at present we have a subsidy-driven  renewable industry which gets money for generation and also for not generating, which is a licence to print money. It should be a requirement of all intermittent forms of generation to have a set percentage of available storage within the schemes proposed and so investing in the  infrastructure rather than just sucking money out of the public purse.  Storage of intermittently produced renewable energy is the only way to remove baseline coal, oil and nuclear power production from the grid. an industrialised country working only when the wind blows is not a possibility. There are few viable options. Gordon Murray refers to compressed air storage but this runs at an efficiency of 40 to 50% and at present requires air-tight caverns produced by solution mining of salt (Letters, May 7). I am aware of no such sites available in Scotland. Pumped storage is possible and exists but it is land-hungry and is about 65% efficient. Batteries can be used to even out load but are high-maintenance and have a limited life span. Fly wheels are useful for evening out wind production but useless for long-term storage.  Hydrogen production is possibly the best use for surplus power as it can be stored for later utilisation and gas-fired power stations can be built quickly and relatively cheaply. These displace normal fossil stations and produce only water as a  by-product. If located in urban settings their efficiency can be improved dramatically by using waste heat to heat homes and businesses. as a fuel source for vehicles, hydrogen could reduce or replace the need for oil and could be used as a fuel in homes.  Offshore production would require the gas to be pumped ashore but a network of pipes exist for oil/gas collection already and we have the expertise to do it. The present problem of balancing the grid with more than 20% wind power is resulting in constraining of supply when there is too much wind for the grid to cope. Localised hydrogen productio