Performance evaluation of ground source heat pump system for greenhouse heating in northern China

To investigate the technical, economic, and environmental performance of ground source heat pump system (GSHP) for greenhouse heating, a groundwater-style GSHP was studied in a Chinese solar greenhouse (G1) and a glass-covered multi-span greenhouse (G2) during 2007-2008 heating period in Beijing, China. The heating coefficient of performance (COP) of the GSHPs in G1 and G2 were 3.83 (from Oct. 10, 2007 to Mar.10, 2008) and 3.91 (from Oct.10, 2007 to Feb. 3, 2008), respectively. The daily heating cost per m(2) greenhouse floor were 0.016 US$ m(-2) d(-1) and 0.058 US$ m(-2) d(-1) in G1 and G2, respectively. The heating costs of G1 and G2 were lower than gas-fired heating system (GFH) by 8.9% and 11.4%, but were higher than coal-fired heating system (CFH) by 16.5% and 12.9%, respectively. Equivalent carbon dioxide (CO2) emission analysis showed that G1 and G2 reduced CO2 emission by 41.9% and 44.6%, respectively, compared with CFH, but increased by 46.1% and 43.5% compared with GFH during the entire heating period, assuming that the electricity consumed by G1 and G2 was generated in coal-fired power plant. However, if the electricity energy consumed by GSHP was generated by burning the gas, the GSHP, in fact, emitted 45.9% less CO2 than GFH in heating the greenhouse. The equivalent CO2 emission from G2 heating per m(2) area was 3.37 times of that from G1. The test demonstrated that the Chinese solar greenhouse had higher economic and environmental performances than the glass-covered multi-span greenhouse. (C) 2011 IAgrE. Published by Elsevier Ltd. All rights reserved.