

@mastersthesis {6707,
	title = {Rational bioenergy utilisation in energy systems and impacts on carbon dioxide emissions},
	year = {2003},
	note = {C815639},
	school = {Kungliga Tekniska Hogskolan (Sweden)},
	type = {phdPh.{D}.},
	address = {Ann Arbor},
	abstract = {The increased concentration of greenhouse gases in the atmosphere, in particular CO2 , is changing the Earth{\textquoteright}s climate. According to the Kyoto protocol, where the international community agreed on binding emission targets, developed countries are committed to reduce their greenhouse gas emissions. The increased use of biomass in energy systems is an important strategy to reduce CO 2 emissions. The purpose of this thesis has been to analyse the opportunities for Sweden to further reduce CO2 emissions in the energy system, by rationally utilising woody biomass energy. The characteristics of current commercially operating biofuel-based CHP plants in Sweden are surveyed and systematically presented. A consistent and transparent comprehensive reference base for system comparisons is given. Furthermore, the fuel effectiveness and contribution to CO 2 reduction is calculated. The governmental subsidies of the CHP plants{\textquoteright} investment, expressed as cost of specific CO2 reduction, appears to be low. The competitiveness of biomass-fuelled energy production in relation to fossil-based production with carbon capture is analysed, showing that the biomass-fuelled systems provide a competitive option, in terms of cost of electricity and efficiencies. The remaining Swedish woody biofuel potential of at least 100 PJ/yr is principally available in regions with a biomass surplus. Transportation is therefore required to enable its utilisation in a further national and international market. Refining the biofuel feedstock to pellets, or even further refining to motor fuels (DME, methanol or ethanol) or power, could facilitate this transport. Different options for fuel refining are studied and compared. The entire fuel chain, from fuel feedstock to end users, is considered and CO 2 emissions are quantified. Substituting fuel pellets for coal appears to be the most cost-effective alternative and shows the largest CO2 reduction per energy unit biofuel. Motor fuels appear more costly and give about half the CO2 reduction. Transportation of the upgraded biofuel pellets is highly feasible from CO2 emissions point of view and does not constitute a hindrance for further utilisation, i.e. the pellets can be transported over long distances efficiently with only limited emissions of CO2 . Bioenergy utilisation has additional features for environmental improvement, apart from the CO2 aspect. Waste heat from biofuel-based CHP can be cost-effectively used in conjunction with sewage treatment. The incoming sewage water to the nitrification process can be preheated with the waste heat, and thereby substantially enhance the nitrification and the reduction of ammonium nitrogen during the winter season.},
	keywords = {0768:Environmental science, 0775:Environmental engineering, 0791:Energy, Applied sciences, Bioenergy, Carbon dioxide, Energy, Energy systems, Environmental engineering, Environmental science, Ethanol, Health and environmental sciences, Heat and power plants},
	url = {http://search.proquest.com/docview/305229807?accountid=14270},
	author = {Wahlund, Bertil}
}
