Earlier this year, Ellen Williams, the director of ARPA-E, the U.S. Department of Energy’s advanced research program for alternative energy, made headlines when she told the Guardian newspaper that “We have reached some holy grails in batteries.”
Despite very promising results from the 75-odd energy-storage research projects that ARPA-E funds, however, the grail of compact, low-cost energy storage remains elusive.
A number of startups are closer to producing devices that are economical, safe, compact, and energy-dense enough to store energy at a cost of less than $100 a kilowatt-hour. Energy storage at that price would have a galvanic effect, overcoming the problem of powering a 24/7 grid with renewable energy that’s available only when the wind blows or the sun shines, and making electric vehicles lighter and less expensive.