7881 indexable Environment companies headquartered in United States, ranked by total equity funding and recent funding momentum. Combined disclosed equity funding of $93.6B across 1221 funded companies, including 4 unicorns.
| # | Company | Funding | Valuation | Stage | Latest round | Employees | Founded | Momentum |
|---|---|---|---|---|---|---|---|---|
| 1 |
Madison Air
Homepage | Madison Air |
$10.9B | — | Public | Series D Apr 2026 | — | 2005 | ↑ Active |
| 2 |
Silicon Ranch
developer of solar power projects |
$1.9B | — | Series G | Series G May 2026 | 115 | 2010 | ↑ Active |
| 3 |
SolarLandscape
Provider of solar integration & project financing services |
$600M | — | Funding Raised | Conventional Debt May 2026 | 91 | 1985 | ↑ Active |
| 4 |
Valar Atomics
Manufacturer of nuclear fission reactors |
$599M | — | Series B | Series B Apr 2026 | — | 2023 | ↑ Active |
| 5 |
SHINE Technologies
Producer of nuclear isotopes using fusion techniques |
$413.6M | — | Series D | Series D Feb 2026 | 165 | 2005 | ↑ Active |
| 6 |
Enfinity
Developer of solar energy projects |
$388.4M | — | Series D | Conventional Debt Feb 2026 | 265 | 2005 | ↑ Active |
| 7 |
CFS
Provider of tokamak nuclear fusion reactors |
$2.1B | — | Series B | Series B Aug 2025 | 151 | 2018 | ↑ Active |
| 8 |
Inertia
Developer of technology pursuing commercialization of fusion energy production |
$450M | — | Series A | Series A Feb 2026 | — | 2024 | ↑ Active |
| 9 |
Dominion Energy
Producer and transporter of energy |
$4B | — | Acquired | Grant (prize money) May 2025 | 17,700 | 1983 | ↑ Active |
| 10 |
X Energy
Developer of small modular & high temperature gas cooled nuclear reactor |
$605M | — | Public | Series D Nov 2025 | 246 | 2010 | ↑ Active |
| 11 |
ArtIn Energy
Help sustain a carbon-free world by producing hydrogen using solar energy and water for clean, efficient electricity and heat generation |
$255M | — | Series A | Series A Mar 2026 | — | 2012 | ↑ Active |
| 12 |
Ascent Solar
Manufacturer of flexible thin-film solar panels for varied applications |
$265.2M | — | Public | Post IPO Jan 2026 | 16 | 2005 | ↑ Active |
| 13 |
CrossBoundary Energy
Provider of fully financed renewable energy solutions for commercial and industrial clients |
$83M | — | Series B | PE Apr 2026 | 21 | 2014 | ↑ Active |
| 14 |
Torus
Manufacturer of power generators and energy management app |
$67M | — | Series D | Conventional Debt May 2026 | 1 | 2021 | ↑ Active |
| 15 |
Terrestrial Energy
Developer of small modular reactor |
$76.2M | — | Series D | Series D Mar 2026 | 78 | 2013 | ↑ Active |
| 16 |
DSD
Provider of solar panel installation and operation & maintenance services |
$605M | — | Acquired | Conventional Debt Aug 2025 | 192 | 2012 | ↑ Active |
| 17 |
Sylmar Group
Provider of industrial water treatment services |
$130M | — | Funding Raised | Conventional Debt Feb 2026 | 6 | 2019 | ↑ Active |
| 18 |
TAE Technologies
Unicorn Developer of FRC nuclear fusion reactors |
$1.2B | $2.6B as of 2019 |
Series G | Series G Jun 2025 | 224 | 1998 | ↑ Active |
| 19 |
Terra Energy
Provider of solar energy solutions for residential properties, offering a subscription model with no upfront costs and no long-term contracts |
$140.2M | — | Series D | Series D Jan 2026 | — | 2016 | ↑ Active |
| 20 |
Madison Energy Investments
Provider of platform for investors |
$800M | — | Acquired | Conventional Debt Sep 2025 | 32 | 2019 | ↑ Active |
| 21 |
TerraPower
Designer of nuclear reactors |
$810M | — | Series D | Series D Jun 2025 | 299 | 2006 | ↑ Active |
