on the results of the latter. Four offshore grid scenarios have been assessed, with and without offshore wind farms connected. The offshore grid is primarily composed of 450 kV HVDC technology for long distance transmission, based on the HVDC cables used in the NorNed connection. Wind farms are deployed far from shore (requiring much sea transport and long distance grid connections) and at an average of 43.9 meters depth (requiring large bottom-mounted foundations for the wind turbines). These requirements make the environmental impacts of deep sea, far from shore offshore wind energy substantially higher than for both close to shore offshore wind energy and onshore wind energy.The environmental assessment of the interregional meshed offshore grid found that the largest contribution to environmental impacts is from manufacturing and installation of HVDC cables. Sea transport required for installation of components and operation and maintenance contributes between 5 and 25 percent to most impact categories. The electrical equipment (converters, breakers and switchgear) required by the grid has a quite varying contribution, from almost none to some impact categories to about 35 percent to climate change impact. The environmental assessment of the deep sea, far from shore offshore wind energy, finds that the largest contributors to environmental impacts are the wind turbines. But the other components required – deep sea foundations, offshore grid and sea transport for installation, operation and maintenance – makes the environmental impacts caused by it around twice as high as for onshore wind energy installations. Total climate change impacts were found to be 42.9 g CO2-Eq/kWh; the grid is responsible for 11, foundations 31 and sea transport 9 percent of that. The largest impacts of deep sea, far from shore offshore wind energy as compared to other relevant energy sources are to the impact categories freshwater ecotoxicity, human toxicity and metal depletion. The impacts to these categories are many times larger, up to almost 20 times, compared to other relevant fossil fueled energy sources. The impacts to the other impact categories are substantially lower.The results indicate that the environmental impacts caused by an interregional meshed offshore grid in the North Sea are substantial; it needs to be considered an important part of an environmental assessment of deep sea, far from shore offshore wind energy. On the other hand, the environmental costs are probably not so high that they outweigh the potential benefits of such offshore grid connections. It may in fact lead to net environmental gains because of a decreased demand for fossil balance power. As for large scale deployment of deep sea, far from shore offshore wind energy the environmental benefits as opposed to relevant fossil alternatives are obvious, but, including the significant disadvantages of intermittent energy supply and high monetary costs, overall gain to society is harder to predict.

This work involves the study of heating systems that combine solar collectors, geothermal heat pumps and thermal energy storage in the ground. Solar collectors can reduce the electricity use in these systems by reducing the operation time of the geothermal heat pump and by increasing the ground source temperature. These systems can be designed in many ways, consequently the complexity is high. The purpose of this study has been to develop simulation models to study the behavior of these systems, with emphasis on the thermal energy storage in the ground. A simulation tool with several models has been developed in the simulation software TRNSYS based on the proposed heating system at the GEL under the metrological conditions of Shanghai. The program was used for an intensive simulation study, in which the interaction with the borehole heat exchanger, the geothermal heat pump, the evacuated tube collector and the load requirements could be analyzed. A base case was developed to make it possible to vary and compare the design parameters of interest, such as the ground storage volume, the flow rate of the solar collector and the solar collector area. The base case was based on the design parameters of the GEL. The GEL was used as reference building and was simulated in TRNBuild with the thermal characteristics of the building material. From the simulations the heating demand of the building could be obtained and the building model could later on be used as a heat load for the other simulation models. The results showed that the there were heating demand from November to March. The four operation modes of the proposed heating system at the GEL were presented. All of the operation modes were simulated in TRNSYS. The four operation modes were solar thermal ground storage, solar direct heating, direct heat exchange with the ground storage and geothermal heat pump. The operation modes worked in two different seasons, storage season and heating season. The ground storage mode was studied thoroughly by varying the parameters of interest. To test the significance of the borehole configuration, the storage volume was kept constant and the number of boreholes and the borehole spacing were varied. It was found that a compact pattern with a high number of boreholes and small borehole spacing is favorable for borehole thermal energy storages. The performance of a ground storage is directly linked to the storage size. The solar collector efficiency is highly dependent on the return temperature of the storage. It was decided to continue to work with a compact pattern of the storage, rather than the base case of the GEL. This is because this kind of storage showed the most promising storage efficiency and also reached a high ground temperature during storage season.Simulations of the heating modes showed that the solar direct heating mode, the direct heat exchange with ground storage mode and the geothermal heat pump mode can each cover 37%, 25% and 38% of the heating demand respectively. For the simulations of the geothermal heat pump it was shown that the borehole depth is a very important factor for the system performance. Too short borehole depth will cause unstable and too low temperatures at the inlet of the evaporator. To compare the electricity use of a geothermal heat pump system with and without solar collectors there were also performed simulations for a traditional geothermal heat pump system. Results showed that 26.1% of the electricity consumption could be saved. The savings was mostly due to the reduced operation time of the heat pump, since other heating modes could be used. The studies showed that due to the complexity of such systems it is very important to perform simulations to optimize the performance. There are many factors that play an important role since there are so many components involved. The simulations showed that sizing of the system is critical for the system performance.

