From this tweet by the always excellent Energiewende Germany I learned about an article titled “Hydrogen plant starts storing wind energy in Germany“.
As is clear from the title, this is another project to use wind energy in times where demand can’t keep up with supply to make some hydrogen from water. That is the future for storage of surplus renewable energy, since the existing infrastructure can store massive amounts of hydrogen gas.
The German existing gas infrastructure could handle storage of up to 200 TWh, which is much more than the about 30 TWh an electricity system of 100% renewable would need. But to get that capacity, people need to start building these kind of plants that store electricity from wind or solar as hydrogen. We still have a decade or two to go until renewable gets to 100%, but it is still a good idea to start early.
Enertrag has opened the first plant like this in 2011. At the time with a capacity of only 500 kW. The new plant reported on in that article has 2 MW. And it is operated by E.ON, one of the “big four” German utilities that used to show no interest in renewable energy and leave the investment in the sector to citizen projects.
As the article notes, only about 50% of the energy from the surplus electricity can be stored in hydrogen.
But that is of course not a problem. In the many time slots where demand can’t keep up even now, the electricity would be wasted anyway. And in the few time slots without wind and solar available (the occasional cold November night) that stored energy will have a very high value on the market.
Over this weekend, many countries in Europe saw negative electricity prices, with France and its inflexible nuclear plants reaching minus 4 cent per kWh. People were paid good money if they used electricity, helping to reduce the supply overload. In such a time slot it doesn’t matter that only 50% of the energy will be stored. There is too much available in the first place.
And while the technology for making hydrogen may still be somewhat expensive (that 2 MW plant cost around $2 million), there is only a need to store around 5% of yearly demand. Spread that cost over all electricity over a feed-in tariff or some such policy, and it won’t matter much. Let’s also note that gas plant capacity is by far the cheapest to build of all power plants at only about EUR400 a kW, which helps save money on the cost of the whole system as well.
The idea involves flying a turbine in circles 800-1,950 feet up in the air, where winds are steadier and stronger than on the ground. Because most of the power in a traditional turbine is generated at the tips, these new generators would consist of a pair of such tips mounted to a wing. The wing flies in vertical circles, attached to the ground by a tether, which both carries the traction force of the wing, and transmits the electricity generated to the ground. A computer uses the flaps on the wing to control the flight.
It will also be possible to use similar wings in offshore areas, where the wing would be stowed atop a buoy until wind conditions are favorable. Then, the wing would take off like a helicopter, fly up to 1,300 feet high, generate electricity and then land once more on the buoy. Click on their website http://www.scfwindturbine.com for more information.