Study finds blue hydrogen may not be climate friendly

A study published August 12 in the journal Energy Science & Engineering finds that so-called blue hydrogen may not be as carbon-neutral as perceived.

Hydrogen development processes are categorised along a color spectrum. Green hydrogen is considered the most environmentally friendly, using renewable energy to power an electrolyser to split water into oxygen and hydrogen.

Blue hydrogen is considered low-carbon, not net-zero. That process uses natural gas and steam to draw out hydrogen. CO₂ is a byproduct which is sequestered using carbon capture and storage technology.

Grey hydrogen is like blue hydrogen, but without the carbon storage. In the report, grey hydrogen is considered the dominant process.

The authors – Robert Howarth and Mark Jacobson – described their report as the first peer-reviewed paper to examine greenhouse gas emissions from blue hydrogen.

“Far from being low carbon, greenhouse gas emissions from the production of blue hydrogen are quite high, particularly due to the release of fugitive methane,” they write.

Compared with grey hydrogen, the authors estimate that CO2 emissions from blue hydrogen are about 10% less. When including methane emissions in their assessment, they find the greenhouse gas footprint for blue hydrogen, however, is actually 20% higher than burning natural gas.

While based on a worst-case scenario, the authors find that “the use of blue hydrogen appears difficult to justify on climate grounds.”

Very few blue hydrogen projects are up and running. BP signed memoranda of understanding (MoU) with potential customers for its planned blue hydrogen plant in Teesside in northeast England on August 5.

The UK sees blue hydrogen as having a major role in decarbonising its hard-to-abate industries over the coming decades. With a 1-GW capacity, BP said the Teesside plant is expected to contribute 20% of the UK's blue hydrogen target for 2030.