Reformed methane key to producing hydrogen at scale
September 25, 2018
A UK project aimed at mixing hydrogen into natural gas supplies could be key to the decarbonisation of Europe’s energy system, writes Jeremy Bowden
WHAT: The HyNet project uses methane instead of surplus renewable energy as feedstock.
WHY: There is insufficient installed renewables capacity to support the latter option.
WHAT NEXT: Collaboration between HyNet and its European peers could expedite development.
A number of projects designed to decarbonise natural gas grids by adding hydrogen are making progress across Europe.
None appears to have the scale to make a significant impact on gas demand or carbon emissions in the near future, though UK gas distributor Cadent’s HyNet project in northwest England has emerged as a leader in the field. It aims to add 20% hydrogen to the natural gas supply of 2 million customers. This is by far the most ambitious project under way and such a scale is only possible if methane (rather than surplus renewable power) is used as a feedstock, the project’s manager, Andy Lewis of Cadent, told NewsBase Intelligence (NBI).
Decarbonising the gas grid is inevitably going to move up the priority list of European policymakers as they struggle to meet emissions targets. Hydrogen appears to be the best option, as existing up-, mid- and downstream assets can be used, making it cheaper than electrification. The National Grid has estimated that electrification would cost over GBP10,000 (US$13,000) per home, and would require six times the current generating capacity (which is currently about 55 GW) to meet peak winter heating demand.
Most hydrogen pilot projects use surplus renewable power to produce the hydrogen from electrolysis, but the process requires serious amounts of energy, and installed capacity is not yet at a point where sufficient excess exists to implement hydrogen production at scale. Reforming methane to produce hydrogen, on the other hand, is much cheaper and can more easily be done at scale given current resources, said Lewis, who project manages Keele University’s HyDeploy research project, as well as the HyNet project itself.
“The best way to produce hydrogen on a large scale in the short term is by reforming natural gas; reforming is far cheaper than electrolysis,” Lewis said. “Then in the longer term, as more renewables come online, we may eventually be able to produce significant quantities from the surpluses. But for the time being, only reforming can produce the volumes required to make any sort of difference [to CO2 emissions levels]. The capital required for renewables right now would be too much, and [the UK] has targets to meet.”
The HyNet project aims to produce 5-6 TWh per year of hydrogen to mix at up to 20% concentration into the gas supply of 2 million customers (including major industrial users) – compared with just a few hundred households in the case of competing European projects, which are all based on renewables and electrolysis.
Eventually the UK could be supplied by a network of hydrogen plants linked to offshore carbon capture and storage (CCS), according to Graham Bennett, DNV’s VP for business development for the UK and West Africa. “Hydrogen’s energy density is a third that of methane – so you would be using about the same amount of methane as today or slightly more,” he said.
Lewis said it was essential to start the ball rolling on CCS, which is needed to store the carbon produced as a by-product of methane reduction. “The Committee on Climate Change, Imperial College and other experts have all emphasised the need to employ CCS to ensure the least-cost route to decarbonisation. We need to store 20 million tonnes per year of CO2 in the 2030s, and we have to start somewhere. So we have to do something in the 2020s. We need to see a full-chain CCS system working,” he said.
HyNet’s carbon would be stored in Eni’s Hamilton field. “By keeping storage very close to the source of CO2 we keep the costs down, and these are further offset by the money saved by not having to decommission the field,” Lewis said. “We still need government support for this first-of-a-kind project, but CCS represents by far the best option in value for money terms. HyNet could remove 1 million tonnes of carbon from the heating system by the mid-2020s.”
The depleted Hamilton field can store up to 100 million tonnes of CO/CO2, with potentially space for another 1 billion tonnes at Centrica’s nearby Morecombe Bay fields.
An announcement from the UK’s CCS task force on the deployment pathway for CCS is anticipated towards the end of this year, though policy swings on CCS in the past will mean many potential investors remain wary, he added.
The weakest link
Extensive research at Keele on appliances, as part of the HyDeploy project, is ongoing, but indicates that almost all domestic and industrial appliances are safe at hydrogen concentrations of 20% or below.
“Since 1996, EU GAB regulations have required appliances to work on mixes of up to 23% hydrogen, although we are still physically testing every model,” Lewis said.
He added that while higher concentrations were fine with some appliances, over 20% hydrogen would begin to require replacement of the weakest boilers, “so we have to stop there for the time being.”
“The H21 project is assessing whether we can inject 100% hydrogen into the existing network – it can’t be done now, but could happen in the future … [the UK has] a world-class gas network that we should continue to use in the future.”
The hydrogen appears to behave predictably in the gas network. “Four injection points should be sufficient for the HyNet project,” Lewis went on. “The key thing is that it stays mixed with the natural gas. What you don’t want is a slug of hydrogen hitting your appliance. It doesn’t seem to float to the top and it disperses well within the natural gas. Fundamentally hydrogen is a smaller molecule, so it has the potential to leak out quicker, but as we change to polyethylene pipeline we are effectively future-proofing our network.”
Recent US studies suggest 5-15% hydrogen by volume is suitable in well maintained systems, while current European regulations allow between 0.1-12% hydrogen. Some countries such as Germany and US states such as California are also planning standalone grids to supply pure hydrogen to the transportation sector.
Lewis said HyNet and HyDeploy were sharing their research findings on hydrogen’s behaviour in networks and appliances with other major European projects that aim to mix hydrogen with natural gas in the grid. All of these schemes plan to use surplus renewables, however, rather than methane reforming, and they are on a far smaller scale.
The main collaborating projects are Engie’s GRHYD project in Dunkirk, France, which is looking at putting 10% hydrogen into the gas system to heat 200 homes plus a clinic, as well as fuelling a fleet of buses.
Eon is also involved in two power-to-gas projects in Germany (Falkenhagen and Hamburg-Reitbrook), and “they can already accept 10% hydrogen into quite a bit of their network,” said Lewis. A third major renewable/electrolysis project is Gasunie’s Amaland project in the Netherlands.
“We share research and are in regular contact particularly with the French project, which is ahead of us in some respects. A lot of learning is shared,” he said. “We see that the gas grid has a role to play in decarbonisation, and we are trying to demonstrate that and secure the role of our asset.”