Offshore hydrogen production could become a reality in less than 10 years

Finn Daugaard Madsen stresses, however, that the goal line is still far away, and that there is therefore still a great need for research and development.

“In the past, we have optimized the turbine to make it as good as possible. And we have optimized the electrolysis to make it as efficient as possible. Now the two things have suddenly been linked together, so we have to optimize both at the same time. There are countless things that need to be tested, and we need our research institutions to help us,” he says.

“Siemens Gamesa and DTU are dependent on each other. We are dependent on the many good people in our organizations who can drive development in the right direction.”

Testing new materials

One of the people Finn Daugaard Madsen is alluding to is Henrik Lund Frandsen, a senior researcher at DTU who works with ceramic electrolysis. He is in dialogue with Siemens Gamesa regarding the hydrogen project in Brande, and works with other major players such as Haldor Topsøe.

Henrik Lund Frandsen notes that the biggest challenge with Power-to-X on the energy islands is that the hydrogen-producing electrolysis plants have to operate using the wind turbines’ fluctuating power production. Or in sector jargon: they run off-grid.

Normally an electrolysis plant is connected to the common power grid, where the power supply is constant, so the electrolysis cells can continuously split water into hydrogen and oxygen.

On the energy islands, the electrolysis plants will not be connected to the common power grid, and if the right solutions to control the turbines are not developed, it could have an impact on the power supply to electrolysis, which risks fluctuating as much as the wind. This makes it difficult to maintain stable operation, and places great demands on the materials used in the plants.

“If there are long periods without wind, there will be no power to produce hydrogen, and ultimately the plants will have to be shut down. When they need to start up again, they must first be warmed up. This causes wear on equipment and is expensive, because high-temperature electrolysis occurs at temperatures between 600 and 850°C,” explains Henrik Lund Frandsen.

However, calculations show that hydrogen production on the energy islands still has great economic benefits. Hydrogen is seven to ten times cheaper to transport ashore than electricity, and this is a large part of the total cost.

Henrik Lund Frandsen is therefore researching which materials are the most robust to use in electrolysis, so that fluctuations in wind, power input, and temperatures will cause the least possible disruption to operations and wear on plants.

“As things stand now, the materials used in the plant are best operated at a temperature of 750°C. If the temperature drops below this, the ceramic cells that produce the hydrogen operate sub-optimally, and if the temperature goes above this, we put strain on the steel lids used in the plants. If the power level wanders up and down, the various materials wear on each other, reducing the service life,” says Henrik Lund Frandsen.

He expects DTU to be ready within three years to test a dynamically adapted Power-to-X plant, that can last for five years before components have to be replaced. Current systems can last for two to three years.

Siemens Gamesa Fløvej Finn Daugaard Madsen — Power-to-X takes place inside an electrolysis plant like this. Power is supplied from a connected wind turbine to make electrolysis cells in the plant split water into oxygen and hydrogen. (Photo: Martin Dam Kristensen)

The Second X

The energy island plans have turned wind technology as we know it upside down, according to Kenneth Thomsen, Head of Wind Turbine Design at DTU. They have created a great need to re-develop and re-optimize wind turbines. He calls the principle Design for X.

“Design for X means that when designing a wind turbine we have to decide what it will be used for. We can implement the wind turbines we already have out near the energy islands. But when we look at the huge amounts of green power we are going to need, there is a major advantage in designing the turbines so that we can reduce their cost and thus also the price of the energy,” he explains.

Like the electrolysis plants, the crucial difference for the offshore wind turbines is that they will run off-grid. When wind turbines run off-grid, it means you can remove the power electronics in the turbine that normally adapt the electricity to the power grid, so that the frequency is 50 Hz alternating current.

This leads to major cost savings and opens up big new opportunities, according to Kenneth Thomsen.

"It will be relevant to look at the turbine generator and design it to produce direct current, because an electrolysis plant actually runs on direct current. This places new demands on the turbine. We can develop something here that will be used for the first time,” he says.

Development of a digital control system for the turbines will also be crucial to ensure the interplay between the turbine and electrolysis plant functions properly. It is this interplay that ultimately ensures stable and continuous hydrogen production.

‘We can do it again’

Returning to the wind turbine and electrolysis plant at Fløvej, Finn Daugaard Madsen is convinced that the first step in the coming offshore hydrogen adventure has only just been taken.

“Initially, the energy islands will be set up similarly to what we have here in Brande. The next step will be to develop a ‘hydrogen turbine’, which instead of supplying power to the electrolysis plant, generates hydrogen directly. Once we have hydrogen turbines up and running, we can use this hydrogen to make ammonia at a plant out there that can supply fuel to much of the shipping industry.”

Finn Daugaard Madsen estimates that Denmark will be ready to establish facilities on the energy islands similar to that at Fløevej within 7-10 years, but further exploitation of the full potential will require research, innovation, and collaboration.

Not only in relation to improving the robustness of the electrolysis plants and the technical design of the wind turbines, but also in relation to digital control of the energy system, storage of the energy, purification of the water for electrolysis, and establishment of the entire Power-to-X solution.

“If Denmark is going to position itself, as we have done before in relation to turbines, then cooperation, development, and production in many different areas will be needed. It will be a jigsaw puzzle to get these things to work out, so we ensure we always have power in the grid, charged batteries, and hydrogen in the tank,” says Finn Daugaard Madsen.

If you take a look around the world, especially towards China, the development of wind technology is happening at a rapid pace. This may cause doubt about whether it is even possible for Denmark to beat the major players. But Kenneth Thomsen is in no doubt. As a researcher who has worked with wind technology in Denmark for many years, he knows what a small nation like Denmark is capable of accomplishing.

“Back then, we got the opportunity to develop wind technology in Denmark while the rest of the world thought: ‘Let them try. It’s never going to succeed.’ But suddenly wind turbine technology was big business that could save the world. Now we have a need for green energy from solar and wind power in quantities we cannot even imagine. This demands special solutions, like the energy islands, and I believe we can do it again. Little Denmark can be the country that shows the rest of the world how to do it.”

Contact

Henrik Lund Frandsen Professor Department of Energy Conversion and Storage Mobile: 93 51 16 18? hlfr@dtu.dk

Kenneth Thomsen Head of Division, Wind Turbine Design Department of Wind and Energy Systems Mobile: +45 93511080 ktho@dtu.dk