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Like many large cities, Johannesburg faces several sustainability challenges such as unsustainable use of natural resources, emissions contributing to environmental- and waste related problems. The city is a provincial transport centre, and the transport sector is responsible for a large share of the city’s energy demand and emissions. To approach several of these challenges simultaneously the City of Johannesburg considers the possibilities to use renewable, waste-based, fuel for public transport and has shown a great interest in how Sweden produce and use biogas.  In this study an early assessment of the potential, feasibility, economic costs and environmental performance of a waste-based biomethane solution in Johannesburg is performed, with the purpose to fuel a public transport bus fleet. This has been done by developing and using a multi-criteria analysis (MCA). The MCA consists of four categories: potential, feasibility, economic costs and environmental performance. These categories consist of 17 key areas with corresponding key questions and indicators with relating scales used for scoring the indicators. The indicators and scales help identify what information is necessary to collect for the assessment. Furthermore, an Excel tool and a questionnaire are provided to serve as a help when performing the assessment. The feasibility assessment is conducted both for the city as a whole as well as for individual feedstocks. Information for the studied case was gathered from a literature study and interviews in Johannesburg with local experts and potential stakeholders.  The identified feedstocks in Johannesburg are landfill gas, waste from a fruit and vegetable market, organic household waste, abattoir waste, waste from the food industry, waste management companies and sewage sludge from the wastewater treatment plants (WWTP). The identified biomass potential is 230,000 tonnes of dry matter/year, generating a total biomethane potential of 91,600,000 Nm3/year, which is enough to fuel almost 2700 buses. In the process of producing biogas, digestate is created. The digestate can be used as biofertilizer and recycle nutrients when used in agriculture. The complete biomass potential in Johannesburg was not identified meaning there is additional potential, from e.g. other food industries, than examined in this study.  Assuming that all feedstocks except for landfill gas and WWTP sludge are processed in one biogas plant, the investment cost for this biogas plant is 28 million USD and the total operation and maintenance cost is 1.4 million USD per year. The investment cost and yearly operating cost for the upgrading plant is 43 million USD and 2.4 million USD respectively. Finally, the distribution costs were calculated, including compression and investment in vessels. The investment and operational costs for compression is 7.4 million USD and 220,000 USD/year respectively. The investment cost for the vessels was calculated to 15 million USD and the operational costs of the distribution 16 million USD/year. Consideration should be given to the fact that the numbers used when calculating these costs comes with uncertainties. Most indicators in the feasibility assessment of the city as a whole were given the score Poor, but some indicators were scored Satisfactory or Good. The assessment of the individual feedstocks led to a ranking of the most to the least feasible feedstocks where the waste from the fruit and vegetable market and the municipal household waste are considered being in the top. This assessment also shows the feedstocks are in general quite suitable for biomethane production. The issue is the lack of economic and legislative support and strategies not working in favour of biomethane. These are areas that can be improved by the local or national government to give better conditions for production of biomethane in the future. Some examples of this are a proposed landfill tax or landfill ban as well as a closing of the landfills due to the lack of new land. This could all contribute to better conditions for biomethane solutions in the future. Main identified hinders are electricity generation from biogas as a competitor with biomethane, and a general lack of knowledge about biogas and biomethane, from the high-level decision makers to a workforce lacking skills about construction and operation of biogas plants.

Production of biogas through anaerobic digestion is one pathway to achieving the European Union (EU) goals of reducing greenhouse gas emissions, increasing the share of renewable energy, and improving energy efficiency. In this thesis, two different models (Anaerobic Digestion Model No. 1 and an artificial neural network) are used to simulate a full-scale co-digester in order to evaluate the feasibility of such models. This thesis also includes models of two systems to study the inclusion of microalgae in biogas plants and wastewater treatment plants. One of the studies is a life-cycle assessment in which replacement of the ley crop with microalgae is evaluated. The other study concerns the inclusion of microalgae in case studies of biological treatment in three wastewater treatment plants. Finally, the co-digestion between microalgae and sewage sludge has been simulated to evaluate the effect on biogas and methane yield. The results showed that Anaerobic Digestion Model No.1 and the artificial neural network are suitable for replicating the dynamics of a full-scale co-digestion plant. For the tested period, the artificial neural network showed a better fit for biogas and methane content than the Anaerobic Digestion Model No. 1. Simulations showed that co-digestion with microalgae tended to reduce biomethane production. However, this depended on the species and biodegradability of the microalgae. The results also showed that inclusion of microalgae could decrease carbon dioxide emissions in both types of plants and decrease the energy demand of the studied wastewater treatment plants. The extent of the decrease in the wastewater treatment plants depended on surface volume. In the biogas plant, the inclusion of microalgae led to a lower net energy ratio for the methane compared to when using ley crop silage. Both studies show that microalgae cultivation is best suited for use in summer in the northern climate.

