In keeping with the theme of many of the features in this edition,†biogas†is far from a new technology, first developed over 150 years ago. However, to date its application has been largely in the developing world, now it is now being lauded as a possible solution to up to 40% of the United Kingdomís energy supply.
Biogas plants are fuelled by anaerobic digestion. This occurs when organic matter is broken down by bacteria in an oxygen free environment. This results in the creation of methane and carbon dioxide, two key greenhouse gases. Rather than escaping into the atmosphere to contribute to†climate change†these gases can be harnessed for cooking, lighting and electricity generation. It is cleaner than simply burning organic matter so also reduces particulates in the air from smoke.
A biogas plant basically consists of a container to store the organic matter, a means to collect the gas and a method of excluding air to ensure the conditions for anaerobic digestion.
Traditionally biogas has been used in the developing world. Its clean flame reduces smoke inhalation typical from wood fires, a major cause of respiratory and eye disease.
Large-scale facilities are in place in South Asia and†China†to supply rural areas with gas for cooking, using a mixture of dung and water from farmers own animals. The residue can also be used as fertiliser to improve crop yields.
The facilities can also generate further revenue through the creation of CDM (Clean Development Mechanisms) projects under the Kyoto Protocol and subsequent creation of carbon offsets.
This has been the case in Nepal where demand for fuel wood far outstrips supply leading to land degradation and damage to waterways. Coupled with the health risks from smoke inhalation and the time spent searching for firewood the need for alternative solutions was great.
The Biogas Sector Partnership (BSP) coordinated the installation of over 124,000 domestic biogas plants in Nepal between 1992 and 2005. During this time approximately 4% of the population converted to biogas and the sector now employees over 11,000 people.
More investigation is now underway to explore the applications of biogas in developed countries. A key limitation has been its relative cost, but with energy prices increasing and changes in policy it is becoming more viable.
Germany has encouraged the adoption of biogas facilities through the provision of high feed in tariffs. There are also facilities emerging in rural areas in Scandinavia and the United States. A key concern, however, has been whether these facilities truly run on waste rather than crops that would otherwise have been sold as fuel and lead to global increases in food prices.
In the United Kingdom a number of facilities were built in 1980s in response to increased oil prices, but many ceased to operate once the price fell. New incentives have been announced, to come into effect in 2011. It is speculated that this could see biogas supply almost half of Britainís heating needs by 2050, with up to 20 plants installed over the next year with a target of 1,000 by 2020. Compressed biogas could also be used in the transport sector.
It would seem that the time may finally be right for what has previously been an almost cottage industry energy generation technology to become mainstream.
© Article 13 -†November 2009
Also in this feature: