Eighteen battery storage projects totaling more than 1,650 megawatts are proposed across Long Island. They’ve been proposed to help meet New York State’s six-gigawatt energy storage goal, a program the state says will store renewable generation “for the times it is needed most,” firming intermittent solar and wind into steady power.

That belief that batteries store renewable energy is the basis for nearly everything that follows. It’s the basis for a statewide subsidy program modeled on renewable energy credits, whose costs are allocated across the utilities, LIPA included. It’s the basis for the 15-year property tax exemption the legislature wrote for solar and wind, and for the federal government’s “Clean Electricity Investment Credit.” And it’s the pitch developers bring to town boards from Islip to Mastic.

None of those benefits, state or federal, is conditioned on where the electricity actually comes from. So it’s worth asking the question the incentives never ask: when these batteries charge, what generates the power going into them?

On Long Island, the answer, overwhelmingly, is natural gas, 91% of the time (according to NYISO’s own marginal-emissions data). Not just now, but likely for the lifetime of these projects: our modeling finds New York would need five to nine times all the solar it has ever built before charging windows are even half renewable.

Zone-by-zone breakdown

Every battery on the map charges from the same place: the grid of the zone it sits in. Batteries earn their money by buying power when it’s cheapest and selling it back when it’s expensive, so we pulled a full year of NYISO real-time price data and found the four cheapest hours of every single day in every zone. Those are the hours a battery operator charges. Then we asked what was actually setting the price in those hours, because on a power grid, new demand isn’t served by the average of everything running. It’s served by whatever plant ramps up next. At two in the morning, that is not solar.

The chart below shows the answer for each zone, hour by hour across 365 days: the share of charging hours where gas plants set the price, the share where zero-carbon resources did (hydro, wind, nuclear surplus), and the share too close to call, which we count against our own case. And you don’t have to take our word for the method. NYISO, the grid operator, publishes its own measure of exactly this, the marginal emission rate, which it says is “[r]elevant for near-term consumption decisions” like charging. Each zone’s bar carries NYISO’s number alongside ours. The two agree within a few points everywhere.

What they told you

Designed as a zero-emission energy source, the Project will play a critical role in advancing New York State’s clean energy objectives under the Climate Leadership and Community Protection Act (CLCPA) and the State Energy Plan.

AES, Developer, Horseblock Energy Storage System (Medford, Brookhaven) — NYSERDA ISCRFP25-1 Attachment B Public Project Summary (subsidy application), December 11, 2025

CCE applauds LIPA for approving the contracts for two Battery Energy Storage Systems, which will assist our critical transition away from dirty, polluting peaking plants while creating a more resilient energy grid and delivering renewable power to Long Island homes.

Adrienne Esposito, Executive Director, Citizens Campaign for the Environment — LIPA press release, December 18, 2024

Everybody knows or speaks to a lot of the renewable energy benefits, because this is designed to sustain and promote the deployment of renewable energy sources, which presumably will make the environment cleaner and improve quality of life.

Steven Losquadro, Attorney for Rhynland Energy (Edwards Calverton project, Riverhead) — RiverheadLOCAL (Denise Civiletti), reporting the Riverhead Planning Board review, April 21, 2025

Integrating storage in the electric grid, especially in areas with high energy demand, will allow clean energy to be available when and where it is most needed.

John Rhodes, Acting CEO, Long Island Power Authority — LIPA press release announcing the KCE contracts, December 18, 2024

Key Capture Energy is excited to partner with LIPA to bring these projects online and support a clean and reliable electric grid across Long Island.

Brian Hayes, CEO, Key Capture Energy — KCE press release, December 18, 2024

Methodology

NYISO real-time zonal prices and fuel mix, 12 complete months, every day's 4 cheapest hours classified by what set the price; corroborated by NYISO's Implied Marginal Emission Rates (report P-72) and EPA CAMD plant-level hourly data. Confirmed-gas figures are floors; ceilings including ambiguous hours are shown on the map. Zero-carbon charging hours are real, counted, and disclosed on every project marker.

Come make sense of the grid with us

Everything comes down to how the electric grid actually works. On Thursday, August 20, we're bringing Meredith Angwin, a.k.a. "The Electric Grandma," one of the first women to run projects at the Electric Power Research Institute, to Ulster County for a plain-English crash course: why bills are rising, how the grid keeps the lights on, and which power sources you can actually count on.

Understanding Energy: A Civic 101 Crash Course
Aug 20, 6–8 pm | M. Clifford Miller Middle School, Lake Katrine | $15

Info & Tickets