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- Börjesson, Pål
(författare)
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Biomass in a Sustainable Energy System
- 1998
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The increased use of biomass for energy is as a key strategy in reducing carbon dioxide (CO2) emission, which represents the largest anthropogenic contribution to the greenhouse effect. In this thesis, aspects of an increase in the utilisation of biomass in the Swedish energy system are treated. Modern bioenergy systems should be based on high energy and land-use efficiency since biomass resources and productive land are limited. The energy input, including transportation, per unit biomass produced is about 4-5% for logging residues, straw and short-rotation forest (Salix). Salix has the highest net energy yield per hectare among the various energy crops cultivated in Sweden (Article I). The CO2 emissions from the production and transportation of logging residues, straw and Salix, are equivalent to 2-3% of those from a complete fuel-cycle for coal (Article II). Substituting biomass for fossil fuels in electricity and heat production is, in general, less costly and leads to a greater CO2 reduction per unit biomass than substituting biomass-derived transportation fuels for petrol or diesel. Transportation fuels produced from cellulosic biomass provide larger and less expensive CO2-emission reductions than transportation fuels from annual crops (Article III). Biomass has the potential to become the dominating energy source in Sweden. The current use of about 80 TWh/yr could increase to about 200 TWh/yr, taking into account estimated production conditions around 2015. Swedish CO2 emissions could be reduced by about 50% from the present level if fossil fuels are replaced and the energy demand is unchanged (Articles III and IV). There is a good balance between potential regional production and utilisation of biomass in Sweden. Future biomass transportation distances need not be longer than, on average, about 40 km. About 22 TWh electricity could be produced annually from biomass in large district heating systems by cogeneration (Article IV). Cultivation of Salix and energy grass could be utilised to reduce the negative environmental impact of current agricultural practices, such as the emission of greenhouse gases, nutrient leaching, decreased soil fertility and erosion, and for the treatment of municipal waste water and sludge, leading to increased recirculation of nutrients (Article V). About 20 TWh biomass could theoretically be produced per year at an average cost of less than 50% of current production cost, if the economic value of these local environmental benefits is included (Article VI).
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| 2. |
- Börjesson, Pål, et al.
(författare)
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Biomass Transportation
- 1996
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Ingår i: Renewable Energy. - : Elsevier BV. - 0960-1481. ; 9:1-4, s. 1033-1036, s. 1033-1036
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Tidskriftsartikel (refereegranskat)abstract
- Extensive utilisation of logging residues, straw, and energy crops will lead to short transportation distances and thus low transportation costs. The average distance of transportation of biomass to a large-scale conversion plant, suitable for electricity or methanol production using 300 000 dry tonne biomass yearly, will be about 30 km in Sweden, if the conversion plant is located at the centre of the biomass production area. The estimated Swedish biomass potential of 430 PJ/yr is based on production conditions around 2015, assuming that 30% of the available arable land is used for energy crop production. With present production conditions, resulting in a biomass potential of 220 PJ/yr, the transportation distance is about 42 km. The cost of transporting biomass 30-42 km will be equivalent to 20-25% of the total biomass cost. The total energy efficiency of biomass production and transportation will be 95-97%, where the energy losses from transportation are about 20%. Biomass transportation will contribute less than 10% to the total NOx, CO, and HC emissions from biomass production, transportation, and conversion.
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| 4. |
- Börjesson, Pål
(författare)
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Emissions of CO2 from Biomass Production and Transportation in Agriculture and Forestry
- 1995
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Ingår i: Energy Conversion and Management. - : Elsevier BV. - 0196-8904. ; 37:6-8, s. 1235-1240
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Tidskriftsartikel (refereegranskat)abstract
- Net CO2 emissions have been calculated for the production and transportation of biomass in Swedish agriculture and forestry, using fossil-fuel-based energy inputs. An analysis of how a transition from a fossil-fuel-based energy system to a CO2-neutral biomass-based system would affect the energy efficiency in biomass production and transportation, has also been carried out. Production and transportation of short-rotation forest (Salix), straw, and logging residues exhibited the lowest CO2 emissions per unit energy delivered, equal to about 50% of those from perennial ley crops and 10 to 30% of those from annual food crops. Compared with CO2 emissions from a complete fuel-cycle for coal, net emissions of CO2 from Salix production, including transportation 50 km by truck, are 35 to 40 times lower when fossil-fuel inputs are used. Future increases in yield and technological development are estimated to reduce net CO2 emissions from biomass production by 30 to 50% in a fossil-fuel-based energy system around the year 2015. A transition from a fossil-fuel-based, to a CO2-neutral biomass-based energy system around 2015, is estimated to increase the energy input in biomass production and transportation by about 40% and 20%, respectively, resulting in a decreased net energy output from biomass production (including transportation) by about 4%.
