Maryland-based utility Constellation Energy has claimed a world record for running an existing gas turbine on the highest hydrogen blend to date at 38%, although the test only lasted for a day.

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A Siemens turbine at the 753MW Hillabee combined-cycle natural-gas power station in Alabama, which began operating in 2010, received “only minor modifications” before the demonstration, which took place on 18 May, but was only announced yesterday.

However, the test only showed that the turbine can run on the blend, with no data released on what the long-term effect on equipment or performance would be if hydrogen was actually introduced in an operational plant.

Nitrogen oxide (NOx) emissions “did not increase” as a result of blending in H2 during the test, according to Constellation.

Last summer, two US medical associations warned against combusting hydrogen and methane together due to increased NOx emissions compared to burning just natural gas, decreasing air quality and presenting a health risk if used in households.

Hydrogen Insight has reached out to Constellation for more details on the test and its results.

The US Environmental Protection Agency has recently proposed co-firing a 30% green hydrogen blend as one of two routes existing natural gas power plants can take to decarbonise operations.

However, using renewable energy to create green hydrogen to be burned for power generation has been criticised as extremely inefficient compared to directly using wind or solar electricity — and significantly adding to energy costs — while having marginal emissions reduction benefits due to the lower energy content of the gas.

The counter-argument is that if green hydrogen can be produced from excess wind or solar that would otherwise be curtailed, it would not be inefficient, and the process could be used as a form of energy storage, albeit with round-trip energy losses of 54-82% (compared to 5-15% for batteries).

In the pink

While Constellation claims the title of the largest carbon-free power generator in the US, this is mostly down to their nuclear fleet of more than 19GW — the biggest in the country — which the company plans to use to make “pink” hydrogen.

In March, it started up a 1MW test facility, part-funded by the US Department of Energy (DOE), at the Nine Mile Point nuclear plant in New York state, which will produce enough H2 to cover the facility’s current needs (it is used as a coolant).

Pink H2 could be cheaper to produce than green, while still likely to access the full $3/kg clean hydrogen production tax credit based on lifecycle emissions intensity, according to recent analysis by bank Lazard.

Constellation says it is also part of three consortia — the Midwest Alliance for Clean Hydrogen (MachH2), Northeast Clean Hydrogen Hub and Mid-Atlantic Hydrogen Hub — that have submitted final applications for the DOE’s Regional Clean Hydrogen Hubs programme, which will fund between six and ten hubs from a $7bn federal pot.