A new piece of research into hydrogen heating backed by at least three gas companies has concluded that the use of hydrogen boilers is uneconomic and inefficient, even when taking the cost of grid upgrades into account.

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But the study, from the German government-funded Norddeutches Reallabor (NRL) project (loosely translated as the North German Living Lab), also found that waste heat from green hydrogen projects could provide a vital piece of the puzzle for decarbonising heat, if it is reused in district heat networks.

The conclusion was even more notable for the fact that the study forms part of a wider research project in which three gas companies — Dutch pipeline firm Gasunie, German company Gasnetz Hamburg and Hamburg-based distributor Hansegas — are partners.

The main thrust of the paper, Green hydrogen for the Energy Transition: the Building Sector, repeats the same findings as those laid out in the 37 independent studies on decarbonised heating compiled by energy researcher Jan Rosenow, specifically that the use of a hydrogen boiler to heat a building is significantly less efficient than direct electrification by a heat pump.

“The use of hydrogen for the decentralised provision of heat in buildings is generally not economical,” the NRL report reads. “The main reason is the inefficiency: in the existing building, five to six times more green electricity is required for the electrolysers compared to a scenario with heat pumps. The factor increases for modernised or new buildings.”

As a result, the authors warned, the use of hydrogen to heat buildings should not be prioritised, and reserved only for “exceptional situations”, such as to cover peak loads in heat networks or if there is no way of fitting a heat pump.

Hydrogen boilers are becoming increasingly controversial, especially in the UK, where a significant public backlash against a gas company-run hydrogen village trial has resulted in public protests and demands from residents for impartial advice.

But the NRL’s research is not independent, which is why it wasn’t included in Rosenow’s literature review, the energy researcher told Hydrogen Insight.

The study — just one in series of papers examining the role hydrogen could play in a variety of sectors — is carried out in partnership with around 50 organisations comprising universities, government and businesses, including Gasunie, Gasnetz Hamburg and Hansegas.

“Given the involvement of gas network companies the conclusions are even more notable I think,” Rosenow told Hydrogen Insight, although he warned that there is no way of knowing how much influence the partners had on this research.

Significantly, the NRL paper also pushed back against the notion often put forward by hydrogen heating proponents that the cost of upgrading the grid to accommodate extra demand from heat pumps — specifically the capability to handle peak demand — would be prohibitively expensive.

The researchers modelled a range of scenarios, acknowledging that heat pump power demand could increase peak loads on the grid by anything from 50% to 260% — which would indeed carry a significant cost.

But the reality of the gas network sharing heat demand with the power network would also raise costs for the reduced number of consumers left using the gas network, especially as the electricity grid is likely to need significant upgrades anyway.

“An upgrade and continued operation of the gas networks for a presumably very reduced hydrogen transport to the decentralised conversion to heat in residential areas would be at least from an economic point of view questionable and probably not more effective as a (possibly necessary anyway) upgrade of the power grid,” the report warned.

Nevertheless, hydrogen could still have a key role in decarbonising buildings, in the form of waste heat from electrolysers or fuel cells that could be fed into district heat networks or heat storage sites, known as heat sinks, the NRL said.

The study urged prospective green hydrogen producers to consider this option when choosing locations for their projects.

“Green hydrogen could become a piece of the puzzle for heat networks,” the study said, adding:

“The waste heat from electrolysers and fuel cells, which is necessary for the stability of the power grid and for the production of green hydrogen for other sectors, should be fed into heating grids to increase efficiency.”