The decarbonisation of process heat in the German food and beverages industry

Abstract

Industrial decarbonisation has largely stagnated over the last years in Germany. A large share of Greenhouse Gas (GHG) emissions stem from the combustion of natural gas for producing higher temperature process heat. High-Temperature Heat Pumps (HTHPs) are an emerging technology that can upgrade waste heat with electrical input to high temperatures needed for the processes and thus can contribute to the electrification of industries. Hence, HTHP can significantly reduce GHG emissions stemming from the production of process heat. While residential heat pumps are widely commercially available due to lower temperature requirements, no HTHPs were installed in German industries in 2018 due to multiple technical, market, and knowledge barriers. HTHPs are expected to reach temperatures up to 250°C soon, making the food and beverages industry a suitable sector due to process temperature requirements at the lower industrial spectrum (<250°C). The International Energy Agency (IEA) outlines that HTHPs are a core emerging technology to replace fossil-fuel boilers in industry over the next decades. Thus, there is a large market ahead for manufacturers.

This study evaluates the techno-economic potential of HTHPs in the Germany food and beverages industry. Further, it evaluates the GHG emissions abatement potential in relation to total GHG emissions of the industrial sector. This study has a generalized and systemic scope, thus does neither consider specific case studies, nor performs process optimization. It follows a bottom-up approach to include process- and technology-specific information and scales it up to national level. This study uses two waste heat scenarios, first considering an average 45°C industrial waste heat availability as worst-case, and second considering direct exhaust temperatures as best-case scenario. The generic bottom-up approach results in limited, but more detailed, coverage which makes the results conservative estimates for the application potential of HTHPs in German industries.

The most energy-intensive sub-sectors of the German food and beverages industry are sugar production, meat processing, dairy processing, bakery products production and beer production, which together accounted for approximately 9333 kt-CO2-equivalents in 2020. The processes dominating the thermal energy demand are mainly pasteurisation, cooking, baking, evaporation, and drying processes, which require higher temperatures for the evaporation of liquids and boiling off bacteria. The thermodynamic efficiency, the COPs, of applying HTHPs to the processes lay between 1,7 – 4,8 for the worst-case scenario and 2,4 – 22,7 for the best-case scenario. The technical potential for 2018 results in 12 TWh. Between 3 - 5,5 TWh of electricity are required to cover the technical potential. The GHG emissions abatement potential lays between 52 - 855 kt-CO2-eq. This could mean a reduction of up to 9% of total GHG emissions of the five sub-branches. Due to very high electricity costs and an absent carbon tax in industry in 2018, the most cost-effective scenario (50 MW HTHP in the best-case) is not cost-competitive with the optimized fossil-fuel benchmark. The levelized cost of heat (LCOH) for this scenario is 37 €/MWh, of which approximately 67% are stemming from electricity costs. With a carbon tax of min. 48 €/t-CO2-eq. the switch to an HTHP becomes cost-competitive (incl. maintenance and investment costs). With an expected increase in carbon taxation, less efficient scenarios become cost competitive. By reducing the electricity price by 50%, the best-case scenario with the large HTHP is cost-competitive without a carbon tax. Hence, there is a strong correlation between electricity price and cost-competitiveness of HTHPs. It is expected that the emission factor of the German electricity mix will decrease further in the future and strive towards zero in the long-term, which will lead to substantial increase of GHG emissions abatement potential. When the emission factor for electricity is reduced by 38%, the GHG emissions abatement potential lays at 16% of total GHG emissions of the five sub-branches. The timely investment into HTHPs drastically reduces the risk of sunken costs and makes industrial decarbonisation efforts in this decade attractive from an industrial perspective. Subsidies, carbon taxation, and the reduction of electricity prices by for example removing the German renewable energy levy (EEG) can contribute to making low-carbon technologies such as HTHPs more competitive to fossil-fuel infrastructure that run on fossil fuels with low prices in the industrial sector. Industrial decarbonisation is highly relevant in Germany due to the recent tightening of industrial decarbonisation targets and the systemic demonstration of HTHPs potentials crucial to achieving the latter.