How to Make a Cheap Battery for Storing Solar Power | MIT Technology Review
Whitacre’s batteries are expected to last twice as long as lead-acid
batteries and cost about the same to make. They won’t require
air-conditioning and will use nontoxic materials. Electrical current in
the battery is generated as sodium ions from a saltwater electrolyte
shuttle between manganese oxide–based positive electrodes and
carbon-based negative ones.
One place the battery could make a big
difference: in poor regions of the world that lack an existing electric
grid. By 2030, one billion people are expected to get electricity for
the first time. That will mean a lot more use of fossil fuels unless
renewable power options are as cheap, safe, and reliable as possible. If
“even a fraction of that billion can use solar because of our
batteries,” Whitacre says, the company will be able to reduce not only
carbon dioxide emissions but also local pollution from diesel
generators.
To match the cost of lead-acid batteries, which are
among the cheapest types, Whitacre uses inexpensive manufacturing
equipment repurposed from the food and pharmaceutical industries.
Hydraulic presses originally designed to make aspirin pills stamp out
wafers of positive and negative electrode materials, and robot arms
built to wrap chocolates are used to package electrode wafers with foils
that act as current collectors. At the end of the line, the
briefcase-sized batteries are stacked and bolted together. A pallet of
84 batteries, about a meter tall, will store 19.2 kilowatt-hours of
electricity. Whitacre says you’d need about 60 such pallets to serve a
village of 200 people in a poor country. Two pallets would power a U.S.
home for a day.
The technology has its limits. It is best suited
for slow and steady operation, not rapidly charging and discharging
large amounts of power as some utilities require. And while the
batteries are cheaper than other kinds, pairing them with solar panels
still can’t beat the economics of conventional power plants in most
areas. That is why Whitacre is focusing initially on regions without an
existing electricity grid. Aquion has already started shipping batteries
to customers for evaluation. The company expects to start full-scale
production by this spring, making enough batteries each year to store
about 200 megawatt-hours of electricity—enough for roughly 150
solar-powered villages. The factory in Pennsylvania could be replicated
in other countries. “If our technology proves out, we won’t be able to
make them fast enough,” Whitacre says.
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