| 22 |
Aspen Power
Provider of renewable energy asset development, construction, and operation services |
$120M | — | Acquired | Conventional Debt Jan 2026 | 66 | 2020 | ↑ Active |
| 23 |
NextEra Energy
Developer of energy solutions |
$2.8B | — | Acquired | Post IPO Feb 2025 | 9,500 | 1925 | ↑ Active |
| 24 |
Array Technologies
Manufacturer of solar trackers |
$845.9M | — | Public | Post IPO Jun 2025 | 14 | 1992 | ↑ Active |
| 25 |
Nautilus Solar
Community solar provider offering savings and supporting clean energy initiatives |
$339M | — | Acquired | Conventional Debt Sep 2025 | 57 | 2006 | ↑ Active |
| 26 | Claros | $39.8M | — | Seed | Seed Mar 2026 | — | 2024 | ↑ Active |
| 27 |
Soltage
Clean energy solutions provider: development, finance, and operation of renewable projects |
$82.1M | — | Acquired | Conventional Debt Dec 2025 | 23 | 2005 | ↑ Active |
| 28 |
Recurrent Energy
Developer of utility-scale solar projects |
$585M | — | Acquired | Conventional Debt Apr 2025 | 110 | 2006 | ↑ Active |
| 29 |
Radiant Nuclear
Unicorn Developer of portable nuclear microreactors designed to replace diesel generators |
$55M | — | Series D | Series D Dec 2025 | 34 | 2019 | ↑ Active |
| 30 |
Last Energy
Developer of small modular reactor |
$64M | — | Series C | Series C Dec 2025 | 45 | 2019 | ↑ Active |
| 31 |
Treaty Oak Clean Energy
Developer of utility scale solar projects |
$300M | — | Acquired | Conventional Debt Aug 2025 | 20 | 2021 | ↑ Active |
| 32 |
Avalanche
Developer of energy-dense fusion microreactors for clean power generation |
$45M | — | Series A | Series A Dec 2025 | — | 2018 | ↑ Active |
| 33 |
LIS Technologies
Provider of laser isotope separation technologies optimized for uranium (HALEU) power generation |
$13.5M | — | Series A | Series A Mar 2026 | — | 2023 | ↑ Active |
| 34 |
PureCycle
Provider of waste plastic recycling services |
$722.3M | — | Public | Post IPO Feb 2025 | 177 | 2015 | ↑ Active |
| 35 |
Helion
Unicorn Provider of deuterium fuel-based magnetic-nuclear fusion reactor |
$552.1M | $1.2B as of 2020 |
Series F | Series F Jan 2025 | 44 | 2010 | ↑ Active |
| 36 |
Antares Industries
Provider of micro-sized nuclear reactors for remote off-grid |
$38.1M | — | Series B | Series B Dec 2025 | — | 2023 | ↑ Active |
| 37 |
Husk Power Systems
AI-powered distributed energy platform delivering clean, reliable power in Global South |
$74.3M | — | Series D | Conventional Debt Sep 2025 | 443 | 2007 | ↑ Active |
| 38 |
Pine Gate Renewables
Developer of utility-scale solar and energy storage projects |
$1.1B | — | Series E | Series E Oct 2024 | 1,099 | 2016 | ↑ Active |
| 39 |
Invenergy
Developer and operator of sustainable energy solutions |
$575M | — | Acquired | Series D Jan 2025 | 1,276 | 2000 | ↑ Active |
| 40 |
Scenic Hill Solar
Developer of solar energy projects |
$31.8M | — | Funding Raised | Conventional Debt Dec 2025 | 12 | 2015 | ↑ Active |
| 41 |
Orano
Fuel and power producer in the nuclear energy sector |
$307.9M | — | Public | Grant (prize money) Mar 2025 | 19,683 | 2001 | ↑ Active |
| 42 |
Pattern Energy Group
Renewable Energy focused IPP |
$256.1M | — | Acquired | Post IPO Jun 2025 | 491 | 2013 | ↑ Active |
| 43 |
BKV
Producer of net-zero natural gas, pursuing carbon-neutral energy solutions. This company focuses on making natural gas production carbon-neutral, addressing the need for a rapid transition to net-zero energy. They are actively involved in carbon capture projects and are committed to sustainable energy practices. The company's operations emphasize operational excellence, employing advanced technologies and prioritizing carbon-negative initiatives. They also prioritize community engagement and responsible stakeholder relationships. |
