Sen. Susan Collins introduced a bipartisan bill Wednesday to bolster energy storage, an emerging technology geared at solving renewable energy’s most persistent problem: using it when the sun isn't shining or the wind isn't blowing.

The focus on energy storage fits squarely into Republicans' 'innovation agenda' for combating climate change, promoting private sector innovation, with federal government help, as an alternative to regulation, taxes, or mandates.

“Next-generation energy storage devices will help enhance the efficiency and reliability of our electric grid, reduce energy costs, and promote the adoption of renewable resources,” said Collins, R-Maine. “Our bipartisan legislation would help catalyze the development of this technology that holds great promise in the fight against climate change by supporting clean energy generation, including wind and solar.”

Collins and the other Republicans backing the bill, Sens. Cory Gardner of Colorado and Martha McSally of Arizona, face tough reelection fights in purple states in 2020, with environmental issues expected to play a prominent role.

[Previous coverage: Republicans warm up to climate change]

Other co-sponsors of the bill include Sens. Martin Heinrich, D-N.M., Tina Smith, D-Minn., Chris Coons, D-Del., and Angus King, I-Maine.

The Better Energy Storage Technology Act or “BEST Act” directs the Energy Department to establish a research, development, and demonstration program for grid-scale energy storage.

It authorizes $300 million over five years for the Energy Department to partner with the private sector on building at least five grid-scale energy storage demonstration projects by September 2023 that can provide power to the grid for 10 to 100 hours and operate for 20 years.

Jason Burwen, vice president of policy at the Energy Storage Association, said the goal of the bill is to prove the viability and cost-effectiveness of next-generation energy storage technologies at the demonstration level, to set the table for commercialization.

One of the biggest impediments to greater use of grid-scale energy storage is cost. The bill aims to increase the affordability of storage by directing the Energy Department to pursue a strategic plan and implement a cost target for the demonstration projects.

Backers of the bill compare its potential impact to the Energy Department’s SunShot Initiative that decreased cost of solar power by 75%.

“A lot of folks around the industry see storage as being where solar was 10 years ago where it has a technology hump to get over,” said Brandon Audap, vice president of government relations for the conservative group Citizens for Responsible Energy Solutions, which supports the bill. “We have seen this work before, where solid government investment and public private partnerships could give an industry on the cusp the boost it needs to take the next step.”

Energy storage is not a power source. Rather, a battery or other energy storage resource carries excess energy that can be used when the sun sets and demand peaks later in the day.

While storage is primarily identified for its ability to increase the use of renewables, it can capture excess energy for any fuel source. It also benefits the entire grid by balancing supply and demand instantaneously, lowering costs for consumers by helping to avoid “peak demand.”

The consulting group Wood MacKenzie projected last month the global market for energy storage will rise thirteenfold by 2024, with the United States and China set to dominate the market, expected to represent 54% of deployed capacity by that year.

“There is a not just a bipartisan interest, but almost a bipartisan hunger to move the ball forward on energy storage because of the widespread recognition for how valuable it is for the flexibility of the grid, and because storage works for everything,” Burwen said.

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The Trump administration’s Energy Department has become a vocal proponent of energy storage as part of its push to improve what Secretary Rick Perry refers to as grid resilience, with the backup power from storage enabling the grid to recover faster after power outages.

There are other bipartisan initiatives in Congress to enhance energy storage. Collins is the lead Republican sponsor of another bill introduced Wednesday called the “Promoting Grid Storage Act,” which is meant to help states and localities improve the integration of storage on the grid into long-term planning.

Gardner has co-sponsored a bill to make storage eligible for the investment tax credit — incentives that have helped lower the cost of wind and solar. Rep. Vern Buchanan, R-Fla., this week signed on to co-sponsor the House version of that bill.