Hybrid power stations could ease grid fears

GERMANY: More support is needed to develop combined renewable power stations to reduce the need for high-voltage transmission networks, German renewables association Bundesverband Erneuerbare Energie has urged.

The comment was made after a report highlighted the potential for such power stations in the eastern state of Brandenburg. The state government commissioned the study as it has been concerned about how growing amounts of wind energy generation can be best absorbed into the regional electricity system. Some 4.46GW of wind is installed, with the potential for up to 9.4GW.

The study, by the BTU University in Cottbus, looked into the potential for hybrid power stations and "virtual" power stations. A hybrid power station involves combining several types of renewable energy - such as wind, solar and biomass or biogas - to create a power station with controllable output that has one feed-in point to the electricity network.

Virtual power stations would have the various renewables units located at different sites in the state or even in the country, so that the network operator at each plant location still has to cope with the variable input of each unit and risk of overload.

The researchers found that hybrid power stations would suit Brandenburg's situation. This is because the input capacity could be set at a level appropriate to the available local transmission capacity and input controlled to follow any required schedule.

The issue of incentives for hybrid power stations has been debated for some time; the Brandenburg state economy ministry commissioned a similar study by BTU in 2008. The latest study noted the lack of progress in implementing such systems.

Last year, the federal government said it would consider either a continuity of supply bonus for virtual power stations or an optional market premium for renewable electricity sold directly on the market outside the electricity feed-in support system. When the Renewable Energy Act was revised last summer, the government chose the market premium option.