Renewable energy is on a roll. In 2017, global new investment in renewable power and fuels was twice that in fossil and nuclear power. Lithium-ion (Li-ion) batteries are on a roll, too. Global sales have been growing by more than 50 percent per year this decade. The recent progress of these technologies is remarkable, but it cannot be extrapolated indefinitely. Even as they roll on for another decade or so, their weaknesses—variable generation for renewables and limited duration for Li-ion batteries—will become increasingly apparent. Policymakers should take action now to prevent these limitations from stalling the fight against climate change by nurturing the next wave of energy storage technologies that go “beyond lithium.”
The present enthusiasm in the climate and energy community about systems that combine Li-ion batteries with variable renewables is understandable. These batteries can fill in gaps of up to a few hours when the sun is not shining or the wind is not blowing. This capacity allows the share of renewables on a grid to rise well above what would be feasible if cloudy days or calm nights interrupted power supplies.
However, due to inherent technological limitations, it is unlikely Li-ion batteries will ever become good enough or cheap enough to solve the problem of variability for periods of more than a few hours. If renewables are to fully displace carbon-emitting fossil fuels, electricity systems will need technologies that provide affordable, reliable long-duration storage at grid scale.
This report begins by laying out this “baseload challenge” and the importance it holds for mitigating the worst effects of climate change. It then briefly explores some of the most promising technologies that may meet this challenge. It concludes by offering recommendations to federal policymakers in the following areas:
- Adopt simple, high-profile goals for affordable, safe, long-duration grid storage system development.
Research and development (R&D):
- Set up an innovation hub to pursue a broad field of science and technology other than batteries for long-duration grid storage.
- Expand investment by the Advanced Research Projects Agency-Energy’ (ARPA-E) in long-duration grid storage R&D.
- Expand investments by the applied energy offices of the Department of Energy (DOE) in grid storage R&D and focus them on long-duration problems.
- Establish a working group on long-duration grid storage within the National Science and Technology Council (NSTC).
- Lead a new challenge on long-duration grid storage within Mission Innovation (MI).
- Expand DOE funding for long-duration grid storage technology demonstration projects, in partnership with lead users.
- Sustain Department of Defense (DOD) support of demonstration projects, at its facilities, that are consistent with its mission.
- Assist leading states that coinvest with lead users in demonstration projects.
- Ensure pathways from R&D to demonstration involving public and private partners exist for all promising technologies.
- Continue to foster and simplify partnerships between DOE national laboratories and technology development companies.
- Explore whether loan guarantees would assist long-duration grid storage technologies in achieving commercial viability.
- Create a tax incentive system that supports emerging technologies for long-duration grid storage.
- Consider regulatory and market reforms to optimize the value of existing pumped-hydropower storage resources.
- Implement an expedited process for licensing of closed-loop pumped-hydropower storage systems.
- Expand the collaborative work of planning for the fully decarbonized grid of the future.