What Flatiron Energy does

Flatiron Energy LLC is a private, Boulder- and Denver-based independent power producer (IPP) founded in 2021 and backed by Hull Street Energy, focused exclusively on developing, building, owning, and operating standalone utility-scale battery energy storage systems (BESS) in the Northeast and Mid-Atlantic United States. Its portfolio spans ISO-NE, NYISO, and PJM with a development and under-construction pipeline of approximately 4.5 GW / 18 GWh, including the Taft Project (200 MW / 800 MWh in Uxbridge, Massachusetts), Salt Cod (168 MW / 672 MWh), Energizar (250 MW / 1,000 MWh), and Lite Brite (300 MW / 1.2 GWh, currently paused). Projects use lithium iron phosphate (LFP) battery technology, sourced under a multi-year 7.2 GWh supply agreement with SK On covering 2026-2030, and are deployed in containerized or building-based installations ranging from 100 MW to 300 MW with 4-hour duration.

The company monetizes these assets through a combination of long-term bilateral offtake agreements with utilities, capacity auctions operated by ISO/RTOs (ISO-NE, NYISO, PJM), merchant exposure in wholesale energy and ancillary services markets, and project-level financing arrangements including debt, tax equity, and preferred equity. A $250 million corporate credit facility managed by HPS Investment Partners funds development expenses across the portfolio, and a $540 million project financing was closed in September 2025 for the Taft Project with a syndicate led by First Citizens Bank and Nord/LB. Flatiron generates revenue by displacing expensive peaker plants, providing grid reliability and capacity services, and enabling renewable energy integration in constrained Northeast grids.

The company pursues a sales-led, enterprise field sales GTM motion targeting utilities, grid operators, state energy programs, and landowners. Direct offtake negotiations and competitive procurement processes (such as Massachusetts's first large-scale energy storage tender in late 2025, where Flatiron won approximately 1.3 GW) are the primary commercial channels. The business is Certified B Corporation and operates offices in Denver (headquarters), Boulder, New York, and Boston, with a leadership team drawing on experience from ENGIE, GE, Fluence (via AMS), Con Edison, Goldman Sachs, National Grid, and other major energy firms.

Name

Flatiron Energy

Legal name

Flatiron Energy LLC

Website

https://flatiron.energy

Company type

Private

Founded year

2021

Operating status

Operating

Headcount range

51–100 employees

Short description

Flatiron Energy is a private, Hull Street Energy-backed independent power producer that develops, owns, and operates utility-scale lithium iron phosphate battery energy storage projects (100-300 MW each) serving utilities and grid operators in the Northeast and Mid-Atlantic US (ISO-NE, NYISO, PJM), with a 4.5 GW / 18 GWh development pipeline and first projects targeting commercial operation in late 2026.

Ownership category

akta.pro rank

Product category

Utility-Scale Battery Energy Storage

NAICS

Electric Power Generation (22111), Electric Power Generation, Transmission and Distribution (2211), Electric Bulk Power Transmission and Control (221121)

SIC

Cogeneration Services & Small Power Producers (4991), Electric Services (4911)

akta.pro primary industry

Utility-Scale BESS Project Development & Ownership (IPP/Developer) (EUAFAAAA)

akta.pro secondary industries

BESS Operations, Maintenance & Asset Performance Management (APM) (EUAFAAAG), BESS Financing, Insurance & Contracting (Tax Equity, PPA/Tolling, Warranties) (EUAFAAAI), BESS Market Participation & Trading Services (Ancillary/Capacity/Arbitrage) (EUAFAAAL), Energy Storage & Microgrid Electrical Infrastructure (BESS, Controls) (IMAFAHAE)

Keywords

• Utility-scale battery storage
• Energy storage development
• Grid-scale BESS
• Independent power producer
• Standalone energy storage

Headquarters

HQ city

Boulder

HQ country

United States

HQ region

North America

Offices4 records

Markets served

GTM type

B2B

Offering type

Services

Cost components

Technology or R&D, Operations, Personnel, Infrastructure, Marketing or Sales

Revenue model

1. Energy Storage Capacity Contracts: Flatiron develops and operates utility-scale battery energy storage assets that provide capacity services to grid operators. Revenue is generated through long-term offtake agreements with utilities, capacity auction participation in ISO markets (ISO-NE, NYISO, PJM), and merchant exposure in wholesale electricity markets. Projects earn revenue by displacing expensive peaker plants during high-demand periods, providing grid reliability services, and enabling renewable energy integration.
2. Project Development and Construction Services: The company develops battery storage projects from greenfield through construction, monetizing value through project financing, tax credit transfers, and equity returns upon commercial operation.
3. Landowner Lease Arrangements: Flatiron partners with landowners to host energy storage facilities on their properties through long-term lease agreements (up to 35 years), providing landowners predictable revenue streams while Flatiron manages and optimizes the storage system.

Pricing tiers

Go-to-market motion2 records

Distribution channels4 records

Marketing channels5 records

Core offering

Flatiron Energy develops, builds, owns, and operates standalone utility-scale battery energy storage systems (BESS) ranging from 100 MW to 300 MW with 4-hour duration in the Northeast and Mid-Atlantic US. The company delivers grid reliability, capacity, and ancillary services through long-term offtake agreements with utilities, ISO/RTO capacity auction participation (ISO-NE, NYISO, PJM), and merchant exposure in wholesale electricity markets, with a development pipeline of approximately 4.5 GW/18 GWh and a 16 GWh battery storage pipeline.

