From a renewable energy perspective, biomass can be defined as:
Recent organic matter originally derived from plants as a result of the photosynthetic conversion process or from animals and which is destined to be utilised as a store of chemical energy to provide heat, electricity, or transport fuels.
Biomass resources include wood from plantation forests, residues from agricultural or forest production, and organic waste by-products from industry, domesticated animals, and human activities. The chemical energy contained in the biomass is derived from solar energy using the process of photosynthesis. (Photo means to do with light and synthesis is the putting together).
This is the process by which plants take in carbon dioxide and water from their surroundings and, using energy from sunlight, convert them into sugars, starches, cellulose, lignin etc which make up vegetable matter loosely termed carbohydrates (and shown for simplicity as [CH2O]). Oxygen is produced during photosynthesis and emitted to the atmosphere.
All plant matter on Earth, both terrestrial and marine, is formed using this process. Animals that consume plant material and even carnivorous species all depend directly or indirectly on photosynthesis. Thus many animal products and wastes can also be classified as forms of biomass if used for energy purposes.
Worldwide, photosynthesis produces approximately 220 billion tonnes (dry weight) of biomass per year. As an energy source, this represents many times the world’s current total energy use.
Approximately 10 percent of the planet’s energy requirements are currently met from biomass, mainly for cooking and heating in developing countries, but also increasingly for fuelling a growing number of large scale, modern biomass energy plants in industrialized countries.