Blue hydrogen has no role to play in a carbon-free future because of the “quite high” greenhouse gas emissions released during its production, claims an academic paper published this week.

Production of blue hydrogen, which uses natural gas coupled with carbon capture and storage (CCS), creates a greenhouse gas footprint more than 20pc greater than burning natural gas or coal for heat and some 60pc greater than burning diesel oil for heat, according to the paper titled How green is blue hydrogen?, written by Robert Howarth of the Department of Ecology & Evolutionary Biology at Cornell University and Mark Jacobson of the Department of Civil & Environmental Engineering at Stanford University. The paper was published in Energy Science and Engineering magazine.

“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” Cornell/Stanford paper

“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,” the paper says. “Our analysis assumes that captured carbon dioxide can be stored indefinitely, an optimistic and unproven assumption. Even if true though, the use of blue hydrogen appears difficult to justify on climate grounds,” it says.

“Often, blue hydrogen is described as having zero or low greenhouse gas emissions. However, this is not true: not all of carbon dioxide emissions can be captured, and some carbon dioxide is emitted during the production of blue hydrogen,” the paper says.

Total CO₂ equivalent emissions for blue hydrogen are only 9-12pc less than for grey hydrogen—hydrogen produced from natural gas without CCS—the paper claims. “While carbon dioxide emissions are lower, fugitive methane emissions for blue hydrogen are higher than for grey hydrogen because of an increased use of natural gas to power the carbon capture.”

Howarth and Jacobson argue that—even in a best-case scenario for producing blue hydrogen using renewable electricity instead of natural gas to power the processes—“there really is no role for blue hydrogen in a carbon-free future”.

In that scenario, greenhouse gas emissions remain high, and there would also be a substantial consumption of renewable electricity, which represents an opportunity cost. “We believe the renewable electricity could be better used by society in other ways, replacing the use of fossil fuels,” the academics say.

 

 

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Author: Stuart Penson