Using solar energy to enhance biogas production from livestock residue - A case study of the Tongren biogas engineering pig farm in South China

Due to the rapid growth in the global energy demand and to the growing concerns regarding energy supply, more attention has been paid to the development of bioenergy, especially the one derived from anaerobic digestion. In our study we used solar energy to improve the efficiency of anaerobic fermentation at the Tongren Pig Farm in Haining city, Zhejiang province, China. Haining, located at 30 degrees 15'-30 degrees 35'N and 120 degrees 18'-120 degrees 52'E, has the average winter temperature of about 5 degrees C. At the farm, solar energy collectors, with a total area of 100.8 m(2) and a volume of 6 t water were installed to heat the water in fermentation digesters. Comparison shows that biogas production was 2540 m(3) more or 11.2% higher than that of the CK with no differences in the methane content, which can also be translated into a 14.3% increase of pig manure energy transformation efficiency. (c) 2013 Elsevier Ltd. All rights reserved.