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| 7. |
- Börjesson, Pål
(författare)
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Energy Analysis of Biomass Production and Transportation
- 1996
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Ingår i: Biomass & Bioenergy. - : Elsevier BV. - 1873-2909 .- 0961-9534. ; 11:4, s. 305-318
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Tidskriftsartikel (refereegranskat)abstract
- Energy efficiency in the production and transportation of different kinds of biomass in Sweden has been analysed, as well as the change in energy efficiency in a transition from fossil-fuel-based to biomass-based systems. Net energy yields under current production conditions were found to be highest for short-rotation forest (Salix) and sugar beet (about 160 to 170 GJ ha-1 year-1), followed by ley crops (110 to 140 GJ ha-1 year-1), and rape, wheat, and potatoes (50 to 90 GJ ha-1 year-1). The energy input per unit biomass produced is lowest for straw, logging residues and Salix, equal to 4 to 5% of the energy output. Corresponding figures for perennial ley crops are 7 to 10% and for annual crops 15 to 35%. Salix chips can be transported by truck about 250 km before the transportation energ is equal to the production energy. Corresponding distances for tractor, train and boat (coastal shipping) are about 100 km, 500 km and 1000 km, respectively. It is estimated that future increases in yield and technological development will almost double net energy yields for dedicated energy crops within the next two decades. A transition from a fossil-fuel-based energy system to a CO2-neutral biomass-based system around the year 2015 is estimated to increase the energy input in biomass production and transportation by about 30 to 45%, resulting in a decreased net energy output of about 4%.
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| 11. |
- Börjesson, Pål, et al.
(författare)
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Future Production and Utilisation of Biomass in Sweden: Potentials and CO2 Mitigation
- 1997
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Ingår i: Biomass & Bioenergy. - 1873-2909 .- 0961-9534. ; 13:6, s. 399-412
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Tidskriftsartikel (refereegranskat)abstract
- Swedish biomass production potential could be increased significantly if new production methods, such as optimised fertilisation, were to be used. Optimised fertilisation on 25% of Swedish forest land and the use of stem wood could almost double the biomass potential from forestry compared with no fertilisation, as both logging residues and large quantities of excess stem wood not needed for industrial purposes could be used for energy purposes. Together with energy crops and straw from agriculture, the total Swedish biomass potential would be about 230 TWh/yr or half the current Swedish energy supply if the demand for stem wood for building and industrial purposes were the same as today. The new production methods are assumed not to cause any significant negative impact on the local environment. The cost of utilising stem wood produced with optimised fertilisation for energy purposes has not been analysed and needs further investigation. Besides replacing fossil fuels and, thus, reducing current Swedish CO2 emissions by about 65%, this amount of biomass is enough to produce electricity equivalent to 20% of current power production. Biomass-based electricity is produced preferably through co-generation using district heating systems in densely populated regions, and pulp industries in forest regions. Alcohols for transportation and stand-alone power production are preferably produced in less densely populated regions with excess biomass. A high intensity in biomass production would reduce biomass transportation demands. There are uncertainties regarding the future demand for stem wood for building and industrial purposes, the amount of arable land available for energy crop production and future yields. These factors will influence Swedish biomass potential and earlier estimates of the potential vary from 15 to 125 TWh/yr.
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| 21. |
- Börjesson, Pål, et al.
(författare)
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Regional Production and Utilisation of Biomass in Sweden
- 1996
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Ingår i: Energy. - : Elsevier BV. - 1873-6785 .- 0360-5442. ; 21:9, s. 747-764
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Tidskriftsartikel (refereegranskat)abstract
- Regional production and utilization of biomass in Sweden is analysed, considering the potential of replacing fossil fuels and producing new electricity. Extensive utilization of biomass will decrease biomass-transportation distances. The average distance for biomass transportation to a large-scale conversion plant suitable for electricity or methanol production will be 30–42 km when the conversion plant is located in the centre of the biomass production area. The total energy efficiency of biomass production and transportation will be 95–97% and the emissions of air pollutants will be small. In areas where energy crops from agriculture constitute the main part of the biomass, the transportation distance will be two to three times shorter than in areas where logging residues from forestry dominate. When present Swedish fossil-fuel use for heat and electricity production is replaced, more than 75% of the biomass required can be produced locally within the county. The average transportation distance of the remaining part will be between 130 and 240 km, increasing the cost of this biomass by 15–20%. Increased use of biomass by 430 PJ/yr, the estimated potential for increased utilization of energy crops, logging residues and straw, will lead to an excess of about 200 PJ/yr biomass after fossil fuels for electricity and heat production have been replaced. This biomass could be used for methanol or electricity production. The production of biomass-based methanol will lead to a low demand for transportation, as the methanol produced from local biomass can mainly be used locally to replace petrol and diesel. If the biomass is used for electricity production, however, the need for transportation will increase if the electricity is cogenerated in district heating systems, as such systems are usually located in densely populated areas with a deficit of biomass. About 60% of the biomass used for cogenerated electricity must be transported, on average, 230 km. Changing transportation mode when transporting biomass over large distances, compared with short distances, however, will lead to rather low specific transportation costs and environmental impact, as well as high energy efficiency. Replacing fossil fuels with biomass for heat and electricity production is typically less costly and leads to a greater reduction in CO2 emission than substituting biomass for petrol and diesel used in vehicles. Also, cogeneration of electricity and heat is less costly and more energy efficient than separate electricity and heat production.
