How clean is battery storage?
Cleaner from the start. A grid battery pays back the carbon from its manufacture in about 15 months on today's Westchester grid, then spends the rest of a twenty-year life keeping gas peaker plants switched off. Even the harshest assumptions put the payback under six years.
What happens over twenty years?
Follow a 20 MWh battery, the size of the one approved in Tarrytown, through its working life. Watch it run, drag the slider to any year, then change where its charging power comes from.
Year 20
Retired and recycled
The bond pays for removal, the site is restored, and the cells go to a recycler that recovers materials such as lithium and copper.
Capacity
Net carbon, tons of CO2
Pays back its manufacturing carbon in
15 months
Charged from today's NYC and Westchester grid
Capacity this year
92.5%
of its rated size, with top-ups
Delivered so far
140,536 MWh
A year of electricity for about 20,500 New York homes
Carbon so far
15,837 tons of CO2 avoided so far, after paying back its manufacturing
How we worked this out
- The battery: 20 MWh, one full charge and discharge a day, returning 85 percent of the power it takes in (NREL's standard assumption).
- Fading and top-ups: capacity falls about 1.5 percent a year, the figure EIA's cost study uses, and new modules restore it. We show a top-up every five years to keep the chart readable.
- Manufacturing: 55 kg of CO2 per kWh of LFP battery, from a 2023 peer-reviewed study that matches NREL's 2024 review (54 kg for batteries made in China). The higher option, 109 kg, is an older study that assumed a coal-heavy factory grid. Both cover the battery itself; the higher one also stands in for inverters and enclosures, which add to the total.
- What it replaces: each MWh it delivers is one a gas peaker plant does not have to make. A peaker emits about 584 kg of CO2 per MWh (EIA's 2024 heat rate for gas turbines, 10,999 Btu per kWh, times EPA's 53.06 kg of CO2 per million Btu). That counts only the smokestack, so it understates the benefit.
- What charges it: NYC and Westchester grid 864.5 lb of CO2 per MWh, New York average 465.1, and the worst case uses the grid's non-baseload rate of 976.9 (EPA eGRID 2023). Solar is 43 g per kWh over its full life (NREL). Because it takes in 1.18 MWh for every 1 MWh it gives back, charging emissions are scaled up by that amount.
- Homes: the average New York household uses 571 kWh a month (EIA, 2024).
What is inside a grid battery?
Almost every new grid battery now uses lithium iron phosphate, or LFP. It avoids the two metals behind the worst mining problems, and it is harder to set off.
| LFP, used in new grid batteries | NMC, the older type | |
|---|---|---|
| Cobalt or nickel | None | Both |
| Temperature where a cell can start to overheat, same lab test | 437°C | 372°C |
| Share of new grid storage worldwide, 2025 | Over 90% | Under 10% |
| Used at Moss Landing, California | No | Yes |
Lithium itself still has to be mined, with real water and land impacts. LFP's advantage is avoiding the cobalt and nickel supply chains, where the most serious documented harms are concentrated.
Whose air gets cleaner?
The plants a battery replaces are peakers: gas units that switch on during the hottest, busiest hours, often in dense neighborhoods. A battery gives power back with nothing coming out of a smokestack.
NYC peakers, high-ozone days
Up to 94%
of the city's nitrogen oxide emissions on the worst smog days
New Yorkers within a mile
750,000
78 percent of them in low-income communities or communities of color
Average US peaker
32.3 lb
of nitrogen oxides and 1.4 lb of fine particles for every MWh it makes
A battery, where it sits
0 lb
It burns nothing on site. The emissions from its charging power are counted in the chart above.
What happens when it retires?
Removal is funded before it is built
New York's model law asks battery owners to keep a bond or fund, for the whole life of the site, that pays the town to remove the equipment. Fossil plants in many markets carry no such requirement.
Recycling plants are still running
Redwood Materials says it takes in over 20 GWh of lithium batteries a year and recovers more than 95 percent of the key materials. When an early recycler, Ascend Elements, went bankrupt in 2026, its Georgia plant was bought and is now producing lithium again. Glencore bought Li-Cycle's plants and says it plans to finish the Rochester hub.
The rules need to catch up
New York's battery recycling law does not yet cover grid batteries. A national EPA rule for lithium battery recycling has not been proposed. In September 2026 the US House passed the BRACE Act, which would direct EPA to write one within 18 months; it now sits with a Senate committee. LFP holds less valuable metal than older batteries, so these rules matter.
Sources
- NREL, Annual Technology Baseline 2025, utility-scale battery storage (85% round-trip efficiency). nlr.gov
- EIA and Sargent & Lundy, capital cost report for AEO2025 (1.5% yearly fade with augmentation, about 20-year life). eia.gov
- Llamas-Orozco et al., PNAS Nexus, 2023 (LFP, 55 kg CO2e per kWh). oup.com
- NREL/TP-5400-89174, December 2024, battery carbon intensity review. nlr.gov
- Hao et al., Sustainability, 2017 (higher, China-grid estimate). mdpi.com
- EIA Electric Power Annual, Table 8.2 (gas turbine heat rate, 2024). eia.gov
- EPA, GHG Emission Factors Hub, January 2025. epa.gov
- EPA, eGRID2023 summary tables (June 2025). epa.gov
- NREL, Life Cycle Greenhouse Gas Emissions from Electricity Generation, 2021 update. nlr.gov
- ScienceDirect, thermal runaway in NMC-811 and LFP cells, 2023. sciencedirect.com
- IEA, Global EV Outlook 2026: LFP was over 90% of stationary storage installed in 2025. iea.org
- PEAK Coalition, "Dirty Energy, Big Money," May 2020. cleanegroup.org · Clean Energy Group, peaker plant data. cleanegroup.org
- NYSERDA, Battery Energy Storage System Guidebook and Model Law, February 2026. nyserda.ny.gov
- Resources for the Future, "Decommissioning US Power Plants." rff.org
- Redwood Materials. redwoodmaterials.com · Battery-News on R3 Lithium, September 2026. battery-news.de · Glencore on Li-Cycle. glencore.com
- NYSDEC, Rechargeable Battery Recycling. dec.ny.gov · Waste Dive on the BRACE Act. wastedive.com · Resource Recycling on the BRACE Act, 24 September 2026. resource-recycling.com · Energy-Storage.News on Redwood and Ascend, April 2026. energy-storage.news
Notes for reviewers
- Correction to the first draft: PNNL's "30 percent every 10 years" is a refurbishment of the power electronics, not a battery replacement. The fading and top-up figures now come from EIA's cost study.
- The manufacturing figures cover the battery pack. Whole-system studies put inverters, enclosures and cooling at 32 to 58 percent of the total; the higher toggle roughly covers that. Even the harshest combination, the older estimate with worst-case charging, pays back in about five and a half years.
- The peaker figure uses the full-load test heat rate. Real peakers often run at part load and burn more fuel per MWh, so the benefit shown is on the low side.
- The solar figure (43 g) was confirmed through two citations of NREL's table; worth checking the PDF by eye.
- Recycling news moves quickly. Rechecked 29 September 2026: Redwood reported about 20 GWh a year in April 2026; Ascend's Georgia plant is producing again under R3 Lithium; the BRACE Act passed the House on 15 September and was referred to the Senate Environment and Public Works Committee on 16 September.
- eGRID2023 is still EPA's latest grid emissions release as of 29 September 2026. When eGRID2024 comes out, the charging figures need a rebuild.
- PEAK Coalition's figures are from 2020 and cover New York City. We did not find Westchester-specific peaker data.