In the north of Scotland, between the Orkney Islands, lies the islanders' latest achievement in the rough seas. A high-tech device that looks like a surfaced submarine. Long and narrow, half above and half below the surface of the water. However, the unusual steel colossus here has a completely different mission: It is a tidal turbine.
Under the water surface, two rotors turn left and right, like those of wind turbines. It is set in motion by the current, which is created by the alternation of ebb and flow. The turbine generates electricity in this way and is the pride of Neil Kermode from the European Marine Energy Center. This system alone supplies more than 2,000 households with electricity, he says – the size of a small town. It's the prototype. He wants to put a few more in the water.
From electricity receiver to electricity supplier
On the Orkney Islands, the energy transition has long been complete. Solar systems decorate the roofs, wind turbines turn. Individual next to houses, as a private energy supplier, large systems for the general power grid. "We are 100 percent independent and green here," says Richard Gauld, who has been involved in the development of wind turbines in various functions for three decades. Gauld stands on a small hill, on which five huge wheels are enthroned. "We were electricity receivers, now we are electricity suppliers."
Now we have to solve the next problem. Because on the Orkney Islands, they now produce far more electricity than they need themselves. They feed part of it into the national power grid, but the capacity of the cable is limited, so that huge amounts still go to waste. Electricity cannot be stored, used later or transported. At least not yet. To change that, Gauld might soon produce green ammonia on Orkney. "We need a technique to store green energy. I think ammonia is the way forward."
Advantage of ammonia over hydrogen
At the other end of the UK, in southern England, researchers from the Universities of Oxford and Cardiff have already set up a laboratory to test storage options using ammonia. Siemens is also there. Actually, only hydrogen is needed to store energy. "But hydrogen is difficult to store and transport," says Ian Wilkinson, project manager at Siemens. A detour is therefore needed: ammonia. They test the possibilities in the laboratory, which is set up under the open sky and looks like a small container village.
First, they produce hydrogen with electricity using an electrolysis process. Water is split into hydrogen and oxygen. If you only use electricity from renewable sources, as here, the hydrogen is considered CO2-free. Nitrogen is then added to the hydrogen, resulting in ammonia (NH3). "And we can fill that up in tanks, store it in bulk and ship it," says Wilkinson. "From areas that have a lot of green electricity to areas that have little."
However, ammonia is a dangerous gas. When inhaled in low concentrations, it has an irritating effect, in high concentrations it is corrosive and there is a risk of death. On the other hand, ammonia is already being used in large quantities around the world, for example as a fertilizer. Storing and transporting it is common practice. But researchers agree: you have to think about the problem when storing electricity.
Green ammonia instead of dirty marine diesel
The University of Oxford has other research groups. After all, it must be possible to use the stored energy again, wherever it is. And in Oxford they think primarily of shipping, which emits around one billion tons of CO2 a year. The aim was to use an ammonia engine to propel ships across the seas. But the researchers are already thinking about air traffic. Instead of kerosene, ammonia could also make aircraft turbines turn, allowing them to take off.
Of course, not only the British are researching the technology. Ammonia is being experimented with as an alternative to fossil fuels around the world. Prototypes of cars have already been developed. In the USA, the Amogy company recently presented its ammonia tractor and provided an insight into the technology. There's ammonia in the tank here. A small reactor on the stern splits it to recover the hydrogen. The hydrogen is then converted into water and electricity in the built-in fuel cell. The electricity in turn drives the tractor. And it should have the same power as a diesel. It is scheduled to hit the market in 2024.
Ammonia – from the Orkney Islands to the world
Theoretically, in a few years, the power for the tractor could come from the Orkney Islands. There the surplus of energy will increase anyway. In Scotland it was first converted into ammonia, packed in tanks and shipped to the USA. Filled into the tractor there at some point, on which the electricity is made available again. Weeks later and in a completely different place. Richard Gauld firmly believes in it. Even if it still needs some time to develop. But it's the future, he says.
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