In Haßfurt, a small town in the middle of Mainfranken, a Bavarian region in Southern Germany on a clear, windy May day around 2 pm: The electrolyzer starts booming and hydrogen is being produced from wind power. The gas tank behind the hall fills up. Norbert Zösch, Managing Director of the local utility Stadtwerk Haßfurt, smiles: "On a day like this, we can produce gas very cheaply thanks to excess renewables". Then he opens the roller shutter of the tidy, rather inconspicuous hall on the outskirts of the town, filled with power lines, pipes and electronics.
Norbert Zösch and his team achieved a great pioneering work: They built one of the first larger plants to generate hydrogen from a surplus of renewables through electrolysis. This makes the utility not only a cleantech forerunner, but also of digitization: The control of the whole power-to-gas plant is split between controls on site and the control center of Next Kraftwerke's Virtual Power Plant in Cologne, some 360 km away.
But Next Kraftwerke’s involvement in Haßfurt does not only extend to aggregating and selling ancillary services from the electrolyzer: The VPP also delivers forecasts of local wind generation and the load on the local natural gas network. This way, the control center does not only supervise and control the flexibility potential of the hydrogen production but also the local energy landscape in order to schedule the optimal dispatch of the electrolyzer.
Since the end of 2016, the plant has been able to generate 220 m³ of hydrogen per hour through an electrolyzer with an installed capacity of 1.2 megawatts at an efficiency of around 70 percent. The product - combustible hydrogen gas - is then fed into Haßfurt’s natural gas network in a five-percent admixture. Gas customers who opt for the more climate-friendly wind gas tariff by project partner Greenpeace Energy, can then burn the mixture of natural gas and hydrogen in their gas heaters without any upgrades in their homes.
With Greenpeace Energy and Next Kraftwerke, the Stadtwerk Haßfurt has deliberately opted for companies in the energy sector that prefer achieving pioneer work before fast profits. Norbert Zösch explains the situation: "Due to the obligation of paying a surcharge on the utilized green electricity, the plant does not create much profit, but it covers its costs.”
Every 15 minutes, Next Kraftwerke delivers forecast data to the electrolyzer on PV and wind feed-in, gas and electricity consumption in Haßfurt and the gas consumption of the nearby malting plant. The receiving interface converts this data directly into control commands for the electrolyzer: Depending on price forecasts and the current utilization of the gas and electricity network, the VPP remotely starts and stops the electrolyzer from Cologne while at the same time standing by to deliver control reserve to the national grid at any given second.
Norbert Zösch especially appreciates Next Kraftwerke's professionalism and willingness to engage in dialogue: "Cooperation with Next Kraftwerke has developed positively over the operating period. Of course, we had some differences at the beginning: Next wants to optimise the sale of control reserve, we want to generate gas as cheaply as possible from renewables - that does not always work together. In the meantime, however, we have achieved good compromises in the control of our plant that are viable for both sides," says the Stadtwerk’s manager with a conciliatory smile.
Following this statement, Norbert Zösch takes a last look at the electrolyzer for today before his colleague closes the roller shutter. The plant continues to run with a now muted hum.