Worldwide use of biomass in power generation and combined beat and power schemes

Biomass is a truly renewable, sustainable source of energy; in its firewood form, at least, it has always been humanity's primary fuel. Nevertheless, it is only in the very recent past that it has been regarded as a viable substitute in power generation for the fossil fuels that have caused most of the world's environmental pollution problems. This paper distinguishes between truly renewable, sustainable sources of fuel from agricultural sources, i.e. biomass, and the disposal of domestic, urban and hazardous waste in energy-from-waste (EfW) plants; although these differences may appear to be marginal, and any EfW plant is of value for power generation, there are particular reasons why the generation of power from genuine biomass reaps environmental benefits. The bulk of the paper discusses the generation of electric power from a variety of different biomass substances, some from purpose-grown 'energy crops' but mostly from 'agricultural residues'. While this is predominantly through conventional combustion systems with steam turbines, more recent experience of both gasification and pyrolysis, with power generation by other prime movers, such as gas turbines and reciprocating engines is also covered. The concluding section of the paper looks briefly at the relative benefits of combustion, gasification and pyrolysis and what the future is likely to hold for each of these technologies.