Biofuels produced from forest residues are much discussed in a Swedish context, among other things due to concerns for climate change. However, the undertaking of climate performance calculations is not an exact science. To examine whether climate concerns may be met by biofuels produced from forest residues, a literature review was carried out, analysing studies across methodologies. The scope for the literature review was limited to climate performance calculations for biofuels produced from forest residues harvested in Sweden. Five articles have been chosen for presentation, whereof one was carried out according to ISO 14040:2006 methodology, two according to climate performance calculations as stipulated by RED, two according to cumulative radiative forcing (CRF) and one according to a bottom up model using data from demo plants in Sweden (one study covers both ISO and RED methodology). All five studies presented in this paper suggest that climate performance of biofuels produced from forest residue (harvested in Sweden) show significantly better climate performance than fossil fuels. The local, environmental effects as well as future potential for harvesting of forest residue were also explored. A synthesis report on local, environmental effects suggests that the local, environmental effects are small. Furthermore, it is concludes that the effects on SOC are minor. Lastly, it is suggested that there is potential of increased harvesting of forest residue in Sweden in the magnitude of 30 TWh. / Biobränslen producerade av skogsavfall diskuteras mycket i en svensk kontext. Eftersom beräkningar av klimatprestanda inte är en exakt vetenskap, utfördes en litteraturstudie för att undersöka utifall biobränslen producerade från skogsavfall kan uppfylla förväntad klimatprestanda. Litteraturstudien avgränsades till beräkningar av klimatprestanda för biobränslen producerade av svenskt skogsavfall. Fem artiklar valdes ut, varav en använde sig av ISO 14040:2006 metodologi, två utfördes enligt RED, två enligt strålningsberäkningar och slutligen en som använt sig av data från demo fabriker i Sverige. Alla fem studierna visar att biobränslen producerade från svenskt skogsavfall har signifikant bättre klimatprestanda i jämförelse med fossila bränslen. De lokala miljömässiga effekterna samt framtida potential undersöktes. En syntesrapport drog slutsatsen att de lokala miljömässiga effekterna var små. Vidare, drogs slutsatsen i en annan rapport att effekterna på kol i marken var små. Slutligen uppskattades den framtida öka potentialen av ett ökat uttag av skogsbränsle till ca 30TWh per år.

