Producers of blue hydrogen made from fossil gas with carbon capture and storage (CCS) must prove they are able to capture at least 95% of the carbon dioxide released by the process — unless they have a good reason not to, a key UK regulator has said.

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New guidance from the UK’s Environment Agency (EA), the regulator responsible for environmental permitting for hydrogen plants, told producers that system design must demonstrate the ability to capture a “minimum” of 95% carbon dioxide.

Carbon capture rates would be measured as a yearly average, the regulator added.

But operators with a system designed to capture less than 95% of emissions might still be able to get an environmental permit from the EA if they can show that they have “justification” for a more carbon-intensive design, but gave no details as to what might qualify.

And the regulatory guidance does not apply to operators of small blue hydrogen facilities producing less than 100 tonnes of hydrogen per day.

This means that large UK blue hydrogen producers are likely to be compelled to use autothermal reformer technology to make H2 from methane.

An ATR unit produces hydrogen by injecting oxygen into fossil gas to crack it into methane molecules rather than splitting it with heat and steam, the method used in conventional steam methane reformation (SMR) technology. The ATR method results in a more concentrated, high-pressure stream of CO2 than that produced by SMR, making it relatively easy to capture.

As a result, a 95% capture rate is much more feasible with ATR than with SMR, which can capture around 90% of carbon emissions, according to the UK government.

However, Norway’s Equinor, which is championing blue hydrogen in the UK and Norway, has said that SMR can only cost-effectively capture around 60% of the carbon emissions resulting from the process.

Using an ATR with a gas-heated reformer — which reuses some of the heat from the ATR, improving its efficiency — can boost the carbon capture rate to 96%.

Both of the UK’s big-ticket blue hydrogen projects, the Equinor-led H2H Saltend and Progressive Energy’s HyNet NorthWest, envisage using ATR technology.

H2H Saltend wants to build a 600MW ATR unit at its site in Yorkshire, on the east coast of England, and Progressive intends to expand its planned 24MW ATR in northwest England to an eventual 700MW.

The EA’s regulatory guidance was developed with help from the UK’s hydrogen industry.

Aradhna Tandon, policy manager at trade association Energy UK said: “The industry needs a clear understanding of how these technologies will be regulated so it can be taken into account in early stages of our design and build processes.”