The use of microalgae culture to convert CO2 from power plant flue gases into biomass that are readily converted into biofuels offers a new frame of opportunities to enhance, compliment or replace fossil-fuel-use. Apart from being renewable, microalgae also have the capacity to utilise materials from a variety of wastewater and the ability to yield both liquid and gaseous biofuels. However, the processes of cultivation, incorporation of a production system for power plant waste flue gas use, algae harvesting, and oil extraction from the biomass have many challenges. Using SimaPro software, Life cycle Assessment (LCA) of the challenges limiting the microalgae (Chlorella vulgaris) biofuel production process was performed to study algae-based pathway for producing biofuels. Attention was paid to material use, energy consumed and the environmental burdens associated with the production processes. The goal was to determine the weak spots within the production system and identify changes in particular data-set that can lead to and lower material use, energy consumption and lower environmental impacts than the baseline microalgae biofuel production system. The analysis considered a hypothetical transesterification and Anaerobic Digestion (AD) transformation of algae-to- biofuel process. Life cycle Inventory (LCI) characterisation results of the baseline biodiesel (BD) transesterification scenario indicates that heating to get the biomass to 90% DWB accounts for 64% of the total input energy, while electrical energy and fertilizer obligations represents 19% and 16% respectively. Also, Life Cycle Impact Assessment (LCIA) results of the baseline BD production scenario show high proportional contribution of electricity and heat energy obligations for most impact categories considered relative to other resources. This is attributed to the concentration/drying requirement of algae biomass in order to ease downstream processes of lipid extraction and subsequent transesterification of extracted lipids into BD. Thus, four prospective alternative production scenarios were successfully characterised to evaluate the extent of their impact scenarios on the production system with regards to lowering material use, lower energy consumption and lower environmental burdens than the standard algae biofuel production system. A 55.3% reduction in mineral use obligation was evaluated as the most significant impact reduction due to the integration of 100% recycling of production harvest water for the AD production system. Recycling also saw water demand reduced from 3726 kg (freshwater).kgBD- 1 to 591kg (freshwater).kgBD- 1 after accounting for evaporative losses/biomass drying for the BD transesterification production process. Also, the use of wastewater/sea water as alternative growth media for the BD production system, indicated potential savings of: 4.2 MJ (11.8%) in electricity/heat obligation, 10.7% reductions for climate change impact, and 87% offset in mineral use requirement relative to the baseline production system. Likewise, LCIA characterisation comparison results comparing the baseline production scenarios with that of a set-up with co-product economic allocation consideration show very interesting outcomes. Indicating -12 MJ surplus (-33%) reductions for fossil fuels resource use impact category, 52.7% impact reductions for mineral use impact and 56.6% reductions for land use impact categories relative to the baseline BD production process model. These results show the importance of allocation consideration to LCA as a decision support tool. Overall, process improvements that are needed to optimise economic viability also improve the life cycle environmental impacts or sustainability of the production systems. Results obtained have been observed to agree reasonably with Monte Carlo sensitivity analysis, with the production scenario proposing the exploitation of wastewater/sea water to culture algae biomass offering the best result outcome. This study may have implications for additional resources such as production facility and its construction process, feedstock processing logistics and transport infrastructure which are excluded. Future LCA study will require extensive consideration of these additional resources such as: facility size and its construction, better engineering data for water transfer, combined heat and power plant efficiency estimates and the fate of long-term emissions such as organic nitrogen in the AD digestate. Conclusions were drawn and suggestions proffered for further study.

