Bioenergy is the energy contained in living organisms. Plants get bioenergy through photosynthesis while animals get it by consuming plants. Organic material containing bioenergy is known as biomass.
Bioenergy consists of organic matter derived from trees, plants, crops or from human, animal, municipal and industrial wastes.
In India, Bio energy occupies a significant share of the rural energy mix. Biomass fuels dominate rural energy consumption patterns, accounting for over 90 per cent of total energy consumed. Fuel wood is the preferred and dominant biomass source, accounting for 54 per cent of biomass fuels used in India. Even agricultural biomass, agro-residues and dung cake are being used.
According to MNRE, the current availability of biomass is estimated to be 500 million metric tonnes per year. There is an availability of about 120-150 million metric tonnes from agricultural and forest residue corresponding to 18,000 MW. In addition, 5000 MW can be generated from the bagasse generated from sugar mills. Despite the enormous amount of availability, by the end of 2010, the total installed capacity of biomass based power in India was only 2559 MW.
Currently bioenergy is used in the following forms.
- Traditional domestic use for household cooking, lighting and space heating;
- Traditional industrial use for processing tobacco, tea, bricks, etc.;
- Modern industrial use making use of technology-advanced thermal conversion; and
- Newer chemical conversion and biological conversions techniques such as fuel cell and biogas production respectively.
However, the most important bioenergy conversion technologies are:
Direct combustion process: Biomass is burnt in a boiler to generate steam which is further used to generate power. It is enough to meet the rural electricity demands, and is a substitute to fossil fuels. It is more economical and generates employment.
Co firing: This is an efficient and clean method to convert biomass to electricity. Co firing with coal reduces emission of carbon dioxide and sulphur dioxide in air.
Thermochemical process: This process is used to convert the original bioenergy feedstock into more convenient energy carriers such as producer gas, oil or methanol. This includes the following methods:
- Gasification; and
- Catalytic liquefaction.
Bio chemical process: micro organisms are used for treating and converting human generated organic waste, i.e. fermentation technologies for the production of biogas energy.
- Anaerobic fermentation;
- Methane production in landfills;
- Ethanol fermentation; and
- Bio diesel.
In India, technology has significantly advanced and is being made available locally. Even then, there are several technology initiatives around the world which need to be shared and assessed under a common technology platform.
For a developing country like India, exploitation of bioenergy will definitely have a positive impact on the energy requirement. It will provide energy security, reduce poverty by generating employment and reduce the levels of carbon dioxide emission.
India has a potential to generate 20 GW of electricity from biomass residue and can make a significant contribution to the growing energy need. To achieve this potential, various incentives like income tax holiday and concession in custom duty, and policy measures are being provided by the government.