Uncertainty in the global energy market and negative environmental impacts associated with fossil fuels has led to renewed interest in alternative fuels. The scalability of new technologies and production pathways are critically being evaluated through economic feasibility studies and environmental impact assessments. This work investigated the conversion of agricultural wast, delactosed whey permeate (delac), with yeast fermentation for the generation of biofuel via hydrothermal liquefaction (HTL). The feasibility of the process was demonstrated at laboratory scale with data leveraged to validate systems models used to perform industrial-scale economic and environmental impact analyses. Results showed a minimum fuel selling point of $4.56 per gasoline gallon equivalent (CGE), a net energy ratio (NER), defined as energy required to process biofuel divided by energy in the biofuel produced, of 0.81 and greenhouse gas (GHG) emissions of 30.03 g CO2-eq MJ-1. High Production costs can be attributed to operational temperatures of HTL while the high lipid yields of the yeast counter these heating demands, resulting in a favorable NER. The operating conditions of both fermentation and HTL contributed to the majority of GHG emissions. Further discussion focuses on optimization of the process, on the metrics of TEA and LCA and the evaluation of the process, on the metrics of TEA and LCA, and the evaluation of the process through a sensitivity analysis that highlights areas for directed research to improve commercial feasibility.

Every day 493 tonnes of waste containing 67% of organic material is generated in the city of El Alto in Bolivia. The majority of the waste is disposed to a landfill that is expected to reach its maximum capacity by 2015. Therefore, new waste treatment methods need to be explored. The high content of organic material in waste makes biogas technologies a potential solution for waste treatment in El Alto. These technologies can generate a renewable energy source and organic fertilizer that can provide several benefits to the city. The objective of this study is to investigate the techno-economic feasibility of a small-scale biogas plant for treating organic market waste in the city of El Alto. To this end, a multi-criteria analysis was performed to identify a suitable technology. The garage-shaped digester was selected as the most appropriate technology for the conditions of El Alto. By implementing this technology, 1.8 GWh of electricity and 2,340 tonnes of organic fertilizer can be produced annually. Furthermore, an economic analysis of two scenarios was conducted. The Net Present Value (NPV), Internal Rate of Return, Payback time, Levelized Cost of Electricity (LCOE) and sensitivity analysis were evaluated. The biogas plant resulted economically viable in both cases. However, the LCOE estimated (0.17-0.26 USD/kWh) were very high in comparison to the LCOE from natural gas in Bolivia (0.026 USD/kWh). Regarding the sensitivity analysis, several parameters were evaluated from which the compost price was the most influential on changing the NPV. The study also included the estimation of the emission savings. A total of 900 tonnes of CO2/year could be avoided for producing electricity from biogas. Moreover, social benefits could also be generated such as new job opportunities. The use of a small-scale biogas plant for treating organic market waste in the city of El Alto is a cost-effective option. Though, it is fundamental that the government support the waste-to-biogas technologies by introducing economic mechanisms and promoting awareness to ensure the markets for both, biogas and organic fertilizer.

To meet the energy targets and improve the lack of power and higher prices in southern Sweden, the amount of electricity must increase, and alternative fuel sources be introduced. This thesis examines the techno-economic feasibility of offshore wind-hydrogen production in southern Sweden, depending on whether an onshore- or offshore hydrogen system is used, and how grid connection subsidies would affect this. New research and development regarding the subjects were analyzed and reviewed. A project that has currently applied for a permit in southern Sweden, Skåne Offshore Wind Park, was used as a case study where the information from the review and data from similar parks were used to determine the cost and production for the two different systems. The costs were then adjusted according to the three different subsidy scenarios: current with no subsidies, partial with sea cable and transformer costs removed, or a full subsidy scenario where only the internal grid cost remained to achieve feasible levelized costs for electricity and hydrogen based on a discount rate of 6% and a lifetime of 25 years. Finally, a sensitivity analysis was performed.   The results showed that market competitive electricity prices are only achieved with an onshore hydrogen system- and only if a full subsidy is introduced or if a best-case scenario is applied. In a worst-case scenario, no competitive electricity prices were achieved. For the offshore hydrogen system, the extra fuel system is too inefficient for electricity production. For hydrogen, prices were achieved within a reasonable price range of green hydrogen for all scenarios, where the onshore hydrogen system was 4% more advantageous. In a best-case scenario, competitive values ​​even against blue hydrogen were achieved for the offshore hydrogen systems and for the full subsidy onshore hydrogen system. For hydrogen, the offshore hydrogen system's hydrogen prices were competitive regardless of subsidies, however this system had the highest CAPEX and OPEX costs.   The results of the study underline the need for fixed conditions but also the necessity of introducing a full subsidy for the grid connection cost - or best-case scenario conditions - to encourage further offshore wind power development.

