in one third of the waters between and depth would on average generate a further 80GW, i.e. 120GW in total. An estimate of the theoretical maximum potential of the United Kingdom's offshore wind resource in all waters to depth gives the average power as 2200GW. The first developments in United Kingdom offshore wind power came about through the now discontinued Non-Fossil Fuel Obligation (NFFO), leading to two wind farms, Blyth Offshore and Gunfleet sands. The NFFO was introduced as part of the Electricity Act 1989 and obliged United Kingdom electricity supply companies to secure specified amounts of electricity from non-fossil sources, which provided the initial spur for the commercial development of renewable energy in the United Kingdom. Offshore wind projects completed in 20102011 had a levelised cost of electricity of £136/MWh, which fell to £131/MWh for projects completed in 2012–14 and £121/MWh for projects approved in 20122014; the industry hopes to get the cost down to £100/MWh for projects approved in 2020. The construction price for offshore windfarms has fallen by almost a third since 2012 while technology improved and developers think a new generation of even larger turbines will enable yet more future cost reductions. In 2017 the UK built 53% of the 3.15 GW European offshore wind farm capacity. In 2020, Boris Johnson pledged that, by the end of the decade, offshore wind would generate enough energy to power every UK home. At the start of 2022 there was a total of 11.26 GW of installed offshore wind capacity. During 2022 an additional 3.2 GW of capacity was added with the commissioning of the Moray East, Triton Knoll and Hornsea Project Two wind farms. A further 13.6 GW of capacity is either under construction (Neart Na Gaoithe, Sofia, Seagreen & Doggerbank A) or has been awarded a Contract for Difference in Round 3 or Round 4. Round 1 In 1998, the British Wind Energy Association (now RenewableUK) began discussions with the government to draw up formal procedures for negotiating with the Crown Estate, the owner of almost all the United Kingdom coastline out to a distance of , to build offshore wind farms. The result was a set of guidelines published in 1999, to build "development" farms designed to give developers a chance to gain technical and environmental experience. The projects were limited to in size and with a maximum of 30 turbines. Locations were chosen by potential