| Abstract |
Geothermal energy is a kind of green and low-carbon renewable energy. The application of geothermal energy to agricultural greenhouse heating can effectively solve the problems of high energy consumption and large carbon emission in traditional greenhouse heating system. In this work, a carbon footprint analysis model of geothermal greenhouse heating system is built based on life cycle assessment. This model can analyze the whole carbon footprint process including the extraction of geothermal energy in the middle and deep layer, compression and lifting, greenhouse end and plant absorption of carbon dioxide. Based on the experimental data collected during the heating period of XinSheng flower geothermal heating system in Xianyang area, the carbon emission per unit greenhouse heating area is calculated under different power generation technology (coal-burning power generation, gas-fired power generation) and different heat source. The results show that: 1) During the 2021-2022 heating period, the carbon footprint of heating unit area and unit time of an 80000m2 connected greenhouse in Xianyang area is 107.8 and 23.1 (m2·d), respectively, under coal-fired power generation and gas-fired power generation. 2) The carbon emission of gas-fired power generation as the driven power to the heat pumps is only 21.4% of that of coal-fired power generation. 3) During the heating period, the contribution rate of R134a leakage from the heat pump unit is 2.4% and 11.4% of the total carbon emissions under CFPP and GFPP, respectively. The development of new environmentally friendly refrigerants can reduce the carbon footprint of system heating. 4) Compared with oil-fired boiler heating system, the carbon footprint of middle-deep geothermal heating is 49.08% of its under coal-fired power generation; If gas fired power generation is used, the former is only 13.28% of the latter. In this paper, the carbon footprint of greenhouse per unit area per unit time calculated by coal-fired power generation and gas power generation is 84.2% and 30.6% of the carbon footprint calculated by Lilong C for solar greenhouse shallow ground source heat pump heating system, respectively. |