Blending H2 into natural-gas networks in order to later extract it has been criticised as an inefficient and overly expensive proposal

 

UK energy regulator Ofgem has invested £49.1m ($63.1m) into three hydrogen projects focused on blending hydrogen into the country’s existing gas network — and de-blending it at the point of use.

 

The first project, HyNTS Compression, has been awarded £33.3m to test how compression systems on the grid will respond to 100% hydrogen.

 

The second, HyNTS Deblending for Transport Applications, aims to use £9.9m to create a fully functioning de-blending and refuelling facility to serve H₂ vehicles, with hydrogen supplied in an unspecified blend with methane.

 

Element 2, the hydrogen refuelling firm in the project consortium, tells Hydrogen Insight that the tested blend will range from 0-20% by volume. The trial will also be the first to test separation via “a novel membrane process” on a natural gas main.

 

The third, Velocity Design with Hydrogen, will use £5.9m to study hydrogen blending in gas distribution networks.

 

However, blending and transport of H₂ through existing gas networks is already controversial for a number of reasons.

 

One is that these pipelines were built to handle methane. Hydrogen is an extremely small, reactive molecule that causes embrittlement in metal pipes and is prone to leak from the smallest gaps in the network.

 

The UK has been decommissioning all iron “mains” (pipelines within 30 metres of buildings) since 2002 and replacing them with “hydrogen-ready” polyethylene pipelines. However, the impact of hydrogen on other parts of the grid, such as compressors and valves, is far less understood.

 

Blending is also considered a highly inefficient as a mode of transporting hydrogen, since if it were to be used as H₂, it would need to be separated at point of use.

 

This has already been highlighted by a report by Omani state-affiliated logistics group Asyad, which advised the Gulf country that “separation is not economically viable with today’s technology and such low blending ratios would have minimal emissions-saving benefits”.

 

Paul Martin, a chemical process engineer and a member of the Hydrogen Science Coalition, described the idea of de-blending hydrogen from fossil gas as “ridiculous”.

 

“The notion of delivering a gas by blending it into another gas on purpose, with the intention to ‘de-blend’ the gas at destination using [expensive] palladium membranes is, well, ridiculous,” he wrote on LinkedIn.

 

“And yes, the concept, using a host of different gas separation technologies, has already been studied, in detail, and found to be ridiculously expensive and energy intensive too.”

 

Also, the hydrogen used in fuel-cell vehicles needs to be of extremely high purity — even four parts per billion of hydrogen sulphide, a common impurity in raw natural gas, could destroy a fuel cell.

 

Even if the hydrogen is never separated, but combusted as part of the gas mix, it is expected to substantially drive up the price of gas. Green H₂ is extremely expensive compared to fossil gas, and British think-tank E3G estimates that a 20% blend by 2035 could raise consumer heating bills by 20% while only decreasing emissions by 7%.

 

The European gas association Eurogas has recently admitted that blending will only ever be a marginal solution due to the sheer cost.

 

However, the UK seems to have not yet given up on this route. Beyond the projects funded by Ofgem, the government is expected to make a decision this year on whether to allow a 20% hydrogen blend in the existing gas network. And it is also due to decide on what role H₂ will play — if any — in domestic heating by 2026.

 

Source:HydrogenInsight