Source-to-sink Efficiency of Blue and Green District Heating and Hydrogen-based Heat Supply Systems

Hydrogen is commonly mentioned as a future proof energy carrier. Hydrogen supporters 6 advocate for repurposing existing natural gas grids for a sustainable hydrogen supply. While the 7 long-term vision of the hydrogen community is green hydrogen the community acknowledges that 8 in the short term it will be to large extent manufactured from natural gas, but in a decarbonized 9 way, giving it the name blue hydrogen. While hydrogen has a role to play in hard to decarbonize 10 sectors its role for building heating demands is doubtful, as mature and more energy efficient alter- 11 natives exist. As building heat supply infrastructures built today will operate for the decades to 12 come it is of highest importance to ensure that the most efficient and sustainable infrastructures are 13 chosen. This paper compares the source to sink efficiencies of hydrogen-based heat supply system 14 to a district heating system operating on the same primary energy source. The results show that a 15 natural gas-based district heating could be 267% more efficient, and consequently have significantly 16 lower global warming potential, than a blue hydrogen-based heat supply A renewable power-based 17 district heating could achieve above 440% higher efficiency than green hydrogen-based heat supply 18 system.