The atmosphere has definitely changed in favor of some form of regulation of greenhouse-gas emissions in the U.S. since the Democrats took control of Congress and the Presidency last November. On June 26, the House passed the American Clean Energy and Security Act of 2009 (H.R. 2454) by seven votes, and Senators Barbara Boxer (D-Calif.) and John Kerry (D-Mass.) on Sept. 30 introduced a Senate version that is even stronger. Related Links: For First Time, EPA May Regulate CO2 Against this backdrop is a proposal by the Obama administration and the Environmental Protection Agency to regulate the gases from coal-fired
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.