In a study that could solidify the trend toward construction of gigantic windmills, scientists have concluded that the larger the wind turbine, the greener the electricity it produces. Their report appears in ACS' journal Environmental Science and Technology.

Marloes Caduff and colleagues point out that wind power is an increasingly popular source of electricity. It provides almost 2 percent of global electricity worldwide, a figure expected to approach 10 percent by 2020.

The size of the turbines also is increasing.

One study shows that the average size of commercial turbines has grown 10-fold in the last 30 years, from diameters of 50 feet in 1980 to nearly 500 feet today.

On the horizon: super-giant turbines approaching 1,000 feet in diameter. The authors wanted to determine whether building larger turbines makes wind energy more or less environmentally friendly.

Their study showed that bigger turbines do produce greener electricity - for two main reasons. First, manufacturers now have the knowledge, experience and technology to build big wind turbines with great efficiency.

Second, advanced materials and designs permit the efficient construction of large turbine blades that harness more wind without proportional increases in their mass or the masses of the tower and the nacelle that houses the generator.

That means more clean power without large increases in the amount of material needed for construction or fuel needed for transportation.