(Bloomberg) Wind turbine installations will grow more slowly in the U.S., the world's second-largest market, because of an "unfavorable" policy environment and "adverse" macro-economic conditions, MAKE Consulting said.

Little or no growth is expected this year in the U.S., the Hoejbjerg, Denmark-based consultant said today on its website. MAKE Consulting lowered its forecast for wind turbine installations in the U.S. by 23% from 2010 to 2015.

"The slow recovery of the U.S. economy coupled with continued weakness in natural gas prices has provided a headwind for U.S. wind turbine sales," the industry consultant said. "After years of strong growth, the U.S. wind energy market is bracing itself for a precipitous drop in annual turbine installations."

Prices of natural gas, an energy source that complements wind energy, continue to be "weak," hurting wind turbine sales, MAKE said. In addition, efforts by some U.S. governors to revive federal legislation for renewable energy will probably not result in more funding, the consultant added.

Turbine installations in the U.S. may fall to 6 gigawatts this year from about 9 gigawatts in 2009, Bloomberg New Energy Finance said in August. Manufacturers of wind equipment are operating at 25% less than than full capacity, and poor demand is leading to lower prices for new orders.

Shares of Clipper Windpower Plc, the London-traded wind- turbine manufacturer, yesterday sank 30% after it said "significant" strain on its cash position is creating a "material uncertainty" about the company's operations. Vestas Wind Systems A/S sank for a fifth day in Copenhagen trading.