Electricity means light, power and energy. Nobody wonders about the constantly available energy nor how it is generated and the technology behind it. Suppliers and network operators ensure that the right amounts of quality electricity flow smoothly from the power stations to companies and households 24/7 without interruptions and fluctuations.
Wemag AG, headquartered in Schwerin, is one of the major suppliers of electricity in the Hamburg Metropolitan Region. The company dates back to 1890 and led to the founding of the Hamburgische Elektricitäts-Werke (HEW). During the former GDR era, the company was organized as an energy combine and became Wemag AG in 1990.
New standards in energy supply
2014 marked the start of an innovative solution that sets new standards in energy supply. To this end, Wemag AG co-operated with the Berlin-based specialist Younicos and realized the largest commercial battery storage plant in Europe with a capacity of 5 MW/h and an installed capacity of 8 MW. In 2016, capacity was expanded to 15 MW/h. The power guaranteed to the grid operator has since been 10 MW.
The present storage plant consists of 215 interconnected battery cabinets full of lithium-ion batteries. The equipment is housed in an purpose-built facility in Schwerin to compensate network fluctuations and to give customers a quality supply regardless of divergent operating conditions in the power grid.
“The frequency of the current must stay within a relatively narrow range of between 49.8 and 50.2 Hz. This ensures that motors and machines work perfectly,” said Tobias Struck who is Manager of Energy Storage and Projects at Wemag AG and played a key role in installing the plant.
System offsets fluctuations
Supplying electrical energy to meet demand requires constant co-ordination and the power generation must always cover consumption. “This does not always work perfectly,” Struck explained. “The consequences are permanent fluctuations of network frequency, and this can be offset with our system. As a result, the customer receives electricity at a guaranteed quality level regardless of the supply and demand situation. “
But rising renewable energy consumption means adjusting frequency fluctuations is far more complex. Although wind and sun produce a clean current, changing weather conditions lead to considerable fluctuations. To provide the required power level at all times, conventional power plants have to run continuously and consume fossil fuels.
“As conventional coal-fired power plants can only be driven up and down very slowly, overproduction can require the shut-down of wind power plants,” said Struck, adding: “Batteries are optimal for buffering such short-term fluctuations. Thus, they create free capacity so that more electricity from renewable energy sources can be used.”
The guaranteed capacity of 10 MW means the battery power plant in Schwerin is comparable to a 100 MW gas turbine. The fully automated power plant does not require any operators on site. The building contains nine transformers, 18 inverters and two rooms with racks of Samsung lithium-ion batteries. One storage units offer a capacity of 5 MW while the second room contains only about half the number of racks and provides 10 MW. This shows the enormous progress storage technology has made since the facility was set up in 2014.
Compensating frequency fluctuations is only one of the battery storage power plant’s functions: “Another important advantage will become evident in case of a blackout,” said Struck. “The reconstruction of the power grid after a considerable grid failure is very difficult and cannot be achieved with conventional power plant technology. A large-scale field test demonstrated that our battery power plant is fully black start-up capable and able to build up a regional supply network in conjunction with a local gas power plant.”
The inconspicuous building in the Lankow district of Schwerin not only contributes to grid stability in the age of renewable energies. It also ensures faster restoration of power during a power cut. The unique technology from the Hamburg Metropolitan Region goes perfectly with wind power, solar energy and electric mobility in future.