WIRED IN
Perspectives on electricity
Getting the Best Charge from
Batteries
With almost 10 battery projects underway, Duke Energy has
invested a lot in the future of energy storage and the 21st century
electric grid. The quick verdict: We remain bullish on the prospects
for storage, but know there’s plenty of work to do.
Our efforts vary in size and chemistry. In Notrees, Texas, our
36-megawatt advanced lead acid battery is part of a pilot in the
Electric Reliability Council of Texas (ERCOT) region, shaping the
ancillary service market using a fast-responding resource. The installation is next to one of Duke Energy’s wind farms.
On a smaller scale, we linked a solar array, lithium-titanate battery
storage unit, and electric vehicle (EV) charging stations at the Clay
Terrace Shopping Mall in Carmel, Indiana, to demonstrate a sustainable microgrid that can be used by the mall to attract additional
business by offering free EV charging.
Energy storage hardware deployed on the grid has improved, costs
are coming down, energy densities are improving, and the cycle life
of systems is increasing. Technologies that were once limited to lead
acid and lithium chemistries are now expanding, and pilot projects
are coming on-line for technologies such as long-duration flow
batteries and rechargeable metal-air systems.
But even the best battery is only as valuable as the benefits it
brings to the grid. To date, much of the work in energy storage has
focused on hardware. The other side of the equation—how to create
value on the grid—is just beginning to be addressed.
At Duke Energy, we are focused not so much on finding the next
great battery, but creating the best value for the grid and our customers. Better yet, how do we make energy storage tackle a number
of tasks for the grid—instead of being limited to a single area?
At our McAlpine Energy Storage System in Charlotte, North
Carolina, we deployed an islandable microgrid tied to a 24-kV
distribution circuit. It is demonstrating how a utility-owned distribution asset can support the grid by integrating renewable generation while providing higher reliability to a city fire station—all using
common utility assets.
What Does the Future Look Like?
While work continues on the multi-use of energy storage in transmission and distribution, the biggest breakthroughs might be seen
in smaller, distributed batteries.
Zak Kuznar
Technology Development Manager
Duke Energy
Residential or community energy storage units deployed today
typically provide backup power or shift energy from peak to offpeak to reduce demand charges.
The cost of such systems can result in a tough business case to
make for home and business owners who lose power infrequently.
And it also doesn’t come close to realizing the untapped potential of
the technology located on the customer’s premises.
But imagine thousands of such units controlled by the utility—
shifting energy from off-peak to peak times during hot summer
days, smoothing out solar generation’s variable output, and reserving
capacity to provide backup power to critical loads during a grid
outage.
This creates value for both the grid and customers—and creates
new, innovative business models of behind-the-meter ownership.
This “stacking of value streams” benefits customers and the electric grid. While we need to address the technological gaps that
remain, such thinking can ultimately prepare and equip utilities to
incorporate diverse energy storage configurations into our business
models.
These are just a few of the possibilities for battery storage. When
we combine what we are learning today with new developments in
hardware and creative thinking elsewhere, we can see energy storage
providing a welcome charge to the utility industry.