E.ON UK is researching and developing a giant battery to store electricity from wind farms and micro-generation at times when it is not needed by customers. The size of four shipping containers, the battery will store 1 MW of power for four hours. The work is being sponsored by the government. E.ON's researchers at its technology centre in Nottingham are testing the technology with smaller batteries. Once this stage is complete, they will move on to building a larger prototype. They expect to install it on the local network by autumn 2009. "By researching and developing this battery we can store the power generated by wind farms any time and then use it when our customers need it the most," says Bob Taylor of Energy Wholesale and Technology at E.ON. The storage system will also help the development of localised generation -- a school with solar panels could store the power generated at weekends and use it when the kids are back in school. Making battery storage economic has for many years proved elusive. For more than ten years UK company Innogy developed its Regenesys battery storage system using regenerative fuel cell technology with wind power applications in mind. Its 12 MW pilot plant, however, which had been built at Little Barford in Cambridgeshire, was never commissioned. In 2003, after technical difficulties, it abandoned the £2 million system; its German parent company, RWE, which by then had taken over Innogy, refused to commit further funding to complete the project. E.ON insists its technology is different from Regenesys.