Supercritical CO2 heat pumps for industrial decarbonization: a techno-economic analysis

The hard to abate sectors produce a quarter of the annual global CO2 emissions. Their decarbonization is, therefore, pivotal in tackling climate change. The main strategies for decarbonizing the hard to abate sectors include synthetic fuels, hydrogen and electrification. The electrification and the direct use of hydrogen strategies would require drastic changes for the end users’ production process. Synthetic fuels, on the other hand, present approximately the same chemical characteristics of fossil fuels, hence, their utilization would not require substantial modifications for the end users. This strategy is, for that reason, the most promising. In low temperature industries, however, the direct electrification of the thermal energy needs could immediately be feasible by substituting natural gas boilers (NGB) with supercritical CO2 heat pumps (SCO2HP). In the present work, the cost-effectiveness of such a strategy is assessed. To do so different indicators such as the levelized cost of heat and the annual CO2 emissions have been calculated. The results show that SCO2HPs could represent a very interesting option in terms of CO2 emissions reduction (up to -67%), due to their intrinsic renewable energy share. From the economic point of view, however, this solution presents serious drawbacks. The cash flow of the investment is, in fact, negative despite very optimistic technical assumptions for the SCO2HP. Moreover, a sensitivity analysis has also been performed. From which, it emerges that the cost-effectiveness of such a solution is strongly dependent on the price of the energy vectors, mainly natural gas and electricity. Specifically, just for the cash flow to be greater than zero, a 30% reduction of the electricity price would be required. Symmetrically, a 30% increase in the natural gas price could catalyse a shift from the NGB to the SCO2HP.