Hydrogen made at the wind turbine
Both offshore wind and hydrogen generation are increasingly seen as central to global decarbonisation. And over the last year we’ve seen a striking increase in the number of linked proposals that seek to develop offshore wind farms that are at least partly devoted to making hydrogen. Most of these schemes envisage generating electricity at the turbine which is then taken onshore via a high voltage undersea cable. This electric power will then be fed into a large electrolyser complex onshore to make hydrogen for various uses.
An illustration of how a central electrolyser complex on a platform in the middle of the Aquaventus project might look
But the story is changing rapidly; we are seeing a striking increase in the number of schemes that propose to make hydrogen in the wind turbine itself or at a platform in the middle of the wind farm. Instead of electricity, the farm will feed hydrogen onshore via a pipeline and then directly to users or to a repurposed gas grid for wider distribution. Although these new schemes are still at an early stage, it looks probable that a substantial fraction of all offshore wind turbines will eventually make hydrogen rather than transmit electricity.
What is driving this largely unnoticed change in the plans of large offshore developers?
1, It is usually (much) cheaper to transport hydrogen than it is to move electricity.
2, Having the electrolyser in the turbine or on a nearby structure enables the electronics in the turbine to be simpler.
3, If making hydrogen is the ultimate purpose of the electricity made at the wind farm, then it may make sense never to attach the turbine to the grid. The advantages of this include cost – no need for a substation onshore, for example – and flexibility. There is no risk of enforced disconnection if the grid temporarily cannot handle the electricity that the turbine produces.
4, In addition, the hydrogen pipeline to the shore can act as a very efficient storage medium. The pressure can be increased and more hydrogen ‘packed’ into the pipeline.
1, Cheaper to transport hydrogen than electricity
Hydrogen is surprisingly easy to transport via pipeline. It can be compressed to approximately the same level as natural gas in conventional pipelines and flows more easily because of its lower viscosity. (But it does have a lower energy value per cubic metre at comparable pressures).
The German utility RWE wrote as follows about its proposed AquaSector project in the North Sea that will eventually make hydrogen offshore (see below for more details about this proposal).
Compared to the transport of electricity generated offshore, the hydrogen production at sea and the transport via pipeline could offer clear economic advantages. The pipeline could replace five High Voltage Direct Current (HVDC) transmission systems, which would otherwise have to be built. It is by far the most cost-effective option for transporting large volumes of energy over long distances.[1]
One of the largest offshore hydrogen schemes is likely to be NortH2 in the Netherlands sector. The developers say this[2]:
As wind turbines are placed further out to sea, hydrogen production close to the source becomes more attractive. After all, the generated energy must also be transported to land. This can be done via heavy electricity cables, but it is cheaper and more efficient to transport hydrogen gas molecules. That is why NortH2 is also looking at possibilities to convert the generated wind power into hydrogen directly at the wind turbines: electrolysis at sea.
Siemens, which makes many of the offshore wind turbines now being installed around the world, seems to be convinced of the operational advantages of putting the electrolysis process either into the turbine itself or close by. One of its recent presentations suggests three reasons for favouring transporting hydrogen rather than electricity including the following comment. [3]
* Capex reduction by replacing high cost HV infrastructure with pipes network
The precise cost of transport to shore will depend on the distance and the complexity of linking to the hydrogen users or to the gas grid. The EU offered a recent estimate of around 5 Euro cents per kilometre per megawatt hour of energy.[4]This implies a cost of about €6/MWh for a 100 km link. The number was based on earlier research by Bloomberg NEF.
Other experts, including the CEO of the Italian gas distributor Snam, offer much lower figures suggesting that hydrogen transport by pipeline can cost as little as one eighth as much as electricity transfer.[5] (However this largely assumes using existing natural gas pipelines).
Unlike the transmission of electricity, which will always see losses of power in the transmission process and in the conversion from one voltage to another, hydrogen can be transported in gaseous form almost without loss.
2, Simpler electronics in the turbine itself.
A wind turbine connected to the grid, even via a long undersea cable, requires substantial electronic equipment to condition the power that is generated. Second by second, the varying amounts of electricity being produced have to be converted to a standard voltage and aligned to the frequency of the grid. This means that the power coming from the turbine requires substantial manipulation before it can be connected to the grid. The equipment required is costly.
3, Less equipment onshore and complete independence from the requirements of the electricity grid.
