Excess heat recovery: An invisible energy resource for the Swiss industry sector

Typically, 70% of the total final energy demand in the industry sector is used for process heat. A substantial share of this energy could be provided by excess heat recovery. This study evaluates the techno-economic excess heat recovery potential in the Swiss industry through exergy and energy analysis and provides an overview of the spatial distribution of the potential by temperature level. The specific costs and payback periods of excess heat recovery are analyzed by conventional and new measures, as well as the overall costs of sector-wide excess heat recovery. The overall mean energy and exergy efficiencies of the Swiss industry sector are estimated to be 61% and 27%, respectively. The total amount of potentially recoverable excess heat is estimated at 14 PJ per year, i.e. 12% of the total final energy and 24% of the total process heat demand of Swiss industry in 2016. However, the economic potential amounts to only 5% and 10% if a payback period of 3 and 4 years is assumed, respectively. Long payback times of heat recovery measures and a high percentage of low-quality and small heat streams were the most important barriers to energy efficiency improvement in Swiss industry. Furthermore, 30-40% of the steam demand in Swiss industry could be provided from excess heat in an economically viable manner, if all excess heat available at temperatures below 80 °C was utilized for steam generation using low pressure evaporation, vapor compression, and high temperature heat pump techniques. The results and the data provided in this study can be adapted to other regions of the world and can serve as a base for conducting more comprehensive analyses and formulating more effective policies.