At present governments aim to increase the share of renewable energy in the
European Union as an attempt to reduce the emissions of green house gases.
One approach is to replace some of the non-renewable power generation
methods, with biomass based combined heat and power generation
technologies.
The main objective of this study has been to investigate the state-of-the-
art in the area of small-scale biomass based combined heat and power
generation. Other aims have been to identify proper biomass based CHP
technologies for the county of Norrbotten and to make a pre-study of such a
plant located in the small community Harads.
The technologies investigated were the Organic Rankine Cycle (ORC), steam
engine, gas engine and externally fired gas turbine (EFGT). An economic
comparison shows that no one of the considered technologies is economically
viable at present Swedish electric prices and green electric certificates.
In order to reach profitability the green electricity certificates or the
electricity prices must increase with at least 35 ?/MWhel. Still if the
problem of fouling and corrosion in the externally fired gas turbines heat
exchanger is solved in a sufficient way, this technology shows potential for
the future due the high electrical efficiency and resulting low cost of
electricity. This is also true for the gas engine, which has similar
problems with the dirty gas, yet this technology might be more suitable in
power ranges higher than 5 MWth.
Regarding the Harads plant, a 2 MWth Organic Rankine Cycle was assessed to
be the most suitable technology. Still, calculations showed that the
electricity share will be unprofitable, but the full-plant will be
economically viable due to a high return from the heat sales. Furthermore a
sensitivity analys...
