Reductions in Energy Consumption and CO2 Emissions for Greenhouses Heated with Heat Pumps

In the greenhouse industry, it is essential to use energy efficiently by operating economically feasible heating systems instead of the traditional combustion-based heating systems. In our experiment, a heating system with household heat pumps was operated at nighttime. Another heating system with a kerosene heater was used as a comparison. We compared the energy consumption, energy utilization efficiency, CO2 emissions and energy costs of two heating systems. When the inside air temperature was maintained at around 16C while the outside air temperature ranged between -5C and 6C, the results showed that 1) the energy consumption was 25% to 65% lower in the greenhouse with heat pumps (Ghp) when compared to the greenhouse with a kerosene heater (Gkh), 2) the energy utilization efficiency of the heat pumps was 1.3 to 2.6 times higher than that of the kerosene heater, 3) CO2 emissions were reduced by 56% to 79% in the Ghp when compared to the Gkh, and 4) energy cost was lower in the Ghp when compared to the Gkh. These results indicate that the heat pump system is found more efficient than the kerosene heating system and economically feasible for greenhouse heating.