As renewables grow around the world, the percentage of time that wind turbines produce power which cannot be accepted by the national or regional grid is tending to rise. At these times the electricity is wasted. One of the attractions of not connecting turbines to the electricity system and directly making hydrogen instead is that all the power produced will be productively used.
In addition, there will be no need for a substation or substations onshore that connects the power coming in from the wind farm to the main grid. The hydrogen can either be connected to a gas network or used directly by customers such as an oil refinery, a steel plant or a fertiliser manufacturer.
4, The hydrogen pipeline can act as storage.
Natural gas pipeline networks can reduce or increase the pressure in their pipes to provide a buffer between supply and the demand for energy. The same will be true of hydrogen pipelines. When the wind is blowing and the turbine is making hydrogen but customers only need their standard amounts of the gas, it will make good sense to store the temporary surplus in the pipeline. Marco Alverà of Snam says that I kilometre of pipeline can store 12 tonnes of hydrogen, with an energy value of around 400 MWh.[6] Batteries can in theory provide the same service for a turbine that produces electricity but the cost for an storage capacity equivalent to a kilometre of hydrogen pipeline would be fifty million dollars or more.
The routes to a full coupling of offshore wind and hydrogen.
Let’s now look in a little more detail at some of the main pilot projects to produce hydrogen directly at the turbine or at central node in a wind farm. We will start with early experiments that are precursors to full hydrogen production and then move through to some of the outline plans for gigawatt-scale projects. All the schemes I could find were in Europe.
Denmark: a trial to show that a wind turbine can directly power an electrolyser while unconnected to the grid.
At Brande in Denmark, close to the its Danish headquarters, Siemens is trialling joint operation of a 3 MW onshore wind turbine and an electrolyser.[7] One of the most important features of the experiment is the attempt to show that the turbine can be ‘islanded’, meaning it can power the electrolyser without any grid connection, thus replicating how an offshore turbine without the means to connect to the electricity network can make hydrogen. The hydrogen from Brande will be used to power Copenhagen’s fleet of fuel cell taxis.
The site for hydrogen production from an islanded onshore turbine at Brande, Denmark
Perhaps more importantly, Siemens’ wind business is also investing heavily in the development of a variant of its largest offshore turbine that that will incorporate an electrolyser in the base of the tower. This work is being supported by the Siemens division that makes electrolysers.
The Netherlands: installation of an electrolyser on an existing natural gas platform.
The PosHYdon project in the Netherlands North Sea will use an existing natural gas platform to host a 1.25 MW NEL electrolyser, making a maximum of about 500 kilogrammes of hydrogen a day from water that has been demineralised.[8]The hydrogen will be added to the natural gas produced at the platform which will then be piped onshore. (Domestic appliances can burn natural gas that contains some hydrogen. The percentages that are allowed vary from country to country).
This trial will not use electricity from a nearby wind turbine but instead will use power that has been delivered to the platform from onshore. The installation is one of the few fully electrified offshore oil and gas platforms in the world.
An image of how an electrolyser might look on the Dutch offshore gas platform
The experiment will test the durability of a NEL electrolyser in a rugged marine environment and also examine how well the electrolyser copes with sharp variations in the availability of power.
The project is backed by a large number of energy companies and science research funds of the Netherlands government.
Norway: making hydrogen in times of surplus electricity and storing it on the sea-floor.
A pilot project will use seawater to make hydrogen close to an offshore wind farm in periods when electricity is in excess supply.[9] The hydrogen will be made and stored on the sea floor. Fuel cells will convert the gas back into electricity at the wind farm at times of shortage. In this case hydrogen does not avoid the need for electricity transmission. Instead it uses the gas to help make electricity supply more reliable.
This scheme is still at an early stage but involves a large number of partners with strong interests in hydrogen, including Finnish utility Vattenfall and Spanish oil company Repsol. It is being led by Technip FMC, a leading supplier of equipment for undersea oil exploration. The €9m project is being part-funded by Innovation Norway.
Underwater electrolyses and fuel cells in the projected Technip FMC scheme
UK: A trial project to make hydrogen on a floating offshore wind turbine base.
One of the potential advantages of using floating turbines for hydrogen production is that the turbine base provides a horizontal surface on which to place the electrolyser and other equipment. It may be easier and more economical to use floaters than fixed foundation turbines. Consulting firm ERM has received funding to develop a trial site in the middle part of this decade that will install a large 10 MW turbine, probably off the Scottish coast, to make hydrogen.
