MAKE Consulting said it now predicts 2010-2015 US wind capacity to be 42.8GW, cut from an earlier estimate of 55.6GW.
MAKE said it is downgrading the forecast because of poor macroeconomic conditions and an unfavourable policy environment.
The US had 36.2GW of installed capacity in July 2010. The new forecast would see capacity rise by 118%, for a total of 79GW at the end of 2015.
MAKE said US turbine sales are threatened by a slow economic recovery and continued low prices for natural gas.
This poses problems for both American and European manufacturers, because both are heavily reliant on US turbine sales, MAKE said.
The consultancy also predicts that Congress will fail to pass a federal renewable electricity standard (RES).
A bipartisan group of senators led by Democrat Jeff Bingaman of New Mexico last week introduced a new bill in another attempt to establish a national RES.
Electricity demand is also unlikely to reach 2007 levels until 2012, MAKE said.
All these factors will lead to fewer and lower priced power purchase agreements, especially in states that are meeting their RESs.
Even the revised forecast is likely to depend on a strong uptick in yearly installations after 2010.
New capacity installed between January and July of this year totalled 940MW, but MAKE’s forecast requires an average of over 7GW a year.
The country’s record year for wind installation, 2009, saw almost 9.5GW installed.