Transition of Steam Utility Systems to Solid Biomass-Fuelled Boilers and Biomethane-Fuelled Fuel Cells in the Wet Pet Food Processing Industry

Abstract

This study highlights the CO_2e - emission reduction potentials and related economic consequences for changing the steam generation from fossil to renewable. Two different utility concepts are developed, including a steam accumulator for load management. The first concept integrates a solid biomass-fuelled boiler into an existing utility system with a natural gas boiler. The second concept uses a biomethane-fuelled fuel cell for the base load and a natural gas boiler as a backup boiler. A detailed process analysis and dimensioning of the technology and the accumulator is the basis for a dynamic simulation. In the simulation the steam accumulator volume is varied. In addition, the electricity usage of the fuel cell is optimized in terms of costs or emissions. The comprehensive simulation study is done for a pet food processing company having an average steam demand of 18,000 MWh at around 9 bar and 3 t/h. The results show that the CO_2e - emissions can be reduced up to 42 % by the transition to a solid biomass-fuelled boiler system and up to 27 % using a biomethane fuelled solid oxide fuel cell. This leads to an increase of the operating costs. The comparison of the reduction to the total costs resulted in 0.05 – 0.11 €/kg CO_2e - reduction per year for the biomass fuelled system and for the fuel cell in 0.69 – 1.14 €/kg CO_2e - reduction per year. To transfer these concepts to other cases, the scope of the study focused on covering a representative steam demand. The study shows that switching to renewable energy sources and implementing load management measures, emissions can be reduced at corresponding additional costs.