The Denali project is estimating it will cost $35 billion to build a treatment plant and major line to move natural gas from Alaska's North Slope to market.

Denali is a joint effort of ConocoPhillips and BP. It is competing with another major line being advanced by TransCanada Corp. and Exxon Mobil Corp.

The TransCanada project has estimated its project's cost at $20 billion to $41 billion, depending on the route. The company plans to start courting gas producers and seeking shipping commitments as early as May 1.

Both projects hope to be in service around 2020.

Denali announced the new details Wednesday.