New Grid Storage Technology Helps Integrate Renewables

New Grid Storage Technology Helps Integrate Renewables

(MIT Technology Review) Duke Energy installs batteries, ultracapacitors to cover power shortages and store energy for peak demand.

Developing cheap energy storage is a critical step in moving to renewables and away from fossil fuels as the primary source of electricity: it’s the only way such intermittent sources can supply power to the grid when the wind’s not blowing and the sun’s not shining.

Duke Energy, the nation’s largest utility, is trying a novel strategy to tackle this challenge. At its Rankin substation, in North Carolina , it has installed a system of hybrid energy storage that combines a battery from Aquion Energy and ultracapacitors from Maxwell Technologies .

The two technologies are complementary. The ultracapacitors, which are good for large, short-duration power surges, help supply power when the solar power on the grid fluctuates because of cloud cover. The Aquion batteries, which are better for storing energy over longer periods, can supply power later in the day, when the sun goes down and electricity demand rises. Combining the two using smart electronics enables the system to efficiently handle power demand over periods ranging from seconds to several hours. The system is the first of its kind at utility scale, says Thomas Golden, technology development manager for Duke. Combining ultracapacitors and batteries offers a low-cost, highly flexible grid storage system. “A hybrid system that uses ultracapacitors for the higher-power needs and lower-cost battery options, such as Aquion’s technology, has the potential to provide a more economical solution when compared to each of the technologies put to use separately—or any other solution, for that matter,” says Apurba Sakti, a research scientist with the MIT Energy Initiative who works on advanced energy storage technologies.

North Carolina ranks fourth among the states for installed solar capacity, and Duke is investing half a billion dollars to expand its solar generation there. The area served by the Rankin substation includes a 1.2-megawatt solar installation just one mile away. The hybrid energy storage system, which began operation in February, includes a battery from Aquion that is well suited for this kind of grid solution. Aquion’s batteries use a saltwater chemistry that can […]

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