Researchers Develop a Water-based Battery to Store Solar and Wind Energy

Estimated reading time: 5 minutes

According to DOE estimates, about 70 percent of U.S. electricity is generated by coal or natural gas plants, which account for 40 percent of carbon dioxide emissions. Shifting to wind and solar generation is one way to reduce those emissions. But that creates new challenges involving the variability of the power supply. Most obviously, the sun only shines by day and, sometimes, the wind doesn’t blow. 

But another less well-understood but important form of variability comes from surges of demand on the grid – that network of high-tension wires that distribute electricity over regions and ultimately to homes. On a hot day, when people come home from work and crank up the air conditioning, utilities must have load-balancing strategies to meet peak demand: some way to boost power generation within minutes to avoid brownouts or blackouts that might otherwise bring down the grid. 

Today utilities often accomplish this by firing up on-demand or “dispatchable” power plants that may lie idle much of the day but can come online within minutes – producing quick energy but boosting carbon emissions. Some utilities have developed short-term load balancing that does not rely on fossil-fuel burning plants. The most common and cost-effective such strategy is pumped hydroelectric storage: using excess power to send water uphill, then letting it flow back down to generate energy during peak demand. However, hydroelectric storage only works in regions with adequate water and space. So to make wind and solar more useful, DOE has encouraged high-capacity batteries as an alternative. 

High capacity, low cost

Cui said there are several types of rechargeable battery technologies on the market, but it isn’t clear which approaches will meet DOE requirements and prove their practicality to the utilities, regulators and other stakeholders who maintain the nation’s electrical grid. 

For instance, Cui said rechargeable lithium ion batteries, which store the small amounts of energy needed to run phones and laptops, are based on rare materials and are thus too pricey to store power for a neighborhood or city. Cui said grid-scale storage requires a low-cost, high-capacity, rechargeable battery. The manganese-hydrogen process seems promising. 

“Other rechargeable battery technologies are easily more than five times of that cost over the life time,” Cui added. 

Chen said novel chemistry, low-cost materials and relative simplicity made the manganese-hydrogen  battery ideal for low-cost grid-scale deployment. 

“The breakthrough we report in Nature Energy has the potential to meet DOE’s grid-scale criteria,” Chen said. 

The prototype needs development work to prove itself. For one thing it uses platinum as a catalyst to spur the crucial chemical reactions at the electrode that make the recharge process efficient, and the cost of that component would be prohibitive for large-scale deployment. But Chen said the team is already working on cheaper ways to coax the manganese sulfate and water to perform the reversible electron exchange. “We have identified catalysts that could bring us below the $100-per-kilowatt-hour DOE target,” he said. 

The researchers reported doing 10,000 recharges of the prototypes, which is twice the DOE requirements, but sid it will be necessary to test the manganese-hydrogen battery under actual electric grid storage conditions in order to truly assess its lifetime performance and cost. 

Cui said he has sought to patent the process through the Stanford Office of Technology Licensing and plans to form a company to commercialize the system.

• < Previous Page