Microanalysis of the benefits of China's family-size bio-digesters

The construction of 14 million family-size anaerobic bio-digesters is thought to have improved the farm economy of many rural households in China. The general view is that the use of a bio-digester will reduce expenditures on fuels and on fertilizers and pesticides, freeing up income that can be spent otherwise. The effect of using the residue of the digestion process is believed to increase farm produce also. Sound empirical support for these beliefs is, however, absent. Through the survey carried out for users and non-users in three villages (two in the Gansu province and one in the Sichuan province) it will be evident that the effects of the use of bio-digesters on the farm economy are often small if not non-existent. However, with appropriate support, the benefits can be significantly improved. Furthermore, the bio-digester contributes considerably to a more convenient lifestyle and an improved indoor environment. The benefits are not measured in terms of money, rather much appreciated by those who invested in a bio-digester. (C) 2009 Elsevier Ltd. All rights reserved.