It’s too early to say whether the Department of Energy’s ARPA-E agency has hit a technological home run, but the research it funds is worth tracking closely.

ARPA-E yesterday announced $130 million for 66 grants that have the potential for “transformational” change in energy. There are indeed some bold ideas on the list, such as wind turbines made of cloth and an underwater oscillating wing that gets energy from tides and rivers. In a shift this year, many projects are focused on using the plentiful natural gas in U.S. (See full list here and Kevin Bullis’ choice of stand-out projects here).

But like previous grant programs, energy storage is high on ARPA-E priority list, with about 20 projects being funding in this area, some as low as half a million dollars. The company which received the largest grant is PolyPlus Battery Company, which was also awarded $9 million this summer from the DOE’s Advanced Manufacturing Office. The ARPA-E money, which is for both PolyPlus Battery and Johnson Controls, is to develop an aqueous rechargeable lithium-sulfur battery which promises better energy density that today’s lithium ion batteries.

“The key word there is aqueous,” says research associate Thomas Conry at PolyPlus Battery. “Over the past 30 years, traditional non-aqueous Li-S batteries have been stuck in the lab, unable to transition to commercial reality. PolyPlus has had breakthroughs in the chemistry that solve many of the hurdles.”

The company is first developing a lithium seawater battery and rechargeable lithium air batteries. Key to all its planned batteries is a ceramic membrane that is impervious to water and allows lithium ions to move through. The manufacturing grant is focused on methods for producing that and other components at scale, Conry says. (See, Got a Battery Breakthrough? You Need Friends in Manufacturing.)

Another company, Vorbeck Materials, received a $1.5 million grant for a lithium sulfur battery that would improve the energy density and charge time of today’s batteries. Sharp Laboratories of America, meanwhile, got $2.9 million for a sodium ion battery it hopes will dramatically lower the cost of grid storage. 

There were also grants awarded for fuel cells, flow batteries, and thermal storage research. NREL, for example, received a grant to develop a system to convert heat from concentrated sunlight to electricity using thermoelectric materials. Typically, ARPA-E projects, which are high-risk, aim to produce a prototype within two or three years, with the hope a product can then be commercialized.

It’s well known that innovations in energy storage and batteries take years (See, Toyota Plugs Away at the Next-Gen Electric-Car Battery). And as most energy entrepreneurs will tell you, receiving venture capital seed funding for anything related to new types of energy storage is a difficult proposition given the long development times and costs. In that sense, ARPA-E’s grant money—one of few government energy programs that generally enjoys bipartisan support—is vital for exploring which storage technologies have the potential to succeed today’s products.