| 1. |
- Magnusson, Mimmi, 1980-, et al.
(författare)
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Biogas from mechanical pulping industry : Potential improvement for increased biomass vehicle fuels
- 2012
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Ingår i: Proceedings of the 25th International Conference on Efficiency, Cost, Optimization and Simulation of Energy Conversion Systems and Processes, ECOS 2012. - 9788866553229 ; , s. 56-67
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Konferensbidrag (refereegranskat)abstract
- Biogas is a vehicle fuel of the first generation of biofuels with great potential for reducing the climate impact from the transport sector. Today biogas is mainly produced by digestion in Sweden and the total amounts to 1.4 TWhLHV/year (2010) of which about 0.6 TWhLHV is upgraded and used in the transport sector. Using industrial wastewater, e.g. from a pulp and paper mill, as substrate for production of biogas, the amount of renewable fuel to the transport sector could be increased. In the pulping industry, substantial amounts of organic matter are generated; this is commonly treated aerobically to reduce the chemical oxygen demand (COD) in the effluent streams before discharge to a recipient. Treating these effluent streams mainly anaerobically instead could contribute to the transport sector's energy supply. The aim of this study is to investigate the potential for using effluent streams from the Swedish mechanical pulp and paper industry to produce biogas. A typical Swedish mechanical pulp mill is considered for anaerobic treatment of the wastewaters. This type of pulp mill presently uses conventional methods for wastewater treatment to reduce COD, but converting most of this to anaerobic treatment would increase the amount of biogas produced. When considering this conversion in a larger context, supposing that anaerobic treatment would be applied to all Swedish mechanical pulp mills, which stand for about 30% of the total Swedish pulp production, it is shown that the production could amount to as much as 0.5 TWhLHV/year of biogas. This represents about one third of the biogas produced in Sweden today. The main conclusion of this study is that if anaerobic treatment of effluent streams from the pulping industry were introduced, the biogas production in Sweden could be significantly increased, thus moving one step further in reducing the transport sector's climate impact.
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| 2. |
- Magnusson, Mimmi, 1980-, et al.
(författare)
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Biogas potential in the Swedish pulp and paper industry
- 2012
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Ingår i: Proceedings of ICCE 2012. - 9781771360425 ; , s. 61-68
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Konferensbidrag (refereegranskat)abstract
- The European Union target of 10 % renewable fuels in the transport sector by 2020 is still far off, with 2.6% renewables on the EU level (2007) and 5.7% nationally in Sweden (2010). Biogas today accounts for a minor share of the renewable vehicle fuels in Sweden, but has the potential to increase. This study estimates the potential for producing biogas by anaerobic digestion as a part of the wastewater treatment in Swedish pulp and paper mills. The technology is mature and is used for example in municipal wastewater facilities but not as yet in the Swedish pulp and paper industry even though many of the effluent streams are well-suited for it. The results show that applying anaerobic wastewater treatment at Sweden’s pulp and paper mills may render as much as 1 TWhLHV/year, which would increase the present biogas production of 1.4 TWhLHV (2010) by 70%.
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| 3. |
- Magnusson, Mimmi, 1980-
(författare)
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Energy systems studied of biogas : Generation aspects of renewable vehicle fuels in the transport system
- 2012
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The transport sector is seen as particularly problematic when concerns about climate change and dependency on fossil energy are discussed. Because of this, bioenergy is strongly promoted for use in the transport sector, both on a European level and nationally in Sweden. Even though bioenergy is considered one of the key solutions, it is generally agreed that both supply- and demand-side measures will be needed to achieve a change to a more sustainable transport system. One of the reasons for this is the limited availability of biomass, especially agricultural feedstocks competing with food or feed production. Woody biomass, however more abundant, is also exposed to tough competition from other sectors. In this thesis, the role of biogas as a vehicle fuel in a future sustainable transport system is discussed together with the prerequisites needed to realise such a transport system. Biogas is a biofuel that could be produced in several different ways: by anaerobic digestion, which is a first-generation production route, by gasification, which is a second-generation process, and by catalytic reduction of carbon dioxide, a third-generation technology. The main focus in this thesis is on biogas produced by anaerobic digestion and the results show that there is a significant potential for an increase compared to today’s production. Biogas from anaerobic digestion, however, will only be able to cover a minor part of the demand in the Swedish transport sector. Considering biogas of the second and third generations, the potential for production is more uncertain in a mid-term future, mainly due to competition for feedstock, the possibility to produce other fuels by these processes, and the present immaturity of the technology. The limited potential for replacing fossil vehicle fuels, either by biogas or other renewable fuels, clearly shows the need for demand-side measures in the transport system as well. This thesis shows the importance of technical and non-technical means to decrease the demand for transport and to make the transport as efficient as possible. The results show that both energy-efficient vehicles and behavioural and infrastructural changes will be required. Policies and economic incentives set by governments and decision-making bodies have a prominent role to play, in order to bring about a shift to a more sustainable transport system, however, measures taken on individual level will also have a great impact to contribute to a more sustainable transport system.
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| 4. |
- Mohseni, Farzad, et al.
(författare)
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Biogas from renewable electricity : Increasing a climate neutral fuel supply
- 2012
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Ingår i: Applied Energy. - : Elsevier BV. - 0306-2619 .- 1872-9118. ; 90:1, s. 11-16
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Tidskriftsartikel (refereegranskat)abstract
- If considering the increased utilisation of renewable electricity during the last decade, it is realistic to assume that a significant part of future power production will originate from renewable sources. These are normally intermittent and would cause a fluctuating electricity production. A common suggestion for stabilising intermittent power in the grid is to produce hydrogen through water electrolysis thus storing the energy for later. It could work as an excellent load management tool to control the intermittency, due to its flexibility. In turn, hydrogen could be used as a fuel in transport if compressed or liquefied. However, since hydrogen is highly energy demanding to compress, and moreover, has relatively low energy content per volume it would be more beneficial to store the hydrogen chemically attached to carbon forming synthetic methane (i.e. biogas). This paper presents how biogas production from a given amount of biomass could be increased by addition of renewable electricity. Commonly biogas is produced through digestion of organic material. Recently also biomass gasification is gaining more attention and is under development. However, in both cases, a significant amount of carbon dioxide is produced as by-product which is subject for separation and disposal. To increase the biogas yield, the separated carbon dioxide (which is considered as climate neutral) could, instead of being seen as waste, be used as a component to produce additional methane through the well-known Sabatier reaction. In such process the carbon could act as hydrogen carrier of hydrogen originating from water electrolysis driven by renewable sources. In this study a base case scenario, describing biogas plants of typical sizes and efficiencies, is presented for both digestion and gasification. It is assessed that, if implementing the Sabatier process on gasification, the methane production would be increased by about 110%. For the digestion, the increase, including process improvements, would be about 74%. Hence, this method results in greatly increased biogas potential without the addition of new raw material to the process. Additionally, such model would present a great way to meet the transport sector's increasing demand for renewable fuels, while simultaneously reducing net emissions of carbon dioxide.
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