For the U.S. to reach its climate goals, the deadline forconstructing the last gas-fired power plant is coming up shortly — if notalready past — according to a March 30 report by the Center for SustainableEnergy.

Gas has a significant near-term role in reducing dependenceon coal-fired power and helping the transition to intermittent renewablesources, said the lead author, said Steve Weissman, senior policy adviser forthe clean energy group. But to reduce greenhouse gas emissions toa target of 80% below 1990 levels by 2050, the nation must ultimately eliminatealmost all use of fossil fuels, including natural gas, he said.

Power plants have long life cycles, so tapering future gasuse requires significant planning, noted the paper, titled "Natural Gas asa Bridge Fuel: Measuring the Bridge."

"A power plant on the drawing boards today could stillbe operational in 2050 and well beyond. With each passing year, the likely lifespan of new natural gas power plants moves further beyond 2050," accordingto the paper.

Weissman contended that the U.S. EPA's Clean Power Planmight do more harm than good because substituting gas-fired power for coalcapacity is one of the options for complying with the rules requirements. Rather,lawmakers should consider setting a final date beyond which no new natural gaspower plants can be approved, Weissman advised.

To make that possible while maintaining grid reliability,policymakers would haveto require strategic adoption of renewable power, trying to match the types andlocations for maximum impact, the paper argued. Lawmakers and regulators wouldalso need to deploy a wide range of demand-response tools, focus on energyefficiency measures and better structure regional power markets to manageshifting demand, the report added.

Almost 237 GW of gas-fired generation capacity was addedbetween 2000 and 2010, making up 81% of all the generation capacity added inthat decade, Weissman said. This momentum could increasingly complicate effortsto cut back on gas use, he said.

"As more people and institutions invest in natural gas,political pressure to sustain its use grows. It will become more and moredifficult to achieve long-range greenhouse gas reduction goals," Weissmansaid. "Natural gas cannot play a long-term role in creating our desiredcarbon-constrained future, as its benefits are not enough to support our carbonreduction goals."