Prediction of Stirling-cycle-based heat pump performance and environmental footprint using exergy analysis and LCA

Compared to other heat pump systems, the Stirling-cycle-based heat pump has several benefits. The use of Stirling-cycle-based heat pumps in high temperature applications, e.g., above 120°C, and waste heat recovery at an industrial scale is of increasing interest due to the promising role in producing thermal energy with zero CO2 emissions.

This paper analyzes one such technology as developed by Olvondo Technology and installed at the pharmaceutical company AstraZeneca in Sweden. In this application, the heat pump uses roughly equal amounts of low temperature heat and electricity and generates 500 kW of steam at 10 bar. A scale-up to 750 kW with improved energy efficiency is ongoing. To develop and widen the use of a high-performance high temperature heat pump that is both economically and environmentally viable and attractive, various analysis tools such as exergy analysis and life cycle assessment (LCA) can be combined. The benefit of exergy analysis is that it not only quantifies losses of work potential but also identifies the source and location of these losses. To evaluate the performance of the Stirling-cycle-based heat pump the Total Cumulative Exergy Loss (TCExL) method is used. The TCExL method determines total exergy losses caused throughout the life cycle of the heat pump. Moreover, an LCA study using SimaPro is conducted, which provides insight into the different emissions and overall environmental footprint resulting from the construction, operation (for example, 1, 8, 15 years), and decommissioning phases of the heat pump. The combined results are compared with the results of a fossil fuel oil boiler (OB), bio-oil boiler (BOB), natural gas-fired boiler (NGB) and biogas boiler (BGB). The findings indicate that a Stirling-cycle-based heat pump is a sustainable alternative to fossil fuel-fired boilers.



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