MidAmerican Energy Holdings Company 2011 / Scott Sinklier RISING MARKET The production tax credit, set to expire in 2012, is spurring wind-farm construction. The expiration of the federal production tax credit for renewable energy, scheduled to take effect at the end of 2012, is spurring a boomlet in the construction of wind farms.The federal production tax credit (PTC), an important economic incentive for developers of renewable-energy facilities, provides wind-farm owners with a 2.2¢/kWh tax credit for wind power generated during the first 10 years of a facility's operation. However, the legislation under which the PTC was most recently extended—the American
Arch dams, classically curved monoliths situated in narrow valleys, are not as common as other types of dams, such as embankment dams and gravity dams. ENR takes a look at some of the biggest arch dams in the world, both completed and under construction.