Uses of Biomass

Biomass can be used in two fundamental ways: directly (e.g. burning wood for heating and cooking) and indirectly (by conversion into a liquid or gaseous fuel, e.g. ethanol from sugar crops, biodiesel from vegetable oils, or biogas from landfills and animal waste). Direct use is often termed “traditional” use, and indirect use is often termed “modern” or “commercial” biomass use because it involves more advanced processes, such as gasification and electricity generation. Direct or traditional use predominates in the developing world, while indirect use (after transformation) is more common in the industrialised countries.

70% of all biomass in the world is used in the residential sector, while 14% is used in industry and 11% is transformed into electricity, heat, or another energy carrier such as liquid fuel or biogas. Biomass for electricity generation has a total usage in volume higher in the USA than in the whole of Europe combined, but consumption for heating is considerably lower. The use of biomass for both electricity generation and heat has tripled in the last 13 years in the 15 EU countries, growing from 1,218 ktoe to 5,341 ktoe for electricity and from 2,186 ktoe to 5,341 ktoe for heat. The majority of developing countries are located in warmer regions, and the use of biomass heat, other than for cooking and traditional heating, is limited to the supply of process heat in industry.

In rural areas, biomass fuels are mainly collected by users, whereas in urban areas they are mostly marketed after collection by urban authorities or their agents. Urban use is based on the collection and processing of large quantities of waste, mainly by municipal authorities for processing in central plants and distribution by commercial means.

Of all the forms of renewable energy, only hydropower exceeds the amount of electricity produced by bio energy; wind produces similar amounts of electricity to bio energy. Biomass electricity has a significant advantage in that it is the only established renewable resource which can provide baseload power. Hydropower and wind power are generated with lower capacity factors because the supplies of water and wind are irregular.

Biomass fuels have negligible sulphur content and therefore do not contribute to sulphur dioxide emissions, which cause acid rain. The combustion of biomass generally produces less ash than coal combustion, and the ash produced can be used as a soil additive on farm land to recycle material such as phosphorous and potassium.

The conversion of agricultural and forestry residues and municipal solid waste for energy production is an effective use of waste products that also reduces the significant problem of waste disposal, particularly in municipal areas.

On the negative side, the widespread use of wood from natural forests can cause deforestation and localised fuel wood scarcity, with serious ecological and social ramifications. This is currently occurring on a serious scale in Nepal, Southeast Asia, parts of India, South America, and in Sub-Saharan Africa.

Some biomass applications are not fully competitive at this stage. In electricity production, for example, there is strong competition from new, highly efficient natural gas-fired combined-cycle plants. However, the economics of biomass energy production are improving, and the growing concern about greenhouse gas emissions is making biomass energy more attractive.

Direct use: Combustion is the main process adopted for using biomass energy directly. The energy released can be used to provide heat and/or steam for cooking, space heating, and industrial processes. Combustion can also be used for indirect conversion of biomass energy, as for power generation.

Indirect use: There are various technologies for converting biomass into secondary energy such as electricity or bio power. The technologies of energy conversion of biomass energy have been developed primarily in the USA and the EU.