Energy and economic analysis of biogas heated livestock buildings

The possibility to cover the annual space-heating requirements of a typical swine nursery by the methane produced using a solar-assisted anaerobic digester of innovative design, is studied for two Greek areas. Simulation is used to predict the hourly temperature and relative humidity inside the early-weaned piglet unit, along with the heating energy requirements to keep indoor conditions within pigs' production space. The methane produced by the solar-assisted anaerobic digester is also calculated using a detailed simulation algorithm. The results showed that the methane produced from the solar-assisted anaerobic digester completely ensures not only full coverage of the annual space-heating requirements of the described piglet unit for both Greek areas, but also large methane surplus which could-be used in various other ways. A simple sensitivity analysis concerning the economics of the solar-assisted anaerobic dig ester indicated that its profitability strongly depends on to what extent the produced methane is used. (C) 2002 Elsevier Science Ltd. All rights reserved.