The design of the ERM floating turbine with hydrogen electrolyser
ERM’s technology may be used at a much larger Scottish wind farm.[10] The company recently signed a memorandum of understanding with the developers of a 200 MW project that will be constructed before 2030. The Scottish gas grid operator SGN is also part of the possible scheme to use floating turbines to make hydrogen to be piped onshore.
Italy: making electricity and hydrogen from an offshore wind and solar site.
The engineering company Saipem and its partners intends to make hydrogen at a new 450 MW offshore wind and offshore solar site in the Adriatic Sea off Ravenna.[11] The offshore farms will have an electrical connection to the mainland but also make hydrogen on converted offshore oil and gas platforms that will be decommissioned. The hydrogen will be piped both to the shore, and thus to the local natural gas network, and to marine refuelling platform that will accommodate ships that will transport the hydrogen to other locations.
A illustration of some aspects of the Saipem project, including offshore hydrogen production and hydrogen transport ship.
Netherlands: investigation of the opportunity to directly produce hydrogen at an offshore wind farm.
NortH2, a much larger Dutch project, is examining the options for directly making hydrogen from wind turbines.[12] It envisages as much as 4 GW offshore wind capacity in the Netherlands North Sea by 2030. In the early design, the power will be transported to a port on the Dutch coast but the consortium is backing research that looks at making hydrogen either at the turbines, on a platform shared between many turbines or at a man-made island close to the wind farm. This scheme is backed by the Norwegian oil company Equinor, Shell and several other entities including the innovative Netherlands gas grid operator Gasunie.
Germany
Aquaventus is the most ambitious of all European projects for making hydrogen offshore.[13] The scheme proposes eventually to use 10 GW of offshore wind to make hydrogen to be transported by pipeline to the German island of Heligoland. The first phase of this enormous scheme involves the installation of about 300 MW of offshore wind, producing about 20,000 tonnes of hydrogen a year by 2028. (Current global demand for hydrogen is about 70 million tonnes, and this is likely to rise sharply).
The partners behind the Aquaventus project, which include the utility RWE and Shell, regard it as a ‘proof of concept’ for the larger set of wind farms to be built by 2035, all of which will be connected to Heligoland by hydrogen pipeline. The gas will then be piped to mainland Germany.
An illustration of the 10 GW wind farm feeding hydrogen into north west Germany via Heligoland
In almost all respects this scheme seems similar to existing plans for North Sea wind farms producing electricity with the only difference being the generation of hydrogen. If it comes to fruition it will show that direct production of hydrogen at wind farms may eventually be as financially attractive as the conventional model of producing electricity.
What can we conclude from these diverse experiments and pilot projects?
Although some participants in these pilots are still checking that electrolysis at sea is possible and makes financial sense, there seems to be an increasingly strong view that a large fraction of total hydrogen supply will come from offshore wind turbines. Many of the largest European utilities are heavily involved in the project proposals.
Underlying this view is the sense that the demand for hydrogen will be sufficiently broad to make investment in direct manufacture at renewables sites an attractive proposition. The usual objection to making hydrogen from renewables is the loss in energy value resulting from the electrolysis process. But if the market needs huge quantities it is not a question of whether hydrogen should be manufactured but how best to do this. The number of large companies crowding into the hydrogen from offshore wind business suggests a high confidence that many millions of tonnes of hydrogen will be needed.
[2] https://www.north2.eu/en/blog-en/offshore-electrolysis/
[5] This information is taken from Marco Alverà’s forthcoming book, The Hydrogen Revolution.
[6] Marco Alverà in The Hydrogen Revolution.
[7] https://www.siemensgamesa.com/en-int/products-and-services/hybrid-and-storage/green-hydrogen
[8] https://poshydon.com/en/home-en/
[9] https://www.energyvoice.com/renewables-energy-transition/hydrogen/289798/technip-fmc-offshore-green-hydrogen/
[10] https://www.offshorewind.biz/2021/08/04/scottish-floating-wind-project-forms-green-hydrogen-tie-up/
[11] https://www.saipem.com/en/media/news/2020-08-25/saipem-protagonist-offshore-wind-will-develop-wind-farm-italy
https://www.agnespower.com/en/progetto-adriatico/
[12] https://www.north2.eu/en/blog-en/offshore-electrolysis/
[13] https://www.rwe.com/en/press/rwe-renewables/2021-07-23-aquasector-partnership-on-first-large-scale-offshore-park-for-green-hydrogen-in-germany