The U.S. Energy Dept. is soon to give Chicago-based energy services provider Exelon Corp. "reasonable assurance" of a $50-million agency loan guarantee to spur construction of what would be the nation�s largest urban solar powerplant, says an Exelon spokesman. Development of the 10-MW photovoltaic facility at a former industrial site on Chicago�s South Side, to be finished by the end of 2009, is contingent on receiving the loan guarantee for 80% of its $60-million cost, says the spokesman. Exelon and its partner, San Jose, Calif.-based SunPower, have begun clearing the 39-acre brownfield site where the plant would be built. SunPower
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.