The doctoral dissertations of the former Helsinki University of Technology (TKK) and Aalto University Schools of Technology (CHEM, ELEC, ENG, SCI) published in electronic format are available in the electronic publications archive of Aalto University - Aaltodoc.

Aspects on Bioenergy as a Technical Measure to Reduce Energy Related Greenhouse Gas Emissions

Margareta Wihersaari

Dissertation for the degree of Doctor of Science in Technology to be presented with due permission of the Department of Mechanical Engineering for public examination and debate in Auditorium S2 (Otakaari 5) at Helsinki University of Technology (Espoo, Finland) on the 31st of May, 2005, at 12 o'clock noon.

Overview in PDF format (ISBN 951-38-6446-4)   [1184 KB]
VTT Publications 564, ISSN 1455-0849

Dissertation is also available in print (ISBN 951-38-6445-6)
Copyright © 2005 VTT Technical Research Centre of Finland
VTT Publications 564, ISSN 1235-0621


Greenhouse gas emission assessments of energy supply systems have traditionally included the CO2 emissions produced as the fuel is burned. A lot of models and calculations for evaluating greenhouse gas emission savings by using bioenergy have been introduced. The approaches often cover a major part or sometimes even the whole energy system. The biofuel production process itself is one piece that is normally covered very briefly or considered insignificant. Unfortunately, this means that the significance of some affecting factors might not have been estimated.

The object of the thesis was to study the greenhouse gas balances in connection with the harvesting and production of biofuels and, based on this, evaluate in what situations there is a need to re-evaluate the potentials of greenhouse gas emission savings when using bioenergy for substituting fossil fuels.

Different methodologies were used in the separate evaluations: the philosophy and methodology of industrial ecology was used to analyse the sustainability and material flows of the Finnish forest industry. A simple calculation model was developed for analysing the energy consumption and greenhouse gas emissions for biomass production chains, upgrading of biofuels and production of solid recovered fuels. Emission risks from long-time storage of biofuel and biodegradable material were evaluated as well as changes in forest soil carbon due to harvesting of forest residues.

The examination of the biofuel production chains showed that in a favourable situation as much as 97-98% of greenhouse gas emissions for a fossil fuel could be avoided by substituting it with a biofuel. On the other hand the investigation also pointed out that e.g. increasing fuel storage and upgrading activities for biofuels are likely to decrease this percentage remarkably. The main conclusion of the thesis was that the neutrality of greenhouse gas emissions when producing bioenergy should be re-evaluated. The author further suggests that tools and stimulants for keeping the greenhouse gas emission levels in fuel production chains as low as possible should be developed.

This thesis consists of an overview and of the following 6 publications:

  1. Korhonen, J., Wihersaari, M. and Savolainen, I. Industrial ecology of the Finnish forest industry. Ecological Economics 39 (2001), pp. 145-161. Elsevier Science Ltd.
  2. Wihersaari, M. Energy consumption and greenhouse gas emissions from biomass production chains. Energy Conversation Mgmt (1996), Nos 6-8, pp. 1217-1221. Elsevier Science Ltd.
  3. Wihersaari, M. Greenhouse gas emissions from final harvest fuel chip production in Finland. Biomass and Bioenergy 28 (2005), pp. 435-443. Elsevier Science Ltd.
  4. Wihersaari, M. Evaluation of greenhouse gas emission risks from storage of wood residue. Biomass and Bioenergy 28 (2005), pp. 444-453. Elsevier Science Ltd.
  5. Palosuo, T., Wihersaari, M. and Liski, J. Net greenhouse gas emissions due to energy use of forest residues – Impact of soil carbon balance. EFI Proceedings No. 39 (2001); Wood Biomass as an Energy Source Challenge in Europe. European Forest Institute, Joensuu. Pp. 115-130.
  6. Pipatti, R. and Wihersaari, M. 1998. Cost-effectiveness of alternative strategies in mitigating the greenhouse impact of waste management in three communities of different size. Mitigation and Adaptation Strategies for Global Change (1998), Vol. 2, No. 4, pp. 337-358. Kluwer Academic Publishers.

Keywords: greenhouse gases, emissions, energy supply systems, biofuels, bioenergy, biomass production, wood fuels, forest residues, municipal wastes, renewable energy sources

This publication is copyrighted. You may download, display and print it for your own personal use. Commercial use is prohibited.

© 2005 Helsinki University of Technology

Last update 2011-05-26