CAES a Potential Solution to California’s “Duck Curve,” Say Experts

California’s burgeoning renewable generation sector, given renewed vigor with a proposed increase in its renewables mandate, means it will need robust energy storage capacity going forward, said speakers at a session at the Electric Power Conference and Exhibition April 22 in Rosemont, Ill.

Much of that storage capacity may be provided by a mammoth combined wind–compressed air energy storage (CAES) facility under development in Utah and Wyoming.

Parag Soni, director, energy group, for Navigant Consulting, gave an outline of the Pathfinder project. It would take power from a 2.1-GW wind farm in southeastern Wyoming, where wind volumes are among the largest in the U.S. The developers are projecting a 51% capacity factor for the farm’s wind turbines.

That power would transit a 528-mile-long high-voltage direct-current transmission line to a 1.2-GW CAES plant to be built in Delta, Utah, where excess power could be stored for transmission to California via an existing 2.4-GW line.

One of the partners in the project is Burbank Water & Power (BWP), a municipal utility in the Los Angeles area. BWP is facing a welter of mandates to grow its renewable generation, but a future of flat-to-negative load growth means it cannot grow its way out of the problem, explained BWP manager Lincoln Bleveans.

BWP has limited conventional generation, which means it cannot ramp down sufficiently during future peak solar output. Drawing on time-shifted power from Pathfinder will help solve that problem.

CAES is a mature technology that has nevertheless seen only limited application. In a sense, it’s been a solution in search of a problem until recently. Bobby Bailie, business development director-CAES for Dresser Rand—which developed the only CAES plant in the U.S.—told attendees, “We’ve been waiting 23 years for the market to catch up.”

Dresser-Rand’s latest technology, which it calls SmartCAES, offers turndown capacity from 10% to 100% with a flat heat rate across that range. The system can manage less than 10 minute startup time in generation mode and can ramp 20% rated power per minute.

—Thomas W. Overton, JD is a POWER associate editor (@thomas_overton, @POWERmagazine).