In this thesis, a novel open cycle desiccant dehumidification system is experimentally studied. The system is installed and operated at Shanghai Jiao Tong University (SJTU) as part of the Green Energy Laboratory (GEL) initiative. The system uses two-stage desiccant dehumidification as well as regenerative evaporative cooling for chilled water production. The purpose of the thesis is to evaluate the system performance during different ambient and operational conditions. The investigated system has great potential regarding the environmental aspect of HVAC system solutions. The system is more energy efficient compared to conventional air conditioning systems and uses solar thermal power provided by evacuated tube solar air collectors as the main source of energy. Therefore, this type of system can contribute in reducing the use of non-renewable energy sources.A lot of experiments have been performed from June to July 2012 during varying ambient conditions. As a first step, the necessary regeneration temperature level is established. The results show that this temperature should be in the range of 70-75˚C or higher to be able to achieve desired dehumidification effect. Then, experiments regarding the overall system performance during different ambient temperature and humidity conditions are performed and analyzed. The results show that the system excels good performance during periods of high ambient humidity and is capable of achieving average COPth and COPel around 0.8 and 5.7 respectively. The total dehumidification efficiency is approximately 58% and is proven to vary with respect to the regeneration temperature, where increasing regeneration temperature results in higher amount of moisture removed from the processed air. The solar collectors providing heat to the regeneration air has an efficiency of 47-60% depending on the available level of solar radiation intensity. During periods of low intensity it is proven that the heating system needs assistance from an auxiliary device to be able to generate a sufficient temperature level. The evaporative cooler producing chilled water is capable of providing water at a temperature below 21˚C during periods of high ambient temperature, and temperatures below 16˚C if the ambient temperature decreases. The achieved dehumidification and cooling capacity of the desiccant system makes it possible to provide qualified supply air with temperature in the range of 20-26˚C and absolute humidity below 12 g/kg. Also, an experiment with the purpose of investigating the newly installed second desiccant wheel is carried out. The system is operated with only the second wheel running and the results show that the dehumidification performance is very good when the second wheel provides the first stage dehumidification. Lastly, experiments investigating the impact of the pre-cooling heat exchanger is performed and analyzed.

Nitrogen oxides (NOx) are formed by oxidation of nitrogen during the combustion process, and production rate is highly affected by flame temperature. NOx is regarded as a local pollutant causing smog, acid rain and health complaints, and strictest emission regulations are found in urban areas. Reduction of NOx emissions from gas turbines can be achieved by modifying the combustion process or by exhaust gas clean up. Several technologies are already commercial available, but there are still a great many being developed. Increased focus on the environment also forces manufacturers to improve existing technology. In this report, different NOx abatement technologies are looked into, and an optimal solution for the coming gas turbines on Skarv Idun is presented. Different techniques are compared in terms of thermal efficiency, emissions, maintenance requirements, load acceptance and rejection, engine stability and reliability and availability. Application and suitability of available technologies for reducing NOx from the selected gas turbines is discussed, and user experience for these is collected. It is showed that all technologies influence operation of the gas turbines to some extent, either by increasing/decreasing efficiency or by affecting engine stability. They also differ in their ability to reduce NOx emissions over the entire load range. Due to weight and space restrictions on offshore installations, limited technologies are suitable for platforms and boats. Gas turbines installed offshore are usually aero-derivative engines with high efficiency and relative low emissions of CO2. This year, Norwegian government introduced a NOx tax in order to reduce NOx emissions from the petroleum industry. Operators are forced to use best available technology, and dry low emission control (DLE) is the only one considered qualified as far as NOx is concerned. DLE is also chosen as the optimal solution for the planned gas turbines on Skarv Idun, due to small operational impacts and positive experience from existing fields. It is however recommended to allocate space in case a new and better combustor with lower emission levels is developed. Looking at a longer perspective, Cheng technology including steam injection into the gas turbine combustor seems very promising for NOx abatement.