This thesis presents the potential of biogas production using food waste collected from the region of Kartamantul in Yogyakarta, Indonesia. Biogas can be used for cooking and generating electricity. The study compares two different end uses or markets for utilizing the biogas in the region. The daily food waste collected in the region of Kartamantul is 120 tonnes. This corresponds to a daily biogas production of 13 087 m3. Electricity generated from biogas can replace fossil-based coal electricity while cooking biogas can substitute the common fossil fuel liquefied Petroleum Gas (LPG). The price for selling one kWh of electricity to the state owned enterprise PLN is 16.5 USD cents. The price for selling one m3 of biogas for cooking is 38.5 USD cents, which is equivalent to the available price of LPG. The study finds that the avoided emission due to the substitution of fossil-based coal electricity and cooking LPG-gas is around 64 GgCO2-eq per year. Considering the economical results for a life span of 20 years in the first utilization option Biogas for Electricity gives a net present value (NPV) of 2 MUSD while for the utilization option Biogas for Cooking gives a net present value (NPV) of 5.82 MUSD. The breakeven for Biogas for Electricity is 13.8 USD cents per kWhe while for Biogas for Cooking is 25.5 USD cents per m3-biogas. The study concludes that it is feasible to invest in AD plant in the region of Kartamantul where both markets are profitable and environmentally friendly. / Denna avhandling visar potentialen för biogasproduktion med hjälp av matavfall som samlats från regionen Kartamantul i Yogyakarta, Indonesien. Biogas kan användas för matlagning och elproduktion. Studien jämför två olika slutanvändningar eller marknader för att utnyttja biogasen i regionen. Det dagliga matavfallet som samlas i regionen Kartamantul är 120 ton. Detta motsvarar en daglig biogasproduktion på 13 087 m3. Elektricitet som genereras från biogas kan ersätta fossilbaserad koldioxid, medan tillagning av biogas kan ersätta det gemensamma fossila bränslet flytande petroleumgas (LPG). Priset för att sälja en kWh el till det statligt ägda företaget PLN är 16,5 USD cent. Priset för att sälja en m3 biogas för matlagning är 38,5 USD cent, vilket motsvarar det tillgängliga priset på LPG. Studien konstaterar att den undvikna utsläppet på grund av substitutionen av fossilbaserad kolkraft och matlagning av gasol är cirka 64 GgCO2-ekv per år. Med tanke på de ekonomiska resultaten för en livslängd på 20 år i det första utnyttjandegradet ger Biogas for Electricity ett nettopåverkande värde (NPV) på 2 MUSD medan för utnyttjandegraden Biogas for Cooking ger ett nettoförskott (NPV) på 5,82 MUSD. Breakeven för biogas för el är 13,8 USD cent per kWhe medan för Biogas for Cooking är 25,5 USD cent per m3-biogas. Studien drar slutsatsen att det är möjligt att investera i AD-anläggningar i regionen Kartamantul där båda marknaderna är lönsamma och miljövänliga.

The combination of Biomass Energy with Carbon Capture and Storage (BECCS) can reduce the level of CO2 in the atmosphere. It is, therefore, seen as an interesting tool in the CO2 abatement portfolio. In a Swedish context, BECCS could contribute to the goal of CO2 neutrality by 2045. This thesis aims to investigate the application of BECCS in the district heating system of Stockholm region with a case study at the energy utility Fortum Värme. The focus of the study is the technical and economic feasibility of such an application. The applicability of Fortum Värme´s plants to implement carbon capture is investigated together with costs and technical implications on each applicable plant and the district heating system as a whole. Three plants are deemed feasible for carbon capture with a cost of about 45€/tonne of captured CO2 (not including transport or storage). A model for transport of CO2 to promising storage sites in Sweden, Norway, and Denmark is constructed for transport by pipeline and ship. Ship transport is estimated to be the most cost-efficient option in all scenarios. The total cost for BECCS is calculated at 70-100€/tonne depending on size of emissions and distance to storage locations. Furthermore, the total cost is calculated to decrease by 10-25% if some current promising technologies for carbon capture reach maturity, a market for transport services of CO2 evolves, and a number of actors are sharing the costs for storage.Calculated costs are on a similar price level as other CO2 abatement strategies such as CCS in industries, biogas, and biodiesel in the vehicle fleet. If the cost is applied directly to the heat price, without any subsidies, it would increase the price of heat by 14-21%.The major challenge of BECCS in combined heat and power production, compared to other studies based on power production, is the seasonality of heat demand. The capacity of the carbon capture system will be oversized during the summer, or undersized during the winter. This is an optimization challenge which has to be further studied.