Product overview

Flatiron Energy operates as an independent power producer offering a unified platform for utility-scale battery energy storage system (BESS) development, construction, and operations. The company's core offering consists of named BESS projects—including the Taft Project (200 MW/800 MWh), Salt Cod Storage (168 MW/672 MWh), Energizar (250 MW/1,000 MWh), and Lite Brite (300 MW/1.2 GWh)—supported by a corporate credit facility and equity commitments enabling portfolio growth to approximately 4.5 GW/18 GWh. Projects target grid reliability improvement in the Northeast and Mid-Atlantic US, with the company leveraging financing partnerships and battery supply agreements (including SK On for LFP batteries) to deliver projects from development through commercial operation.

Differentiator

Problem solved

Functional benefit

Products and services

• Taft Project A 200 MW / 800 MWh battery energy storage asset located in Uxbridge, Massachusetts, designed to support eastern Massachusetts grid reliability and reach commercial operations in late 2026. It is the largest battery energy storage project in New England.
• Salt Cod Storage A 168 MW / 672 MWh battery energy storage project proposed at the former Montaup coal-fired power plant site along the Taunton River in Somerset, Massachusetts, targeting commercial operation in Q4 2028.
• Energizar A 250 MW / 1,000 MWh battery energy storage project awarded in Massachusetts's first large-scale energy storage tender, serving the Northeast market.
• Lite Brite A 300 MW / 1.2 GWh battery energy storage project located in the Brighton neighborhood of Boston, Massachusetts; currently paused pending safety regulations.
• Utility-Scale BESS Development and Operations Platform Flatiron's core platform encompassing the development, construction, and long-term operation of utility-scale battery energy storage projects across the Northeast and Mid-Atlantic US, with an approximately 4.5 GW / 18 GWh portfolio and 16 GWh pipeline.

Quantifiable outcome

• $3.4 billion in societal benefits to the Northeast by 2030
• +3 more outcomes

Named customers4 records

Segments4 records

Ideal customer profiles3 records

Technology focussed Yes

API detail

Has API

No

API docs

API detail

Core technology

AI maturity

App detail

Feature3 records

Partnerships

One partnership is on record.

• SK OncoreTechnology or Integration · 3 September 2025SK On signed an ESS supply contract with Flatiron Energy for 1 GWh of LFP battery storage initially, with total commitment of up to 7.2 GWh between 2026-2030. SK On is South Korea's battery unit of SK Innovation, supplying batteries to Hyundai, Kia, and Ford. Mass production of ESS-dedicated LFP batteries begins H2 2026, with conversion of Georgia EV production lines for ESS use.

Scale indicators13 records

Recent moves8 records

Expansion highlights6 records

Emerging players

• Stem Inc: AI-driven clean energy storage and software provider with utility-scale and C&I project development. Overlap in asset optimization software and IPP activities in select US markets, though primary focus has historically been C&I rather than utility-scale standalone.
• Form Energy: Developer of long-duration iron-air battery storage systems. Comparable IPP/developer model but with different (100+ hour) duration technology; competes for similar state-level long-duration procurement contracts.

Broad incumbents

• Avantus (formerly 8minute Solar Energy): Large-scale solar and storage developer in the US. Competes for project development, financing relationships, and talent (multiple Flatiron VPs previously held roles at Avantus). Now owned by EDP Renewables.
• Fluence Energy: Global BESS OEM, integrator, and increasingly a project developer/owner. Overlaps in storage technology and asset management software (competing with Flatiron's in-house platform), and competes in IPP/project finance activities in the same US markets.
• RWE Clean Energy: Major European-headquartered utility with significant US renewable and storage development portfolio (previously Invenergy/Innogy). Competes directly for ISO-NE/NYISO/PJM interconnection queue positions and development sites; Flatiron hired its former VP of East Development.
• ENGIE Storage: Global utility with North American storage and renewable development operations. Competes in similar Northeast markets and has been a training ground for multiple Flatiron senior leaders (CEO, COO, CCO all held prior roles at ENGIE or its subsidiaries).

Direct peers

• Plus Power: Independent power producer focused on standalone utility-scale battery energy storage across multiple US ISOs. Most direct comparable business model—develops, owns, and operates standalone BESS projects with similar financing structures and target customers.
• Key Capture Energy: Standalone battery energy storage developer and operator with projects in ISO-NE and other US markets. Closely comparable in scale, IPP business model, and Northeast focus, including participation in Massachusetts storage tenders.
• Aypa Power: Developer and operator of utility-scale battery storage and hybrid projects in North America. Direct competitor in the standalone BESS IPP space with similar project sizes and development pipeline approach.
• NineDot Energy: Urban-focused community battery energy storage developer in the NYISO market. Comparable business model but with a tighter geographic focus on the New York metro area; competes for similar Northeast urban interconnection capacity.

Market position

Strengths5 records

Weaknesses5 records

Competitive moat6 records

Key risks7 records

Key highlights7 records

Customer concentration

Compliance1 record

Revenue estimate

Valuation estimate

Number of profiles

Profiles14 records

Funding overview

Funding rounds3 records

Investors2 records

Funding detail is available on the Subscription and Enterprise plan.Contact sales →

M&A

Investments

M&A and investment is available on the Subscription and Enterprise plan.Contact sales →

Frequently asked questions about Flatiron Energy