New rules proposed by the Environmental Protection Agency could put a choke hold on the construction of new, conventional coal-fired powerplants, industry sources say. On March 27, the EPA proposed the first-ever Clean Air Act standard for carbon emissions from new powerplants. The proposed rule—which does not apply to existing powerplants or plants that already have been permitted and will break ground within the next 12 months—would require power-generating units to limit emissions of carbon dioxide to 1,000 pounds per megawatt. Currently, there are no limitations on how much carbon dioxide can be emitted by powerplants. EPA Administrator Lisa Jackson
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.