The use of microalgae culture to convert CO2 from power plant flue gases into biomass that are readily converted into biofuels offers a new frame of opportunities to enhance, compliment or replace fossil-fuel-use. Apart from being renewable, microalgae also have the capacity to utilise materials from a variety of wastewater and the ability to yield both liquid and gaseous biofuels. However, the processes of cultivation, incorporation of a production system for power plant waste flue gas use, algae harvesting, and oil extraction from the biomass have many challenges. Using SimaPro software, Life cycle Assessment (LCA) of the challenges limiting the microalgae (Chlorella vulgaris) biofuel production process was performed to study algae-based pathway for producing biofuels. Attention was paid to material use, energy consumed and the environmental burdens associated with the production processes. The goal was to determine the weak spots within the production system and identify changes in particular data-set that can lead to and lower material use, energy consumption and lower environmental impacts than the baseline microalgae biofuel production system. The analysis considered a hypothetical transesterification and Anaerobic Digestion (AD) transformation of algae-to- biofuel process. Life cycle Inventory (LCI) characterisation results of the baseline biodiesel (BD) transesterification scenario indicates that heating to get the biomass to 90% DWB accounts for 64% of the total input energy, while electrical energy and fertilizer obligations represents 19% and 16% respectively. Also, Life Cycle Impact Assessment (LCIA) results of the baseline BD production scenario show high proportional contribution of electricity and heat energy obligations for most impact categories considered relative to other resources. This is attributed to the concentration/drying requirement of algae biomass in order to ease downstream processes of lipid extraction and subsequent transesterification of extracted lipids into BD. Thus, four prospective alternative production scenarios were successfully characterised to evaluate the extent of their impact scenarios on the production system with regards to lowering material use, lower energy consumption and lower environmental burdens than the standard algae biofuel production system. A 55.3% reduction in mineral use obligation was evaluated as the most significant impact reduction due to the integration of 100% recycling of production harvest water for the AD production system. Recycling also saw water demand reduced from 3726 kg (freshwater).kgBD- 1 to 591kg (freshwater).kgBD- 1 after accounting for evaporative losses/biomass drying for the BD transesterification production process. Also, the use of wastewater/sea water as alternative growth media for the BD production system, indicated potential savings of: 4.2 MJ (11.8%) in electricity/heat obligation, 10.7% reductions for climate change impact, and 87% offset in mineral use requirement relative to the baseline production system. Likewise, LCIA characterisation comparison results comparing the baseline production scenarios with that of a set-up with co-product economic allocation consideration show very interesting outcomes. Indicating -12 MJ surplus (-33%) reductions for fossil fuels resource use impact category, 52.7% impact reductions for mineral use impact and 56.6% reductions for land use impact categories relative to the baseline BD production process model. These results show the importance of allocation consideration to LCA as a decision support tool. Overall, process improvements that are needed to optimise economic viability also improve the life cycle environmental impacts or sustainability of the production systems. Results obtained have been observed to agree reasonably with Monte Carlo sensitivity analysis, with the production scenario proposing the exploitation of wastewater/sea water to culture algae biomass offering the best result outcome. This study may have implications for additional resources such as production facility and its construction process, feedstock processing logistics and transport infrastructure which are excluded. Future LCA study will require extensive consideration of these additional resources such as: facility size and its construction, better engineering data for water transfer, combined heat and power plant efficiency estimates and the fate of long-term emissions such as organic nitrogen in the AD digestate. Conclusions were drawn and suggestions proffered for further study.

