Unfortunately, there is no way of making sure the wind only blows when we need it, but now a US energy company is to try and tackle the problem of storing energy from wind turbines to meet peak demands through an innovative new battery technology.

Xcel Energy announced last week that it will soon begin testing a one megawatt battery-storage system capable of storing wind energy and transferring it to the grid as required.

The company said that when fully charged the energy storage system could power up to 500 homes for over seven hours, allowing grid operators to better match the variable levels of energy generated by wind farms with demands from end users.

The system is to be tested at a windfarm in Minnesota and is expected to go live this October. It is based on 20 to 50-kilowatt sodium-sulfur batteries acquired from Japanese engineering firm NGK Insulators Ltd, which Xcel Energy said will be installed in a unit approximately the size of two semi-trailers and weighing around 80 tonnes. Together the battery modules will be able to store 7.2MW hours of energy, with a charge/discharge rate of one megawatt.

Consequently the batteries will charge up when the wind is blowing and then supplement the power supply from the wind farm when the wind drops.

Xcel Energy Chairman, President and CEO Dick Kelly said that the development of advanced battery technologies had a key role to play in improving the commercial and technical viability of both wind and solar power. "Energy storage is key to expanding the use of renewable energy," he said. "This technology has the potential to reduce the impact caused by the variability and limited predictability of wind energy generation. This [trial] will be very important to both us and our customers."