Without solid commitments from potential customers and the emergence of North American shale gas as a price-competitive energy source, the proposed $35-billion Denali pipeline in Alaska, owned by subsidiaries of BP and ConocoPhillips, has called it quits. Backers abandoned Denali, but TransCanada line's backers say they'll push forward. “As far as Denali is concerned, we are finished,” says Scott Jepsen, vice president of business services for Denali – The Alaska Gas Pipeline LLC. “The focus of Denali has always been to move natural gas from the North Slope. Our work here is over."Denali will also withdraw its Federal Energy Regulatory
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.