Biogas is of growing interest in Sweden, and a public inquiry suggested the government to set a goal of producing 10 TWh biogas in 2030 although only 2 TWh biogas was produced in Sweden in 2018 (Regeringskansliet, 2019) (Klackenberg, 2019). To achieve this optimistic goal and to meet the increased demand of biogas, new biogas production facilities needs to be built. The purpose of this report is to investigate the economic feasibility for the development of a biogas recovery process adjoined to an incineration facility in Sweden. The report first gives an overview of the largest incineration facilities in Sweden. The largest quantity of food waste was estimated in Gothenburg to be 56´744 WRQ SeU \eaU. For the economic feasibility, a conceptual facility was constructed with 169´000 ton residual waste per year of which 45´000 ton was food waste. A biogas process model was built in Excel where the biogas potential was calculated using characteristics for food waste. The annual production of liquid biogas was estimated to 43´970 MWK. The economic evaluation was based on the conceptual facility. In the baseline scenario the incomes for the process was the value of liquid biogas, 25,6 MSEK per year, a Gate-fee synergy of 5 MSEK per year and a Tax deduction synergy of 1 MSEK per year. The investment cost was estimated to 211,6 MSEK and the Operation & Maintenance cost was estimated to 6,3 MSEK per year. This resulted in an NPV of 69,5 MSEK and an IRR of 10,3% for the project, indicating a profitable investment. Three different scenarios were considered, apart from the baseline scenario, where the first excluded all synergies with the incineration facility, which generated an NPV of 2,3 MSEK. The second scenario only considered the minimal gate-fee synergy which gave an NPV of 37,8 MSEK. Finally, the third scenario where all synergies were included, and an additional investment grant was introduced gave the project an NPV of 111,8 MSEK. A sensitivity analysis was also conducted which showed that the input of food waste treated, weighted average cost of capital and potential grants had the biggest impact on the financial results. None of the results from the sensitivity analysis showed a negative NPV. / Intresset för biogas växer i Sverige och i en statlig utredning föreslogs regeringen att sätta upp ett mål att producera 10 TWh biogas 2030 (Regeringskansliet, 2019). Detta kan jämföras med 2018 då endast 2 TWh producerades (Klackenberg, 2019). För att uppnå detta optimistiska mål och för att möta den ökade efterfrågan på biogas behöver nya produktionsanläggningar byggas. Syftet med denna rapport är att undersöka de ekonomiska möjligheterna för utvecklingen av en biogasanläggning angränsad till en förbränningsanläggning i Sverige. Rapporten ger först en översikt över de största förbränningsanläggningarna som behandlar hushållsavfall i Sverige. Det uppskattades att den största mängden matavfall som går till förbränning i Sverige är i Göteborg där 56´744 ton matavfall förbränns per år. För att bestämma de ekonomiska förutsättningarna konstruerades en konceptuell anläggning som behandlar 169´000 ton restavfall per år varav 45 000 ton består av matavfall. En biogasprocess modellerades i Excel där den potentiella biogasen beräknades baserat på matavfallets karaktäristik. Slutligen uppskattades den årliga produktionen av flytande biogas till 43´970 MWh. Den ekonomiska utvärderingen baserades på den konceptuella anläggningen. I grund-scenariot bestod inkomsterna för av den flytande biogasen som motsvarade 25,6 MSEK per år, en ´gatefee´-synergi på 5 MSEK per år och en ´skatteavdrags´-synergi motsvarande 1 MSEK per år. Investeringskostnaden uppskattades till 211,6 MSEK och Operation & Maintenancekostnaderna uppskattades till 6,3 MSEK. Detta gav projektet ett nettonuvärde på 69,5 MSEK och en internränta på 10,3% vilket indikerar en lönsam investering. Vidare undersöktes även tre olika scenarier, utöver grund-scenariot, där det första utesluter alla synergier vilket gav ett nettonuvärde på 2,3 MSEK. Det andra scenariot beaktade endast den minimala ´gate-fee´-synergin vilket gav ett nettonuvärde på 37,8 MSEK. Det tredje scenariot inkluderade alla synergier samt ett investeringsbidrag vilket resulterade i ett nettonuvärde på 111,8 MSEK. En känslighetsanalys genomfördes också som visade att tillförseln av behandlat matavfall, kapitalkostnaden och potentiella investeringsbidrag hade den största påverkan på de finansiella resultaten. Inget av resultaten från känslighetsanalysen visade ett negativt nettonuvärde.

