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Turning an old leaf

Power from plants Walt Patterson Publisher: Royal Institute of International Affairs Price: Not stated

By P P S Gusain
Published: Wednesday 15 March 1995

-- (Credit: Malaya Karmakar)PLANTS support human life. Period. Today, a majority of people in the developing countries depend on fuelwood, dung, charcoal and agro-wastes for their cooking, heating and other energy requirements. A flicker of electricity is also produced from agricultural and other wastes.

Subsequent to the oil shock in the '70s, and the later growing realisation of the adverse environmental effects of using fossil fuels, there has been an upsurge of interest in developing renewable sources of energy, including biomass. This has resulted in many new and efficient technologies for generating and transmitting biomass energy. Simultaneously, new approaches to increasing productivity and availability of biomass have also emerged.

As a result of these recent technological innovations, combined with developments in agriculture and forestry, there is now an exciting possibility of developing integrated systems incorporating both fuel supply and conversion plants capable of high-efficiency electricity generation. The idea of an advanced method of electricity generation from wood and other biomass grown explicitly for this purpose (the so-called "energy crops") has passed the conceptual stage and is now on the threshold of being an economically viable and environmentally sustainable option.

Walt Patterson explores the current status and future prospects of biomass power in developed and developing countries from technical, economical and other relevant viewpoints, and analyses the major implications of their widespread use.

Conventional directly-fired power plants using agricultural, forestry, urban and industrial wastes and refuse are based on combustion technology, which simply burns bulk biomass in boilers to raise steam. These steam-turbine generators are usually small (generally 0.2 MW to 5 MW and up to 25 MW) and are inherently less efficient (less than 25 per cent).The more promising advanced technological options include gasification of biomass to produce fuel gas which can be used in diesel engines and gas turbines. The simpler gasifiers (5-100 KW), coupled with diesel engines, are best suited for smallscale electricity generation in developing countries. Low and high pressure gasifiers with gas turbines are suitable for use in larger plants ranging from 2-10 MW to 100 MW or more.

Some advanced biomass power projects and programmes are described briefly, with special reference to Hawaii, Finland, Sweden, Brazil, Spain, the UK, Denmark and Italy. Biomass power based on renewable energy sources has some clear environmental advantages (in terms of carbon emissions) over traditional electricity technologies. On the other hand, the use of biomass power on a large scale can have serious impacts on land use and quality of wildlife habitat and biodiversity. There are serious issues of food security, energy dependency -- especially for developing countries -- rural and regional development and conflicts of commercial and political interests which need to be addressed.

In the US and other industrialised countries, biomass power offers an escape from the dilemma of surplus agricultural production. Farmers can grow biomass fuel on land no longer being used to produce food. In many developing countries, according to the author, biomass power has even more potential because of faster biomass productivity and an ever increasing demand for electricity. This argument needs more substantiation.

One shortcoming of the book is that most of the information relates to industrialised countries, particularly the US. More information on developments in developing countries would have been welcome. It is a well written book: concise and lucid in style; avoiding jargon and excessive technical detail. It includes bar charts, graphs, simple process diagrams and box items which add to its readability and usefulness. In spite of many uncertainties and hurdles, there is an even chance that biomass power may become a reality in the not-so-distant future. The book presents an exciting idea in an interesting, authoritative and balanced manner, and is a great help for anyone who is interested in looking into innovative options for the future.

---P P S Gusain is with the Consortium of Rural Technology, New Delhi.

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