*7.1. Domestic Biogas*

In 1975, the Chinese governmen<sup>t</sup> began a household biogas mass implementation strategy. Units were being installed within a few years at a rate of 1.6 million per annum. The technology continued to be developed and implemented, and in 2005, China had 17 million digesters generating 6.5 billion m<sup>3</sup> of biogas per annum [11,27]. Importantly, one fifth of households in rural areas ge<sup>t</sup> electricity from biogas. In India, Nepal, Vietnam, and Sri Lanka, this trend of rapid installation of biogas units has repeated itself. There are currently more than 2 million family-sized units in service in India, and over 200,000 families move from the traditional fireplace to cooking and heating biogas per year [2].

#### *7.2. Biogas for Agricultural Use*

Meili village (province of Zhejiang, China) slaughters 28,000 pigs, 10,000 ducks, 1 million ducklings, and 100,000 chickens each year, and the wastewater is fed to an anaerobic digester that generates enough biogas for more than 300 households and 7200 tons of organic fertilizer each year (ISIS, 2006) [2]. A similar process is used in Linköping (Sweden), where the biogas is upgraded to vehicle fuel standard for all public transit vehicles in the city (>60 buses), converted to run on biogas in 2005 (IEA Biogas, undated) [104]. Throughout Ireland, wastewater from farms in Ballytobin and the food processing industry produce electrical and heat energy by anaerobic digesters for the local farming population. With gas turbines and combined heat and power, this plant produces an additional 150,000 kWh of electricity and 500,000 kWh of heat energy per annum (IEA Bioenergy, undated) [91].
