Big batteries are little more than revenue-chasing grid-stabilisers. The challenge of decarbonising heating and transport, whilst addressing renewable energy’s intermittency, requires some joined up approaches and few technologies are able to bridge the electricity, gas and fuel sectors. Here’s (almost) everything you need to know about power-to-gas …


What is it?
Power-to-gas (P2G) is a means to store electrical energy as chemical energy in the form of hydrogen. The core technology in a P2G system is an electrolyser, which splits water into its component hydrogen and oxygen molecules by running an electrical current through it. Hydrogen molecules are attracted to one electrode catalyst and oxygen to the other.

Sounds like a fiddly way to do energy storage, why bother?
With more renewable energy sources being built volatility on the network is becoming a bigger problem. Instead of curtailing output of solar and wind generators, surplus renewable electricity can be fed into an electrolyser, helping to balance the electricity network. The resulting renewable hydrogen can then be used in a number of ways, by direct injection into the natural gas network, in combination with carbon dioxide to generate methane for adding to the natural gas network or producing renewable gas and fuel feedstocks, for direct fuelling of turbines during peak electricity generation or for refuelling fuel cell vehicles.

However, historically electricity per kWh has been more expensive than other forms of energy contributing to the cost of P2G, so it has been cheaper to make hydrogen, usually for industrial usage, from fossil fuels. But, electricity is like any other commodity, the more of it, the cheaper it becomes. Renewable energy generation plants have low operational costs. On top of that the variability of wind and solar has helped to drive electricity prices down since there are times when the wind blows and the sun shines but matching demand is absent. In parts of northern Europe when offshore wind turbines are generating at night, but there is virtually no demand, prices are moving into negative territory. Cheap electricity makes P2G increasingly economical.

On the technology side, suppliers of electrolysers and related fuel cell and P2G systems, have been achieving better efficiencies and have developed scalable systems, mainly through investment in polymer-electrolyte membrane/proton-exchange membrane (PEM) electrolysers, which promises cheaper electrolysis at scale.

Several universities as well as start-ups developing hydrogen production technology are working on electrocatalysts based on non-precious metals and electrolysers that require less electricity for the water-splitting reaction.

Who is using P2G?
A growing number of companies. They include small renewable energy plant owners. Also gas players: Engie in France and Northern Gas Networks in the UK have got something going on with P2G. Shell is installing a 10MW P2G plant, which is big, as the largest in operation right now are no more than 2MW in size. The supply chains that have built up around producing gases like hydrogen for industrial use, or providing the infrastructure for storing and moving natural gas and fuel around, on land and sea, not to mention the oil and gas producers themselves, all stand to benefit from P2G. It’s a gateway to the much talked about, though yet-to-be-witnessed ‘hydrogen economy’.

The ongoing cost reduction in renewable energy and gradual removal of subsidies as well as policy shifts targeting decarbonisation of heating and mobility could help unlock demand for P2G. From the 2020s there’s going to be a lot of older wind farms no longer receiving subsidy payments. Sticking a containerised P2G system close by could be one option. When electricity prices are low the surplus can be converted to hydrogen, with revenues coming from grid balancing and fuel sales for transport applications, for example. Imagine the taglines … ‘Renewable electrolysis. It’s a gas, gas, gas.’ Or, how about ‘In P2G “curtailment” is a dirty word’.

Visitors to ITM Power can experience first hand the company’s technology: its small fleet of fuel cell EVs can be powered on clean hydrogen, supplied with electricity from a local wind turbine

Enough! Who makes electrolysers and other equipment related to P2G?
A few players are now commercialising, or on the verge of commercialising, large-scale P2G systems, in the multi-megawatt range. They include the UK’s very own ITM Power, though Canadian player Hydrogenics claims more installed P2G capacity and sites than any other supplier. Siemens might be getting out of power and gas but is into offshore wind turbines, large batteries and power-to-gas. In 2017, Massachusetts-based Giner ELX was spun out to commercialise large-scale hydrogen production systems for renewable energy storage and other industrial applications, based on parent company Giner Inc’s PEM electrolysis technology. Giner ELX is targeting markets in the US, Europe as well as Asia. US start-up HyTech Power is also touting its pre-commercial electrolyser around suitable wind and solar plants in Europe.

Isn’t there enough going on stateside?
Not really, though Hydrogenics installed a few systems and ITM Power is doing some feasibility studies in the US and also in Canada. Europe is the place to do P2G and Germany, like all things renewables-related, is the epicentre. The ‘poster boy’ of P2G projects is Thüga, where thirteen companies have jointly invested the first P2G storage system, which has been injecting electrolytic-generated hydrogen into the German gas distribution network for the past four years.

At the heart of the system is ITM Power’s rapid response PEM electrolyser, which is providing grid balancing services in Germany’s secondary control market. When there is too much power in the electricity grid, the electrolyser can increase its output at the request of the transmission system operator. The plant absorbs the power and converts it into hydrogen.

