An energetic, economic and environmental evaluation of a dual-source heat pump water heater – A case study in Beijing

• The energy costs of heat pump are less than that of gas boiler when P e P ng < 1 COP ∙ q ng q e . • The upper limit of electricity-gas price ratio to ensure economic feasibility is 0.45 in this case. • The carbon emission of heat pump is less than that of gas boiler if f e < f ng ∙ q e ∙ C O P q ng . • The impact of two incentive modes on the economy of retrofit project was compared. Heat pump technology plays an important role in achieving the goal of carbon neutrality in the building section. This goal requires a large-scale adoption and diffusion of heat pump to achieve scale effects. Most researches concerning heat pump technology mainly focus on the technical optimization. However, the economic and environmental benefits are the key factors determining whether technology is adopted by users. In order to identify the favorable scenarios to use heat pump technology and encourage users to adopt heat pump technology, an energetic, economic and environmental evaluation approach from the life cycle perspective of heat pump retrofit project is proposed in this work. Then, by conducting a case study of a retrofit project that replaced gas boiler (GB) with Air-Flue gas Dual-Source Heat Pump (AFDSHP), the research finds that: (1) Coefficient of performance (COP) and energy price are the main factor determine the economic feasibility of heat pump retrofit project, and the energy costs of heat pump are less than gas boiler when electricity-gas price ratio meets P e P ng < 1 COP ∙ q ng q e ; (2) Because COP of heat pump can rarely reach 6 in actual operation, the retrofit project is economically feasible when the electricity-gas price ratio is below 0.45 in this case; (3) Under China’s average carbon trading prices in 2020, 0.064 RMB / k g , encouraging user to adopt heat pump technology by carbon trading mechanism can achieve the same effect as government subsidies; (4) Replacing gas boiler with heat pump can reduce carbon emission only when carbon emission coefficient of power generation meets f e < f ng ∙ q e ∙ C O P q ng , which is to prevent the carbon emission leaking from the energy end-user to the power generation sector and to prevent an increase of carbon emission. This paper offers recommendations to policy makers about developing appropriate incentive policies, and provides decision criteria to users about adoption of heat pump technology.