$250M | — | Public | Post IPO May 2025 | 158 | 2015 | ↑ Active |
| 44 |
City of Rapid City
Provider of water management services |
$74.7M | — | Funding Raised | Grant (prize money) Aug 2025 | 302 | 2001 | ↑ Active |
| 45 |
Standard Thermal
Developer of thermal energy storage for solar power applications |
$10.8M | — | Series B | Series B Mar 2026 | — | 2021 | ↑ Active |
| 46 |
SUNation
Offers commercial and residential solar solutions |
$6.7M | — | Acquired | Seed Apr 2026 | 106 | 2003 | ↑ Active |
| 47 |
Onyx Renewable Partners
Renewable Energy development company |
$132M | — | Late Stage | Conventional Debt Jun 2025 | 69 | 2014 | ↑ Active |
| 48 |
NuCube Energy
Nuclear fission technology, developing innovative micro-reactor solutions to transform the way our society is powered |
$13M | — | Series B | Series B Feb 2026 | — | 2023 | ↑ Active |
| 49 |
Applied Atomics
Operator of on-site nuclear fission plants providing dedicated power to industries |
$8.3M | — | Seed | Seed Mar 2026 | — | 2025 | ↑ Active |
| 50 |
Realta Fusion
Developer of nuclear energy projects |
$9M | — | Series A | Conventional Debt Feb 2026 | 5 | 2021 | ↑ Active |
As one of the world’s largest privately held companies, Madison Air exists to help our customers realize the often invisible, but very real return better air has for us all.
developer of solar power projects
Provider of solar integration & project financing services
Manufacturer of nuclear fission reactors
Producer of nuclear isotopes using fusion techniques
Developer of solar energy projects
Provider of tokamak nuclear fusion reactors. It uses rare-earth barium copper oxide in high-field superconducting magnets for the working of compact fusion reactors.
Developer of technology pursuing commercialization of fusion energy production. The company focuses on a direct path to commercial energy using a diode-pumped, solid state laser driving an indirect drive target with Deuterium-Tritium fuel. It aims to retire risk areas in laser design, target fabrication, and power plant design. The company plans to construct a demonstrator fusion power plant.
In 2022, the company recorded annual revenues of $17.17B and a net profit of $0.99B.
Developer of small modular & high temperature gas cooled nuclear reactor. It operates through tri-structural isotropic particle fuel. And also offers pebble bed nuclear reactor, zero emission energy, neutronics, and nuclear engineering services.
Artinenergy is dedicated to revolutionizing the energy sector by using solar energy to produce hydrogen for clean, efficient electricity and heat generation without CO2 emissions. They are leading the clean energy transition to help sustain a carbon-free world.
Manufacturer of flexible thin-film solar panels for varied applications. These photovoltaic modules are suitable for airborne vehicles, space missions, and agrivoltaic installations. The company utilizes CIGS chemistries with roll-to-roll manufacturing processes. The panels are built on a thin polyamide substrate.
Rankings are computed by Radar (Fliar BI) from the Radar company master and are updated periodically. Funding and momentum scores use disclosed equity-funding data only. Figures may lag private rounds. Last updated 2026-06-16.