High concentrations of sediments is a serious problem for hydropower stations in the Himalayas and the Andes Mountains. For run-of-river power plants sediment causes heavy erosion even with settling basins. This leads to reduced operating hours and high maintenance cost. In addition, the original design experienced problem with heavy cavitation.The objective of this master thesis is to carry out new hydraulic design of the runner and guide vanes of the existing Francis turbines in La Higuera Power Plant with reduced velocity components. To achieve this the cause of the heavy cavitation, which made the turbine fail, has to be established.Results from numerical simulations indicates a low pressure zone causing heavy leading edge cavitation is the reason for the turbine failure. The off-design operation has made the cavitation even worse.To carry out a new design, the in-house design software Khoj was used. Some new parameters, like blade leaning, were included in the program. Blade leaning is an important tool for pressure balancing the runner blade. Further, a parameter study was carried out to investigate the effect of blade leaning, blade angle distribution and blade length. The numerical simulation indicates proper pressure balancing could have avoided the cavitation problems and a new design should have an X-blade shape. Because the power plant is already built, the number of variables is limited. The rotational speed, inlet and outlet diameter remained constant. This made it impossible to significantly reduce the relative velocities. Therefore, coating of all wet surfaces is proposed to reduce the effect of erosion.The main objective for this thesis has been to identify the cause of the turbine failure and develop a new design to fit in the existing power plant. Complete 3D-drawings of the design, including runner and guide vanes, has not been made due to lack of time.

This thesis is a feasibility study of the possible application of magnesium alloys forfuture magnesium-ion batteries. It investigates dierent alloys and characterizesthem with respect to internal resistance, overpotentials and the reversibility of theelectrochemical reaction. SEM and EDS studies of used electrodes have also beencarried out. It has been showed that alloys, easier to handle and at a fraction of thecost, can be used with equal or better performance than pure Mg. The seeminglysuperior alloy, AZ61 exhibits a coloumbic eciency close to 100%, at higher chargerates than pure Mg.

