Related Links: Production Tax Credit Extension Boosts Wind Sector Is Energy Tax Policy the Way to Drive the U.S. Climate Change Fight? Once again, uncertainty reigns over whether the federal production tax credit (PTC), which expired on Dec. 31 for wind and several other alternative energy industries, will be renewed.The credit, which has a long history of being temporarily renewed after expiration, pays 2.3¢ per kilowatt hour of generation to wind, geothermal and cloosed-loop biomass energy companies, and 1.1¢/kWh to municipal solid-waste and certain other alternative power firms. The payment period generally applies to the first 10 years of operation.
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.