För att Sverige ska nå klimatmålet om noll nettoutsläpp av växthusgaser till år 2045 behöver bland annat mer biobränslen fasas in och fossila bränslen fasas ut och därför behövs större produktion och fler alternativ av biobränslen. Pyrolysolja är ett alternativ till biobränsle som har forskats på sedan 1970-talet men som först för några år sedan börjat produceras i större skala för användning till värmeproduktion. Först i år startades även en byggnation för produktion av pyrolysolja som ska uppgraderas till biodrivmedel av Pyrocell. Pyrolysoljan har annorlunda egenskaper och sammansättning mot andra biooljor och fossila oljor. Till exempel har pyrolysolja högt vatteninnehåll, hög viskositet och högt innehåll av syresatta komponenter vilket gör att pyrolysoljan har lågt värmevärde, är svårare att hantera och är ostabil. Karlstad Energi AB har påbörjat ett projekt för att utvärdera en integrerad pyrolysreaktor vid en befintlig kraftvärmepanna med målsättningen att i framtiden producera pyrolysolja. De är intresserade av att använda pyrolysoljan som bränsle i två av deras reservpannor för fjärrvärmeproduktion och för att få produktionen lönsam är de dessutom intresserade av att sälja pyrolysoljan som råvara till drivmedelsindustrin. Syftet med arbetet är att undersöka pyrolysoljans användbarhet i Karlstad Energis system utifrån pyrolysoljans egenskaper, åldring, förbränning och uppgradering till biodrivmedel samt jämföra pyrolysoljans egenskaper och förbränning med biobränslet de använder idag, bio100. Målen är att; (1) kartlägga och jämföra pyrolysoljans egenskaper med bio100 utifrån litteratur, (2) beräkna och bedöma viskositetsförändring samt varmhållnings och förvärmningstemperaturer av färsk och lagrad pyrolysolja utifrån litteratur, (3) beräkna förbränningsegenskaper och förbränningsprestanda vid en uttagen effekt på 30 MW i reservpannan genom simulering i Chemcad tillsammans med en uppbyggd värmeöverföringsmodell i Excel och (4) undersöka möjligheten att uppgradera pyrolysolja till biodrivmedel genom teoretisk beräkning av vätgasbehov och oljeutbyte. Pyrolysoljan undersöks med 25, 15 och 8 vikt % vatten och tillsats av 5 och 10 vikt % metanol och etanol för att stabilisera pyrolysoljan samt förbättra förbränningen. Resultaten visar på att en pyrolysolja med 8 % vatteninnehåll kan ha alltför hög viskositet för att kunna pumpas och förbrännas i rimliga varmhållnings- och förvärmningstemperaturer, medan 26 och 15 % klarar det med rimliga temperaturer, med och utan tillsats av alkohol. Vid förbränning med en uttagen effekt på 30 MW krävs ca 1,9-2,6 gånger så högt oljeflöde och ca 1,05-1,21 gånger så högt rökgasflöde för pyrolysoljorna mot bio100 (3250 kg/h respektive 42900 m3/h). Det innebär att anläggningen skulle kunna vara underdimensionerad för att få ut 30 MW vid förbränning av pyrolysolja där oljeflödet förmodligen är det begränsande flödet. Detta kräver ytterligare utredning av utrustningen. Luft-bränsle förhållandet för att uppnå 4 % syreöverskott är ca dubbelt så stort för bio100 mot pyrolysoljorna (16 mot 6,7-8,6 kg luft/kg olja). Utsläpp av stoft och NOx kan bli väldigt högt på grund av det höga ask- och kväveinnehållet och kommer förmodligen inte klara de framtida utsläppsbegränsningarna varav åtgärder kommer behövas. Verkningsgraden (baserat på det högre värmevärdet) för 8 % vatteninnehåll med 10 % etanol kommer upp i samma verkningsgrad som bio100 (91 %) mot 26 och 15 % vatteninnehåll som kommer upp i ca 84 respektive 88 %. Det teoretiskt beräknade vätgasbehovet och oljeutbytet ligger mellan ca 575-775 liter vätgas/kg pyrolysolja respektive ca 45-62 %. Överlag är tillsats av metanol det bättre alternativet för viskositeten men etanol är bättre vid förbränning och uppgradering till biodrivmedel. / For Sweden to reach the goal of zero net emissions of greenhouse gases by the year 2045, more use of biofuels and less use of fossil fuels is needed and for this we need higher production and more options of biofuels. One option is pyrolysis oil which has been in research since the 1970’s but was only recently introduced to large-scale heat production. Also, this year Pyrocell have started the construction of a pyrolysis plant where the pyrolysis oil is going to be upgraded to biofuels. The pyrolysis oil has different properties and composition compared to other biooils and fossil oils. For example, it has high water content, high viscosity and high content of oxygenated compounds which makes the oil more difficult to handle, unstable and gives the oil a low heating value. Karlstads Energi AB has started a project to evaluate an integrated pyrolysis reactor to one of their existing combined heat and power plants with the objective to produce pyrolysis oil in the future. They are interested in using the pyrolysis oil as a fuel in two of their reserve boilers for district heating production and to sell as raw material to the fuel industry. The object of this study is to investigate the possibility of using the pyrolysis oil at Karlstads Energi in the meaning of properties, aging, combustion and upgrading to biofuel and to compare the properties and combustion performance with the fuel they are using today, bio100. The goals are to; (1) map and compare the properties and composition of pyrolysis oil with bio100 from literature, (2) calculate and estimate changes of viscosity and storage- and atomization temperatures of fresh and stored pyrolysis oil using data from literature, (3) calculate combustion properties and combustion performance at 30 MW power outlet from the boiler through simulation in Chemcad and a heat transfer-model in Excel and (4) investigate the possibility to upgrade pyrolysis oil to biofuel through theoretical calculation of hydrogen consumption and biofuel yield. The pyrolysis oil is investigated with 25, 15 and 8 wt% water and addition of 5 and 10 wt% methanol and ethanol to stabilize the oil and to improve the combustion. The results shows that a pyrolysis oil with 8 wt% water could have too high viscosity to be able to be pumped and combusted in reasonable temperatures while 26 and 15 wt% water have lower viscosity and can be used in reasonable temperatures, both with and without addition of alcohol. At combustion with 30 MW power output the flow of pyrolysis oil and flue gases is 1,9-2,6 times and 1,05-1,21 times higher than bio100, respectively (3250 kg/h and 42900 m3/h, respectively for bio100). This means that the facility could be undersized to be able to get 30 MW power output with pyrolysis oil, where the oil flow probably is the limiting factor. This requires further investigation of the equipment. The air-fuel-ratio to receive 4% excess oxygen in the flue gases for the pyrolysis oils is about half of that of bio100 (6,7-8,6 compared to 16 kg air/kg oil, respectively). The emissions of dust and NOx are high for the pyrolysis oils because of high content of ash and nitrogen and will probably exceed the future limitations of which measures will be needed. The efficiency (based on higher heating value) for pyrolysis oil with 8 wt% water and 10 wt% ethanol can reach the same efficiency as bio100 (91%), while 26 and 15 wt% water content reach 84 and 88%, respectively. The theoretical hydrogen consumption and biofuel yield were calculated to 575-775 L hydrogen/kg pyrolysis oil and 45-62%, respectively. Overall, addition of methanol is a better choice for the viscosity, but ethanol performs better in combustion and upgrading to biofuels.