Det har i denne oppgaven blitt vist at inntektsgrunnlaget for plusskunder iNorge er forholdsvis lavt. Dette til tross for at Norges Vassdrags- og Energidirektorat(NVE) har foretatt flere dispensasjoner, samt kommet med forslag tiltariffering for å gjøre plusskundeordningen mer lønnsom og attraktiv. Blantbarrierene for plusskunder kan det nevnes; få leverandører av aktuell produksjonsteknologi,forholdsvis liten erfaring om plusshus blant norske byggefirmaog den mest dominerende barrieren, den økonomiske. Produksjonsteknologienesom er mest aktuelle for plusskunder, vind- og solkraft, har foreløpig forhøy kostnad per kWh til at ordningen er lønnsom.Det har i oppgaven blitt vist til studier utført av SINTEF og NVE somkonkluderer med en kostnad per kWh for kraftproduksjon fra solceller påmellom 3,33 NOK og 5 NOK. To småskala vindturbiner, i utgangspunktetgodt egnet til bygningsmontering grunnet rotordiameter under 2 meter,viste seg i et pilotprosjekt i Nederland å ha en produksjonskostnad på 22,91NOK/kWh og 14,48 NOK/kWh. Den største turbinen, med en rotordiameterpå 5 meter, kom best ut i testen med en produksjonskostnad på 2,03NOK/kWh. Et liknende prosjekt i Storbritannia konkluderte med at i 16av 26 testtilfeller var den målte ytelsen på bygningsmonterte vindturbiner40% lavere enn det som var oppgitt fra produsent. Dette avviket skyldes ihovedsak at virkningsgraden synker drastisk i urbane områder som følge avustabile vindforhold forårsaket av bygninger.NVEs forelåtte tariffering av plusskunder medfører at inntekter og besparelsertil en plusskunde i BKKs nett er estimert til å utgjøre 3352 NOKårlig. Med en oppgitt investeringskostnad på 200 000 NOK er det blitt vistat innvesteringen, gitt en forventet levetid på anlegget på 25 år, ikke vil blilønnsom med dagens kraftpriser og tariffsystem.I oppgaven har det blitt vist til tariffsystemene ”Erneuerbare-Energien Gesetz”(EEG) og ”Feed in Tariff Scheme” (FITs), henholdsvis i Tyskland ogStorbritannia. Det tyske tariffsystemet har bidratt sterkt til at Tyskland vedslutten av 2011 hadde 25 GW installert effekt fra solceller. I Storbritanniakan en plusskunde med et solcelleanlegg på 2,9 kWp forvente inntekter ogbesparelser opp mot 11 000 NOK årlig. I løpet av anleggets levetid kan detteutgjøre opp mot 280 000 NOK. Denne summen står i sterk kontrast til hva en norsk plusskunde per i dag kan forvente, som i løpet av levetiden til anleggeter estimert til å utgjøre om lag 87 000 NOK.Det har også i oppgaven blitt trukket frem at distribuert fornybar kraftproduksjonkan gi utfordringer knyttet til leveringskvalitet, spenningsstabilitetog personsikkerhet. Blant annet er vekselrettere, som er nødvendig for å omformelikespenning til vekselspenning, en kilde til harmoniske i kraftnettet.Et høyt innslag av vekselrettere i kraftnettet innebærer at anleggene for eksempelmå installerer filtre for å unngå at harmoniske sprer seg ut i nettet.Uønsket øydrift av distribuert kraftproduksjon kan i tillegg være en fare fornettselskapets ansatte ved vedlikehold i kraftnettet. Dette stiller også kravtil anleggets evne til å detektere øydrift og koble ut plusskunden. Det internasjonaleenergibyrået (IEA) har i en rapport konkludert med at risiko forpersonskade som følge av øydrift av solcelleanlegg hos plusskunde er 10^-9 årlig.Det har blitt diskutert at varierende innstråling på solcelleanlegg og ustabilevindforhold byr på utfordringer med spenningsregulering. Det har blitt trukketfrem at transient skydekke kan gi ramper i kraftproduksjonen opp mot15% i sekundet. Grunnet det høye innslaget av kraftproduksjon fra solcellerhar tyske myndigheter innført et nytt regulativ for vekselrettere. Regulativetsetter blant annet krav til en vekselretters effektfaktor, samt at en vekselretterskal ha støtte for frekvensbasert effektreduksjon ved frekvenser over 50,2 Hz.Det har blitt vist at et kundedisplay i kombinasjon med avanserte måle- ogstyringssystem (AMS) kan være en sentral kilde til informasjon for plusskunden.Displayet kan presentere forbruk og produksjonsdata i tillegg tilinformasjon om feilsituasjoner i kraftnettet eller plusskundens produksjonsanlegg.Det har i oppgaven blitt presentert et system for hjemmeautomasjon ikombinasjon med et kundedisplay levert av selskapet Control41. Dette systemetstøtter individuell laststyring i husholdningen og innebærer at plusskundensenergiforbruk i større grad kan tilpasses tidspunkt for kraftproduksjon.Eksempelvis kan en vaskemaskin settes til å starte på tidspunkter der plusskundenproduserer egen kraft. Dette innebærer at det aktuelle apparatetdrives med særdeles kortreist og klimavennlig kraft.