This paper outlines the results of a comprehensive life cycle study of the production of energy, in the form of biogas, using a small scale farm based cattle waste fed anaerobic digestion (AD) plant. The life cycle assessment (LCA) shows that in terms of environmental and energy impact the plant manufacture contributes very little to the whole life cycle impacts. The results show that compared with alternative energy supply the production and use of biogas is beneficial in terms of greenhouse gases and fossil fuel use. This is mainly due to the replacement of the alternative, kerosene, and from fertiliser production from the AD process. However, these benefits come at a cost to ecosystem health and the production of respiratory inorganics. These were found to be a result of ammonia emissions during the production phase of the biogas. These damages can be significantly reduced if further emission control measures are undertaken. (c) 2012 Elsevier Ltd. All rights reserved.