The future of low carbon industrial process heat: A comparison between solar thermal and heat pumps

Low carbon heat generation is now a major concern for many industries to achieve sustainability targets, however, it is not always clear which renewable or low carbon process heat technology is the most economical. This article develops a techno-economic assessment methodology to compare the cost effectiveness of solar thermal and electricity powered vapor compression heat pumps for process heat generation. Using key investment and performance indicators, it clearly elucidates the lower cost renewable or low carbon heat technology under most conditions found in low temperature industries. The analysis also calculates the maximum turn-key specific investment, inclusive of all material, labor, and financial costs, for solar thermal to remain financially competitive against heat pumps, serving as a target for the solar thermal industry. The methodology, which is independent of plant size, process temperature, and technology, reveals key results when applied to three cities in Europe of varying solar irradiation and current electricity costs. In Seville, the maximum turn-key specific solar investment is typically greater than 500 €/m2ap, meaning that solar thermal will most likely provide lower cost heat than heat pumps. The case for Stockholm is the opposite, with the maximum investment being primarily less than 300 €/m2ap, a challenging turn-key solar plant investment target that leads to the superiority of heat pumps in this region. There is a wide range (230-1000 €/m2ap) of maximum turn-key solar thermal investment figures for a central German location (Würzburg), indicating that either technology could be selected, but this is highly dependent on the process and other boundary conditions. Therefore, at any time now or in the future, the developed methodology can flexibly compare solar thermal and heat pumps so that the lower cost process heat technology can quickly be selected, while also providing a plant investment target for the solar thermal industry.