- Different energy storage technologies can make optimal use of rising levels of intermittent renewable energy, with the combined resources replacing fossil-fueled generation systems by mid-century, according to an MIT report published on May 12.
- The Future of Energy Storage by the MIT Energy Initiative, or MITEI, provides a blueprint for supporting and using grid storage technologies — existing and emerging — to affordably slash emissions. The nearly 400-page study looks at the Northeast, Southeast and Texas, which reflect different demand portfolios and levels of wind and solar.
- The report also assesses the potential for storage matched with renewables to replace coal power in India and other countries. As grid storage rises, “policies must be adjusted to avoid excess and inequitable burdens on consumers, to encourage electrification for economy-wide decarbonization, and to enable robust economic growth, particularly in emerging market developing economy countries,” it states.
MIT’s study, developed over three years, analyzes strategies for capitalizing on various storage technologies — electro-chemical, thermal, chemical and mechanical — that can capture variable wind and solar energy flows to decarbonize the grid by 2050.
Enabling a climate-friendly grid in the U.S. requires changes in planning and operational tools to reflect the transitioning system necessary to fight climate change, according to the report. It also calls for increasing fixed charges to make energy storage financially viable. In addition, the report recommends modifying the federal government’s current practice of granting intellectual property rights to private sector partners who share the costs of technology demonstration projects. “Public investment in technology demonstration and early deployment activity is to disseminate knowledge,” the report says.
In the past, the DOE has insisted that private sector partners share project costs as a way to “stretch” federal dollars. Because private partners are typically granted intellectual property rights in return, this practice compromises the basic objective of publicly supported technology demonstration projects, which is to spread information among all industry participants, thereby creating the conditions for efficient competition. Federal demonstration projects should include explicit requirements for information sharing with other U.S. entities that have not been partners, even if this requires a greater federal contribution.
Excess solar and wind energy output can be stored and fuel the grid at times of high demand, “maintaining reliability in a cost-effective manner — that in turn can support the electrification of many end-use activities beyond the electricity sector,” MITEI Director Robert Armstrong, professor of Chemical Engineering, said at the report’s release.
Assuming costs continue to fall for wind and solar technologies, the study’s modeling “identifies cost-effective pathways for decarbonizing electricity systems — reducing emissions by 97%-99% relative to 2005 levels in the United States,” the study concludes. “Efficient decarbonization will require substantial investments in multiple energy storage technologies, as well as in transmission, clean generation, and demand flexibility,” it adds.
“It is helpful to see where and how energy storage technologies need to evolve and understand the various tradeoffs between energy or capacity costs, roundtrip efficiency [and] duration, among other things,” Jin Noh, policy director of the California Energy Storage Alliance, said of the report. He added it could guide policies around developing and commercializing various new energy storage technologies.
Today’s dominant grid storage is provided by lithium-ion batteries, which typically have a maximum output of four hours, while storage providing many more hours of power duration is needed to meet different grid demands, including weather and seasonal-related. The Department of Energy is currently working on a research goal to help lower the cost of 10-hour plus energy storage. It recently approved $505 million to advance multi-hour storage paired with renewables.
The MIT report calls for more support of longer duration, in particular, electro-chemical storage technologies that use widely available earth materials, including those derived from second-use batteries and recycling.
More government financial aid for storage with at least 12 hours of output is needed because it is not backed by substantial private investment, like lithium-ion batteries, according to the report. Private financing for these energy-dense, low-cost batteries in electric vehicles “has significantly improved prospects for short-duration electricity system storage,” the report points out.
Another challenge is that long-duration storage will have a low value when wind and solar production drops, the report says. Thus, because of the very different characteristics and values of intermittent energy, MIT also calls for higher fixed charges to ensure storage technologies reap a profit.
“Our modeling shows that decarbonized systems in which wind and solar generation play a dominant role will have zero or low marginal system costs of energy during many hours,” in contrast to dispatchable generation using fossil fuels, Howard Gruenspecht, MIT senior energy economist, said. Because “future decarbonized systems are likely to have high capital costs and very low variable costs, fixed charges should play a larger role in cost recovery than they do presently” he added. That includes basing charges on consumers’ income level “to address equity as well as efficiency.”