That said, the UK is funding a few pilots and projects in the hydrogen space, including. Like Germany it uses a lot of natural gas and has a gas grid that can absorb surplus clean electricity and the UK needs to decarbonise heating and transport too. Expect hydrogen-friendly policies to emerge after 2020.

What about new or notable P2G projects and the installations?
The number is growing, year on year. Anything with an acronym is shorthand for publicly funded i.e. most of them, but you get the gist …

The Orkney Islands, off the coast of Scotland, have over 50MW of installed wind, wave and tidal capacity but community-owned wind turbines on the islands of Shapinsay and Eday, in the archipelago, lose 30% of their annual output from curtailment, limited by grid capacity restrictions in Orkney.

Otherwise-wasted electricity from the Shapinsay wind turbine will be used by the BIG HIT (Building Innovative Green Hydrogen Systems in an Isolated Territory) project to produce renewable hydrogen using a 1MW PEM electrolyser supplied by ITM Power. BIG HIT involves partners from six EU countries and has secured EU-level funding.

In May 2018, the first refuelling of a hydrogen vehicle in the Orkney Islands took place, one of a fleet of five zero emission, Renault Kangoo vans equipped with a Symbio hydrogen range extender at the ITM Power refuelling station in Hatston.

Windgas Haßfurt, owned by partners Greenpeace Energy and Städtische Betriebe Haßfurt, operates a 1.25MW PEM electrolyser from Siemens, which is used to stabilise the local Haßfurt power network in Germany, by drawing excess electricity from wind and solar plants on the power network. The plant provides frequency stabilization from the available primary and secondary operating reserve.

The clean hydrogen is fed into the general gas network, and is intended for combustion in residential, commercial, and industrial buildings.

Hydrogenics has supplied a 2.4MW PEM electrolyser system as part of an agreement with Wind to Gas Südermarsch in Brunsbüttel, Germany. The system, undergoing commissioning at present, will convert excess wind energy into hydrogen, which will be fed into the local natural gas pipeline, helping to reduce the region’s carbon footprint.

The Jupiter 1000 project is the first industrial demonstrator of P2G, with a 1MW capacity, and a methanation process with carbon capture. Green hydrogen will be produced using two electrolyser technologies (0.5MW alkaline and 0.5MW PEM), all from renewable energy. The carbon dioxide will be captured on a nearby industrial site.

After assessing the demonstrator when it comes online in 2019, GRTgaz, which operates natural gas infrastructure, and the other partners on Jupiter 1000, will work on future technical and economic standards of a full-sized installation of this type as part of preparations to commercialise P2G activity in France.

Shell is building the world’s largest hydrogen electrolysis plant at its Rhineland refinery, in Germany. With a peak capacity of 10MW the hydrogen will be used for the processing and upgrading of products at the refinery’s Wesseling as well as exploring application in other sectors. The Shell-led consortium, which includes ITM Power, SINTEF, Thinkstep and Element Energy has €10 million in EU-level funding. The project’s total investment, including integration into the refinery, is costing roughly €20 million.

The plant, named ‘Refhyne’ is scheduled to be in operation in 2020 and will be the first industrial scale test of the PEM technology process. If powered by renewable electricity, to help balance the grid, the green hydrogen will reduce the carbon intensity of the site, a key goal for Shell.

Global demand for hydrogen is expected to reach 50 million tonnes by 2025, mainly for industrial and transport applications. By 2030 hydrogen will need to originate from low carbon or renewable sources if decarbonisation of transport is to meaningfully occur. The Certifhy project in Europe is developing a Guarantee of Origin (GO) for green hydrogen scheme. In April 2018 the first GOs, as a result, were launched for sale EU-wide. CertifHy GOs provide information of the source of the product and allow hydrogen users to track product origin.

Four hydrogen producers including the industrial gas companies Air Liquide and Air Products, the chemical company Akzo Nobel, Air Products, the retailer Colruyt Group and the energy utility Uniper are having their production batches audited during the pilot.

It’s worth mentioning that for P2G to successfully commercialise, large-scale systems need to be piloted. In the UK, ITM

Northern Gas Networks has identified a site suitable on its gas grid for a 50-100MW P2G plant. (Image courtesy of NGN)

Power has been working with Northern Gas Networks to identify a suitable site on the utility’s gas grid to install a 50-100MW P2G system, which would be by far the largest if taken to the development stage.

The site in near Gateshead in north-east England is able to support P2G conversion year-round, through winter peak periods and lower demand in the summer months. In addition, the site’s proximity to the A1 road and Newcastle and Gateshead makes it suitable for locally exporting hydrogen to extend a national network of refuelling stations, enabling fuel cell electric vehicles to travel from London to Aberdeen.

One company banking on P2G and its synergistic qualities with wind in particular is Arranged, a Belgium company that has developed an unconventional wind turbine tower. Dualtower doubles up as hydrogen storage. Various cylindrical tanks, called constructive pressure vessels, can be assembled and built as a four-leg tower, more easily than conventional concrete towers the company claims. The company will source electrolysers, to combine the most efficient production equipment to pair with its hydrogen storage Dualtowers.