Storage solutions for smart energy management

Whether from solar parks, wind turbines or biomass facilities, more and more of Germany's electrical power is coming from distributed and volatile sources.

SmartRegion Pellworm: unneeded wind and solar energy are stored in high-performance batteries and household heating systems © Schleswig-Holstein Netz AG

Unfortunately, the availability of wind and solar energy depends on the weather and time of day. In the future, smart grids, innovative storage technologies and energy management systems will enable us to make use of renewables only when they are needed, as well as keeping the power network stable.

Last year, setting a new record, one in four kilowatt hours of electricity consumed in Germany came from wind, solar, hydropower, biogas and geothermal power plants.

According to the German Energy and Water Association, a total of some 150 billion kWh were generated from renewable sources last year – and in the future, output from wind, solar, hydroelectric and biomass facilities will be even higher. Germany's federal government aims to meet some 80 percent of power needs from renewables by 2050.

This presents enormous challenges for the energy industry because it is expected that electricity will be generated by many small producers rather than in huge power stations; at the same time, power supply and demand must be kept in balance at all times.

Unfortunately, the wind doesn't always blow and the sun doesn't always shine when demand is highest.

On the island of Pellworm, a smart grid connects an existing hybrid wind and solar power station with a decentralised hybrid storage system for power and heat. If more power is generated than needed, it is sent to high-performance batteries, decentralised accumulators and household electric storage heaters.

These storage systems can then deliver the power whenever the weather is poor and there is little wind. Two new transformers keep the voltage constant in the system, regulating the voltage automatically to the required 400 volts, no matter how much electricity the wind and solar power systems deliver.

Controlled by an energy management system developed by researchers in the Advance System Technology AST branch of the Fraunhofer Institute for Optronics, System Technologies and Image Exploitation IOSB, the smart network ensures that energy generation and consumption remain in balance

"To succeed, Germany's 'Energiewende' – that is, the country's planned transition to a new energy economy – requires a smart energy system with storage facilities to compensate for fluctuations," says Prof Eicke Weber, spokesman for the Fraunhofer Energy Alliance and director of the Fraunhofer Institute for Solar Energy Systems ISE in Freiburg.

To capitalise on the full potential of environmentally friendly and sustainable power generation from solar energy and wind power will require more effective tuning of supply and demand to each other. Smart grids and new storage technologies and systems are needed to regulate both power generation and demand.

"One important aspect of this is to integrate modern information and communication technology in the power grid," clarifies Dr. Peter Bretschneider, who coordinates the Alliance's Intelligent Energy Grids group.