London - The growth of wind power generation is likely to slow over the next few years, hit by cutbacks in the budget subsidies in the US and Europe that have driven 15 years of construction, a report published on Wednesday showed.Held back by a struggling world economy and the failure to create commercial conditions which stimulate more green investment, the report by the Global Wind Energy Council (GWEC) and Greenpeace International expected growth of wind power would not accelerate again until after 2020.Global installed wind capacity reached 240GW at the end of 2011, it said, but 2013 looks like a difficult year for the sector amid a rocky environment for global financing."Absent a new means for putting a global price on carbon, new demand growth in the OECD borne on a strong economic recovery, or some other unforeseen development, the industry's rate of growth will slow substantially in the coming few years," the report said.However, cumulative installed capacity could still reach 759GW by 2020 - supplying up to 12% of global electricity - and continue to increase during the 2020s to reach 1 600GW by 2030, the report said.CapacityIf current market uncertainties are overcome in the near future, capacity could even top 1 150GW by 2020 and 2 500GW by 2030.China, the world's largest wind market, had total installed capacity of over 62GW in 2011. Growth will likely slow until after 2015, though it will still be the market leader."The phenomenal growth in the Chinese wind energy market has outstripped the ability of the grid and system operators to manage it," the report said, adding that over 10 billion kilowatt hours of wind power were lost last year because the grid had no capacity to absorb it.The International Energy Agency (IEA) has estimated that the Chinese market will see a decline in its rate of annual installations, resulting in total capacity of 179GW by 2020.GWEC said this was rather pessimistic given the Chinese government's commitment to developing wind power.Total installed capacity could instead reach 125GW by 2015, growing to 214GW by 2020 and 400GW by 2030, but infrastructure and transmission lines will need to improve to accommodate more wind power on the grid.Although new markets in Latin America, Africa and Asia are emerging, potential for growth in the medium to long term will not be huge, the report said.CreditThe US market grew by more than 30% last year, with a total installed capacity of 47GW. By 2020, new installations in North America could grow by 14GW per year to 2030.This compares to IEA estimates of 8GW a year to 2015, slowing to 6.7GW by 2020, and to 5.9GW from 2022 - 2029."All things point toward exceptional growth in 2012, although this is clouded by dim prospects for the 2013 market, depending on the fate of the production tax credit," the report said, referring to a federal tax credit for renewable energy which helped create more than $15bn a year investment in US wind farms since 2005.The credit is due to expire at the end of this year but there is pressure on the US Congress to extend it.Meanwhile, Europe's total installed capacity stood at 94.3GW in 2011 which should grow to 138GW by 2015 and then at a healthier rate to reach 211GW by 2020 and 372GW by 2030.