Utilization of waste heat from hydrogen production : A case study on the Botnia Link H2 Project in Luleå, Sweden

Abstract: The global hydrogen demand is steadily increasing, and one way of accelerating the green hydrogen supply is to stimulate the green hydrogen economy. Utilization of waste heat from hydrogen production can increase the profitability of produced green hydrogen. Therefore, the aim of this study is to propose a system for integration of waste heat on the district heating (DH) network in Luleå, Sweden. Furthermore, an economic evaluation of the proposed system was conducted. In this study, the system was developed and investigated for two cases i.e. for a PEM and alkaline electrolyzer with an installed capacity of 100 MW. A large-scale heat pump and a heat exchanger were further added to the system to integrate the waste heat on the DH-network, while simultaneously providing cooling to the electrolyzer stack. The system was modelled for static conditions in the software MATLAB, with retrieved hourly DH data from Luleå Energi. The results showed that 203 060 MWhth can be extracted from the PEM electrolyzer with a waste heat temperature of 79 oC, while 171 770 MWhth can be integrated on the DH network annually. For the alkaline electrolyzer, 310 630 MWhth can be extracted at a waste heat temperature of 80 oC, while 226 220 MWhth can be integrated on the DH annually. The overall system efficiency is 94.7 % and 88.4 % for PEM and alkaline connected systems, respectively. Furthermore, the Levelized Cost of Heat (LCOH) is 0.218 SEK/kWhth and 0.23 SEK/kWhth for a PEM and alkaline connected system, respectively. For future scenarios with fourth generation of DH-networks, it is predicted that the LCOH can reach 0.018 SEK/kWth for a PEM electrolyzer system, and 0.017 SEK/kWth for an alkaline electrolyzer system. One conclusion that can be drawn from this study is that the utilized heat from the proposed system is price competitive in comparison with other thermal energy sources.