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