A new study from the North American Electric Reliability Corp., the U.S. electric-utility watchdog group, finds that the nation’s increasing reliance on renewable-energy power sources will require policymakers to clear the way for updating the nation’s transmissions system. NERC says adding high levels of wind, solar and ocean energy, deemed “variable generation” for their intermittent characteristics, will require “significant transmission additions and reinforcements” to ensure grid reliability. NERC projects that more than 145,000 MW of new variable resources will be added to the country’s bulk power system with-in 10 years. Denise Bode, CEO of American Wind Energy Association ,praises NERC’s
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.