Power Connections
Bigger, Better Batteries
Storing electricity is still a challenge

IMAGE: Edd Patton

Electricity remains tricky to manage. When it’s created, it must immediately be moved to where it can be used. When it’s needed, it must be instantly on hand. Yet there’s no sure-fire way to store it, unlike water or natural gas.

Due to this “use it or lose it” factor, engineers have long sought methods to “stockpile” electricity. In recent years, the need for energy storage has grown—from supplementing renewable energy sources like wind farms to powering hybrid electric vehicles. All of this has sparked new efforts to find the better battery.

To date, large-scale battery arrays haven’t offered a good energy storage option for electric cooperatives—they’re expensive, don’t hold a charge for long and can have short life spans. But as technology improves, many experts see the “better battery” as a major breakthrough waiting to happen.

Batteries used for large-scale energy storage range from glorified lead-acid versions (what’s in your car) to more advanced nickel-cadmium batteries (such as those running a cordless drill). A recent Cooperative Research Network (CRN) study analyzed these and other battery types to find the best for co-op use.

“We looked at all of the different options out there,” explains Dale Bradshaw, a CRN consultant. “The head-and-shoulders winner, with the lowest up-front cost, longest life, acceptable efficiency and low environmental impact, appeared to be the zinc-bromide battery.”

The battery can be viewed as an electroplating machine. During charging, zinc is electroplated onto conductive electrodes, while at the same time bromine is formed. The batteries are in the development stage.

CRN plans to put zinc-bromide batteries to the test through a proposed research project with four electric co-ops. Each co-op would demonstrate how the batteries could be used in different ways, in different parts of the country.

Central Electric Power Cooperative, a generation and transmission (G&T) co-op based in Columbia, South Carolina, would use the batteries to, among other things, flood the power grid with stored energy when outages occur. The co-op could also supply electricity to the grid during times of highest electricity demand. Trimming the “peak” requirements reduces demand charges and thus avoids the need to switch on expensive natural gas-fired generators for short terms.

Seminole Electric Cooperative, a G&T based in Tampa, Florida, plans to use the batteries to store solar power. The co-op’s photovoltaic solar array typically provides the most power at noon or 1 p.m. By storing that energy at noon, the G&T can put it to use later in the day when more electricity is needed, but clouds have moved in.

Kaua’i Island Utility Cooperative and Kotzebue Electric Association, which respectively serve parts of Hawaii and Alaska, would deploy the batteries to manage the intermittency of renewable solar and wind generation. If wind energy were stored at night, that power could then be used during the day—when there’s a bigger demand for electricity but breezes may not cooperate. These far-flung co-ops could also use the batteries to ensure service reliability, feeding power to consumers when parts of the system experience outages. As a result, both co-ops will significantly reduce the use of expensive oil-fired generators during periods of high demand.

“We think this could be one of the biggest breakthroughs of the last 20 years,” Bradshaw says. “What we’re doing now could have a major impact on co-ops in the future. It’s one of the rare opportunities where we can begin to stabilize the price of electricity, hopefully slowing down increases in rates.”

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Scott Gates writes on consumer and cooperative affairs for the National Rural Electric Cooperative Association, the Arlington, Virginia-based service arm of the nation’s 900-plus consumer-owned, not-for-profit electric cooperatives.

TAGS: Technology


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