Diss. (sammanfattning) Umeå : Umeå universitet, 2005. / Härtill 4 uppsatser.

Diss. (sammanfattning) Luleå : Luleå tekniska universitet, 2007. / Härtill 7 uppsatser.

Det blir allt viktigare med fler hållbara och miljövänliga lösningar för att kunna ta itu med dagens miljökris och för att kunna ersätta de fossila bränslena. Pelletseldning är en lösning som anses vara koldioxid neutralt och går att elda året runt. För att pelleten ska vara lätthanterlig och tålig så är de b.la. viktigt med en bra bulkdensitet och hållfasthet. Där spelar kylning av pellets roll och därför skall detta examensarbete undersöka hur olika kylningsmetoder påverkar pelletsen kvalité.   Ett antal prover av pellets tillverkades på Karlstad universitetet med en pelletsmaskin under två olika labbsessioner. Tre av dessa prover kyldes sedan på olika effekt på en fläkt i en mindre kylanläggning. Två andra prover kyldes i en hink och utspridda i en stor låda/plåt. Dessa stod under natten och kyldes till omgivningstemperaturen. Efter att proverna hade kylts så gjordes olika kvalitétstester på varje kylt prov; bulkdensitet, hållfasthet, hårdhet, fukthalt och andel fabriksmul mättes. En analys av insamlad data gjordes, efter det så kunde en slutsats dras.   En fältundersökning gjordes även för att utröna hur olika pelletsföretag går tillväga med deras kylningsprocess och hur tekniken på deras kylning ser ut.   Den kylningsmetod från första sessionen som hade bäst resultat i alla kvalitétstester var pelletsen som kyldes naturligt och utspridda i en låda, med en bulkdensitet på 646 kg/m3 och en hållfasthet på 96,6% samt minimalt fabrikssmul. Pelletsen som kyldes på lägsta effekt på kylanläggningen visade också bra resultat på testerna. De mindre bra kylningsmetoderna var pellets som kyldes i hink under natten samt pellets som kyldes på maxeffekt på kylanläggningen. Från andra sessionen så fick pelletsen som kyldes med 30Hz bäst hållfasthet på 98,6%  men lägst bulkvikt på 693 kg/m3. Pelletsen som kyldes med max effekt fick sämre hållfasthet och lägst hårdhet. Högst bulkvikt på 737 kg/m3 fick det provet som var utspritt på en plåt och kyldes naturligt. Inget tydligt samband kunde ses mellan resultaten från de olika labsessionerna.

No description available.

Biogas is a renewable form of energy that can be produced by a various type of organic materials. In order to reduce the proportion of fossil fuel emissions bioenergy is seen as a future energy source that can be used for different purposes. This report studies biogas from gasification and the purpose has been to investigate the potential for increased biogas production from agriculture and forestry by doing a sociotechnical system study. The study is focusing on a restricted area outside of Uppsala, Sweden, and has been carried out in two parts. The first part consists of calculation of the biomass potential in the area. The second part investigates the social factors of the bioenergy system and interviews are used to study relevant actors in the area. Social barriers are crucial to the realization of technical potentials, and are therefore important to identify. The result shows that there are some areas that need further development to fulfil the bioenergy potential in the area. All farmers and foresters say that the market is the most important factor for the bioenergy future. The result shows that the reliance for politicians and energy companies need to be increased in all parts of the system. There is also a need for long-term political guidelines at a global and local level. The information and knowledge exchanges about bioenergy need to increase between all actors involved in the system. This implies for example farmers, foresters, researchers, politicians and energy companies. Among these, new networks and collaboration need to be developed. There is also a need to develop more commercially viable technologies throughout the system to promote the development of a future bioenergy system. The result however, shows a large interest in bioenergy from farmers and foresters and a willingness to invest in future bioenergy projects which creates an advantageous starting point for the bioenergy system development.