Life cycle assessment and shadow cost of steam produced by an industrial-sized high-temperature heat pump

Abstract

Heat pumps are considered to be a promising technology to mitigate industrial emissions from steam provision. In this work, an existing scale-up framework for generating life-cycle inventory data for residential heat pumps was tested if applicable to large-scale high-temperature heat pumps. The benchmark was experimental data from existing machinery. It was found that the scaling framework underestimated the total mass; thus, a new scaling framework was developed and was applied to data obtained from a test run of a commercially available high-temperature pump. A full life cycle assessment was performed by comparing two different steam pressure levels, 2 and 5-bar, produced by the high-temperature heat pump to relevant benchmarks, such as steam from a fossil fuel-driven steam boiler. Although greenhouse gas emissions were reduced by as much as 98% in the best-case scenario, other midpoint categories exhibited a more mixed result in which sometimes the heat pumps were favorable and at other times the benchmarks had a lower impact. An unexpected finding was that the working fluid and its leakage did not have a significant contribution to the global warming potential but it was almost solely responsible for the ozone depletion potential. Recommendations were derived on how to further improve the environmental impact of high-temperature heat pumps. Ultimately, the life cycle impact assessment results were converted into shadow price to allow for a comparison between different areas of protection and to give policymakers an estimate of the total externalized cost of the technology.