Curitiba is a city of two million inhabitants located in the South of Brazil. It is a pioneer in waste management in the country, and is famous for its programs promoting recycling and organic waste collection. The city is now willing to take waste management one step further by investigating new solutions to treat and recover energy from organic municipal solid waste. This report is the fruit of a collaboration between two departments of the municipality of Curitiba, four local universities, the Swedish environment protection agency and the Royal Institute of Technology – KTH. The purpose of this report is to assess the potential for the development of anaerobic digestion as a solution to treat the organic municipal solid waste generated in Curitiba. The report offers an overview of the current waste treatment and of the main sources of organic waste in Curitiba. The annual amount of organic waste generated in the city is estimated to 144,350 tons, of which 913 tons come from food markets supervised by SMAB, the secretary of food supply. Three different scenarios, corresponding to three ranges of waste sources, have been considered. In the first one, the organic wastes generated by one of the two public markets of Curitiba are treated on-site. In the second one, all the organic wastes from food markets, street markets and popular restaurants are treated together in a medium-scale anaerobic digester. In the third one, all the sources of organic municipal solid waste identified in Curitiba are considered, including residential, institutional and small commercial waste. The annual methane production is estimated to 5,400 m3, 86,000 m3 and 12,600,000 m3 respectively for the three scenarios. In the last two scenarios, the methane could be converted into electricity, resulting in an annual electricity production of 257 MWh and 37,600 MWh. The first scenario does not consider a post-treatment of the digestate remaining at the end of the digestion. Between 46 and 50 tons of digestate could be used as a liquid fertilizer on-site and the surplus could be sold. For the two other scenarios, the digestate would be dewatered and composted to be sold as a dry fertilizer. The dry fertilizer production is estimated to 386 tons and 63,000 tons respectively every year. Each of the scenario considered would be financially viable, with a discounted payback period varying from 8 months for the small-scale scenario, to over 15 years for the second scenario. The third scenario would be the most lucrative, with a net present value of about 150 million reals. / Curitiba i Södra Brasilien är en stad med två miljoner invånare som har positionerat sig som pionjär inom avfallshantering. Staden är känd i landet med sin främjande strategi för återvinning och organisk avfallshantering. Curitiba planerar att undersöka och experimentera med nya metoder för behandling av avfall kombinerad med energiåtervinning från kommunalt organiskt avfall. Denna rapport är resultat av ett samarbete mellan två avdelningar inom Curitibas kommun, fyra lokala universitet, Sveriges miljöskyddsmyndighet och den Kungliga Tekniska Högskolan. Syftet med denna rapport är att utvärdera den potentialen som den anaeroba nedbrytningen har som medel för behandling av det kommunala fasta avfallet som genereras i Curitiba. Rapporten går även igenom hur avfallshanteringen ser ut i staden i dagsläget samt sammanfattar de största källorna för organiskt avfall i Curitiba. Den årliga mängden organiskt avfall som produceras i staden uppskattas till 144 350 ton, varav 913 ton kommer från livsmedelsaktiviteter som övervakas av det brasilianska livsmedelsverket SMAB. Tre olika scenarier representeras i denna rapport och omfattar tre områden av avfallskällor. I det första scenariot behandlas det organiska avfallet som genereras av en av de två köpmarknaderna i Staden direkt på plats. I det andra behandlas allt organiskt avfall från livsmedelsmarknader, gatumarknader och populära restauranger tillsammans i en medelstor anaerob kokare. I det tredje beaktas alla källor till organiskt kommunalt avfall som identifierats i Curitiba, inklusive bostads-, institutionellt och litet kommersiellt avfall. Den årliga metanproduktionen uppskattas till 5 400 m3, 86 000 m3 respektive 12 600 000 m3 för de tre scenarierna. I det andra och tredje scenariot kunde metan omvandlas till el, vilket resulterade i en årlig elproduktion på 257 MWh respektive 37 600 MWh. I det första scenariot anses inte en efterbehandling av digestatet kvar vid slutet av matsmältningen. Mellan 46 och 50 ton digestat kan användas som flytande gödselmedel på plats och överskottet kan säljas. För de två andra scenarierna skulle digestatet avvattnas och komposteras för att senare säljas som torr gödsel vars produktion beräknas uppgå till 386 ton respektive 63 000 ton varje år. Alla tre scenario som presenteras i denna rapport anses vara ekonomiskt genomförbara med en diskonterad återbetalningstid som varierar mellan 8 månader för det första scenariot till över 15 år för det andra scenariot. Det tredje scenariot anses vara det mest lukrativa med ett nuvärde på ca 150 miljoner realer.