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| 22. |
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| 23. |
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| 24. |
- Gustavsson, Leif, et al.
(författare)
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Biomass Utilisation and Transportation Demands
- 1996
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Ingår i: Renewable Energy. - : Elsevier BV. - 0960-1481. ; 9:1-4, s. 1037-1040
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Tidskriftsartikel (refereegranskat)abstract
- The need for biomass transportation depends on the balance between locally produced biomass and the local demand for fuel. In Sweden, more than 80% of the biomass assumed to be required to replace fossil fuels for the production of electricity and heat can be produced locally within each county, if biomass is extensively utilised. The average transportation distance of the remaining 20% will be between 100 and 200 km, which increases the cost of this biomass by 15–20%. Considering a yearly biomass potential of 430 PJ, based on estimated biomass production conditions around 2015, 190 PJ/yr excess biomass will remain after fossil fuels for electricity and heat production have been replaced. This biomass can be converted to methanol to replace petrol and diesel, or can be used in new electricity production plants. The production of biomass-based methanol will not lead to a high demand for transportation, as the methanol produced from local biomass and can mainly be used locally. Biomass used for electricity production will increase the need for transportation if electricity is cogenerated in district heating systems, as such systems are usually located in densely populated areas with a deficit of biomass.
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| 25. |
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| 26. |
- Gustavsson, Leif, et al.
(författare)
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Mitigation Costs for Bioenergy Systems and Natural Gas Systems with Decarbonization
- 1997
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Ingår i: Energy Policy. - 1873-6777. ; 26:9, s. 699-713
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Tidskriftsartikel (refereegranskat)abstract
- In Sweden today, power production with bioenergy systems is more costly than with fossil energy systems. New technology under development, such as integrated gasification and combined cycle technology (IGCC), and reduced biomass costs would improve the competitiveness of bioenergy systems. The CO2 mitigation costs are lower for biomass systems using IGCC technology than for natural gas systems using decarbonization. Considering the temporary reduced greenhouse gases from the soil when short-rotation forest (Salix) replaces annual food crops on mineral soils, the CO2 mitigation costs could be reduced further by about 10% for bioenergy systems. The cost of Salix can be reduced in the future by about 30% because of improvements in plant breeding and cultivation methods, and even more if Salix plantations are used for the treatment of municipal waste water. This would further improve the competitiveness of bioenergy systems. Several data used in the cost calculations are uncertain, especially regarding new technologies such as IGCC, decarbonization, and waste water treatment in Salix plantations, and will vary with local conditions. The results are, however, most sensitive to changes in the fuel costs and particularly so in the case of natural gas systems.
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| 27. |
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| 28. |
- Gustavsson, Leif, et al.
(författare)
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Reducing CO2 Emissions by Substituting Biomass for Fossil Fuel
- 1995
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Ingår i: Energy. - 1873-6785. ; 20:11, s. 1097-1113
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Tidskriftsartikel (refereegranskat)abstract
- Replacing fossil fuels with sustainably-produced biomass will reduce the net flow of CO2 to the atmosphere. We express the efficiency of this substitution in reduced emissions per unit of used land or biomass and in costs of the substitution per tonne of C. The substitution costs are calculated as the cost difference between continued use of fossil fuels at current prices and the use of biomass, assuming that the biomass technologies are implemented when reinvestments in existing technologies are required. Energy inputs into biomass production and conversion are biomass-based, resulting in a CO2-neutral fuel cycle, while CO2 emissions from fossil fuels are estimated for the complete fuel cycles. Substituting biomass for fossil fuels in electricity and heat production is, in general, less costly and provides larger CO2 reduction per unit of biomass than substituting biomass for gasoline or diesel used in vehicles. For transportation, methanol or ethanol produced from short-rotation forests or logging residues provide larger CO2-emission reductions than rape methyl ester from rape seed, biogas from lucerne (alfalfa), or ethanol from wheat. Of these, methanol has the lowest emission-reduction costs. Increasing biomass used by 125 TWh/yr, the estimated potential for increased utilization of logging residues, straw and energy crops, would eliminate more than one-half of the Swedish CO2 emissions from fossil fuels of 15 Mtonnes C in 1992.
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| 29. |
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