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- Berndes, Göran, 1966, et al.
(författare)
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Bioenergy and land use change-state of the art
- 2013
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Ingår i: Wiley Interdisciplinary Reviews: Energy and Environment. - : Wiley. - 2041-8396 .- 2041-840X. ; 2:3, s. 282-303
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Forskningsöversikt (refereegranskat)abstract
- Bioenergy projects can lead to direct and indirect land use change (LUC), which can substantially affect greenhouse gas balances with both beneficial and adverse outcomes for bioenergy's contribution to climate change mitigation. The causes behind LUC are multiple, complex, interlinked, and change over time. This makes quantification uncertain and sensitive to many factors that can develop in different directions-including land use productivity, trade patterns, prices and elasticities, and use of by-products associated with biofuels production. Quantifications reported so far vary substantially and do not support the ranking of bioenergy options with regard to LUC and associated emissions. There are however several options for mitigating these emissions, which can be implemented despite the uncertainties. Long-rotation forest management is associated with carbon emissions and sequestration that are not in temporal balance with each other and this leads to mitigation trade-offs between biomass extraction for energy use and the alternative to leave the biomass in the forest. Bioenergy's contribution to climate change mitigation needs to reflect a balance between near-term targets and the long-term objective to hold the increase in global temperature below 2 degrees C (Copenhagen Accord). Although emissions from LUC can be significant in some circumstances, the reality of such emissions is not sufficient reason to exclude bioenergy from the list of worthwhile technologies for climate changemitigation. Policy measures to minimize the negative impacts of LUC should be based on a holistic perspective recognizing the multiple drivers and effects of LUC.
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| 2. |
- Egnell, Gustaf
(författare)
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Options for increasing biomass output from long-rotation forestry
- 2013
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Ingår i: Wiley Interdisciplinary Reviews Energy and Environment. - : Wiley. - 2041-8396 .- 2041-840X. ; 2, s. 465-472
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Tidskriftsartikel (refereegranskat)abstract
- Forests managed by long-rotation forestry already play an important role as a source for renewable biomass and energy. The biomass output from these forests may be increased through higher harvest levels, but to be sustainable over time, harvest levels cannot exceed forest growth. A large proportion of the tree biomass (tops, foliage, branches, stumps, and small and unmerchantable trees) is left on the logging site in conventional stemwood harvest, representing a considerable amount of available biomass. The realizable biomass potential is lower, due to environmental and techno-economic constraints. If more technically adapted, efficient, and environmentally friendly biomass harvest and transport systems are developed, the realized biomass potential can be considerably increased. By complementing current stemwood harvesting technologies with systems that include logging residues, stumps, and small trees, a larger proportion of the potential will be available. In a longer term, increased forest growth can raise the biomass output. Many silvicultural treatments are available, including improved site preparation, vegetation control, insect control, browser control, genetically improved seedlings, fast growing tree species, fertilization, irrigation, denser stands, and so on. Inexpensive silvicultural measures that can be applied on large areas at a fast rate, such as using genetically improved seedling stock, have the highest potential to increase total forest production. Because of the long-rotation periods, it will take decades to make a difference in forest production and thereby in the biomass output potential. In addition, a more efficient use of biomass in both forest and energy industries and in biorefineries of the future holds potential. © 2012 John Wiley & Sons, Ltd.
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| 3. |
- Xiros, Charilaos, 1973, et al.
(författare)
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Hydrolysis and fermentation for cellulosic ethanol production
- 2013
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Ingår i: Wiley Interdisciplinary Reviews. - : Wiley. - 2041-8396 .- 2041-840X. ; 2:6, s. 633-654
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Tidskriftsartikel (refereegranskat)abstract
- Second-generation bioethanol produced from various lignocellulosic materials, such as wood, agricultural, or forest residues, has the potential to be a valuable substitute for, or a complement to, gasoline. At least three major factors—rapidly increasing atmospheric CO2 levels, dwindling fossil fuel reserves, and their rising costs—suggest that we now need to accelerate research plans to make greater use of plant-based biomass for energy production and as a chemical feedstock as part of a sustainable energy economy. Optimizing the production of bioethanol to be competitive with petrochemical fuels is the main challenge for the underlying process development. The exhaustive research on enzyme technology during the latest years, resulting in significant advances in the field, show the importance of the enzymatic hydrolysis for a profitable ethanol production process. On the other hand, the persisting challenges in biomass pretreatment, which are the initial steps in most process designs, show the remarkable recalcitrance of the lignocellulosic materials to biological degradation. The recent scientific trends show toward an integrated overall bioconversion process in which fermentation technology and genetic engineering of ethanologenic microorganisms aim not only at maximizing yields and productivities but also at widening the range of fermentation products and applications.
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