Important advances in energy storage

Ivan Penn writes in the New York Times about the use of zinc batteries for energy storage. Making the batteries rechargeable and lowering their cost are seen as important advances in enabling the electric grid to depend on power from renewable sources.

 

How Zinc Batteries Could Change Energy Storage

Over the past six years, 110 villages in Africa and Asia received their power from solar panels and batteries that use zinc and oxygen. The batteries are the basis of an innovative energy storage system created by NantEnergy, a company owned by Patrick Soon-Shiong, a biotech entrepreneur and surgeon originally from South Africa.

Thomas Edison tried to develop batteries made with zinc 100 years ago. But he did not figure out how to make them technologically viable. NantEnergy says its zinc air batteries are the first to become commercially available.

Scientists at NantEnergy said they had achieved two key goals: to make the batteries rechargeable, and to lower their cost for energy storage to $100 per kilowatt-hour. That is a figure that some people in the industry have said is essential to creating a carbon-free electric grid that operates even when the sun is down and the wind abates.

Zinc air batteries are one of several potential alternatives to lithium-ion batteries, which have been the focus until now for large-scale power storage and electric vehicles.

What are the commercial sources of zinc?

Dr. Soon-Shiong, whose company gets its zinc from Indonesia, has cited the mineral’s abundance. The United States accounts for about 5 percent of the world’s zinc reserves and 7 percent of production, mostly from mines in Alaska, according to Sri R. Narayan, professor of chemistry at the University of Southern California. Australia and China have about half the world’s reserves and are among the largest producers.

Dr. Narayan said reserves of lithium, a primary element in lithium-ion batteries, were one-twentieth those of zinc, but he added a note of caution. “At the present rate of production of zinc, zinc reserves will last about 25 years,” he said. “So it is not clear from the reserves available if we will have enough zinc to support the enormous need that will result from the demand for grid-scale batteries.”

Materials like lithium are costly in part because they are rare. The mining of lithium has also threatened the health and safety of workers in areas where it has been plentiful, like the Democratic Republic of Congo. Prolonged exposure to lithium has been associated with health effects like fluid buildup in the lungs. And lithium-ion batteries can pose a fire hazard.

Zinc air batteries lack toxic compounds, are not flammable and can be disposed of safely, according to MIT Technology Review. Still, the mining and processing of zinc does present hazards. It comes from an ore consisting of zinc sulfide and is usually produced in conjunction with lead, cadmium and nickel, Dr. Narayan said, and large-scale production can raise environmental issues from sulfur dioxide and cadmium-vapor release.

What does energy storage with zinc air batteries cost?

Dan Reicher, an assistant secretary of energy in the Clinton administration, cautioned that a battery’s cost per kilowatt-hour depended on the application and scale, making useful comparisons difficult.

NantEnergy said that at $100 per kilowatt-hour, the cost of zinc air batteries compared favorably with that of lithium-ion batteries, which can be $250 per kilowatt-hour but are more typically $300 to $400, according to Yogi Goswami, distinguished university professor and director of the Clean Energy Center at the University of South Florida.

Even at $100 per kilowatt-hour, energy storage remains a significant expense for the utility industry, although batteries have been declining precipitously in price and are expected to become as common as residential solar panels in the next few years.

Will the batteries be available for homes or mobile devices?

NantEnergy said that its immediate focus was on delivering its product for microgrids — self-contained solar-power arrays serving small areas — rather than on individual residential customers or utility-scale systems. But the company anticipates supplying the batteries for home use in the future, in California and New York at first.

Villages and islands using the batteries — in packs the size of briefcases — typically connect them to solar arrays the size of the kind of canopy that might be found over a parking lot or at a school. In addition, the batteries provide power to hundreds of communications towers, a significant part of NantEnergy’s business. For the next version of the product, the company plans to add transportation systems like electric cars, buses, trains and scooters.

And beyond that? “We have a first prototype of a mobile radio,” Dr. Soon-Shiong said. “We don’t want to overpromise, but the energy density of our battery makes it really possible.”

“We will be turning our attention to this market,” he added. “It’s huge, but probably 2020 for us.”

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