But because wind is so intermittent – last Thursday all our existing 5,500 turbines were producing only 1GW – Decc calculates that, to keep the grid functioning, we will need 17GW of reliable power from new gas-fired power stations to provide constantly available back-up for when the wind isn’t blowing. However, since Decc wants to see these CO2-emitters also phased out after 2030 – and they need to run for 30 years to justify their capital cost – no power company will want to build them.