Heat pump's role in decarbonization of building thermal control in the US midwest

Climate change is the result of increased CO2 concentrations in the Earth’s atmosphere. Continued use of fossil fuels for heating in the Midwest will increase CO2 concentrations and result in negative effects to the environment and human health. It is essential that these emissions are reduced through the use of electric heat pump systems coupled with renewable electricity. Electricity in the US Midwest has primarily been generated through the use of fossil fuels such as coal and natural gas but in recent years low-carbon energy sources such as wind and hydro have supplied an increasing share. Thus, now is an ideal time to begin electrification efforts by converting fossil fuel heating systems to electric heat pumps. Over the period 2007-2019 the residential price of electricity has been increasing while the price of natural gas has been decreasing which has limited the economic feasibility of electric heat pump systems. However, the increasing share of low-carbon energy for electricity generation has increased the environmental benefit of these systems in the form of reduced CO2 emissions. The capital cost of an air-source heat pump (ASHP) is comparable to that of a natural gas furnace with central air conditioning (AC) making operating cost of these systems the largest factor for determining their economic feasibility. In northern states the colder climate lowers the operational efficiency of ASHP systems making them unfavorable in terms of cost relative to a natural gas furnace with central AC but in southern regions of the Midwest ASHP systems were found to reduce both cost and emissions over a 15-year lifetime. Many households in rural areas of the Midwest use propane as their primary heating fuel which is on average roughly twice as expensive as natural gas. These households using propane would likely see cost saving in addition to reduced emissions by switching to electric heat pump system. Improvements in heat pump performance, overcoming adoption barriers, and adopting policies that buffer long-term climate solutions against short-term price fluctuations are all needed. In part due to continuing decreases in carbon intensity of electricity, heat pump climate benefits can be substantial over project life cycles; however, there is no current policy mechanism to enable this benefit to be considered relative to short-run economic considerations.