Breakthrough Energy startups are attacking the energy transition from almost every imaginable direction: better batteries, underground transmission lines, new solar cells, hydrogen hidden beneath the Earth, cleaner fuels and even materials that could make electrical wires perform better.
The companies form the fifth cohort of Breakthrough Energy Fellows, an early-stage program created by Breakthrough Energy, the climate and energy organization founded by Bill Gates.
The 2025 cohort brought together 45 innovators working across 22 companies. Roughly half of the teams were based outside the United States, making it the program’s most international group at the time. Breakthrough Energy said the cohort included teams from the U.S., Asia, Canada, Germany, the U.K. and South Africa.
These are not simply another group of software startups chasing quick growth.
Many are attempting to commercialize technologies involving advanced chemistry, materials science, energy infrastructure and biology — fields where moving from an interesting laboratory result to an economically viable product can take years.
That is exactly the gap Breakthrough Energy wants its Fellows program to address.
Why Breakthrough Energy Startups Are Different
Breakthrough Energy Fellows targets technologies that are still very early in their development.
The organization says its Innovator Fellowship generally looks for technologies around technology-readiness levels 1 to 4, often before they have attracted significant traditional venture funding. Projects are expected to have a potential pathway to reducing or capturing greenhouse-gas emissions at enormous scale.
The program provides research funding, technical support, mentorship and access to Breakthrough Energy’s wider network. Current program guidelines say Innovator projects can typically receive up to $500,000 in catalytic investment.
That early intervention matters because climate hardware faces a problem software companies rarely encounter.
A promising battery material, industrial reactor or transmission technology cannot simply be uploaded to the cloud and distributed globally. It has to be engineered, tested, manufactured, certified and eventually produced at competitive prices.
Breakthrough Energy is effectively looking for promising technologies before many conventional investors would be comfortable backing them.
For the fifth cohort, the organization reviewed about 1,500 applications and referrals before selecting the final teams.
Here are the Breakthrough Energy startups that made the cut.
1. Path Power Wants to Rethink Power Transmission
Path Power is developing a self-boring high-voltage cable system designed to make underground power transmission faster and less disruptive.
Transmission has become a major bottleneck for electricity systems. New renewable generation and growing electricity demand mean countries need significantly more grid infrastructure, but traditional power-line projects can take years to permit and build.
Path Power believes underground installation could provide another option, particularly where overhead transmission is difficult.
Breakthrough Energy describes the company as developing a self-boring system aimed at reducing the cost and disruption associated with installing high-voltage underground lines.
2. PowerNaP Energy Is Betting on Sodium-Ion Batteries
PowerNaP Energy is working on materials that could make sodium-ion batteries more competitive with lithium-ion technology.
The company is developing battery materials intended to increase sodium-ion energy density while taking advantage of sodium’s abundance.
Its goal is ambitious: approach lithium-ion performance at significantly lower cost.
If sodium-ion batteries continue improving, they could eventually become particularly attractive for stationary storage and applications where cost and raw-material availability matter more than maximum energy density.
3. LiftOFF Technology Is Pushing Battery Energy Density Higher
LiftOFF Technology is taking another approach to batteries.
Rather than focusing on sodium, the company is developing a battery chemistry intended to dramatically increase energy density while using more readily available elements.
Breakthrough Energy says the technology could ultimately support difficult-to-electrify applications including aviation, maritime transport and edge computing.
For sectors such as aviation, every kilogram matters, making energy density one of the biggest barriers to replacing fossil fuels with batteries.
4. Beyond Silicon Wants More Efficient Solar Cells
Beyond Silicon is developing perovskite-on-silicon tandem solar cells.
Instead of relying on one light-absorbing material, tandem cells combine different materials that capture different portions of the solar spectrum.
The company is targeting solar conversion efficiencies above 30%, potentially allowing panels to generate substantially more electricity from the same surface area.
Breakthrough Energy describes Beyond Silicon as building tandem cells capable of moving solar beyond the efficiency limits of conventional silicon technology.
5. Teragon Energy Is Working on Power Electronics
Teragon Energy is developing power-electronics technology.
Power electronics might not receive the attention of solar panels or batteries, but the technology controls how electricity is converted and moved through everything from renewable-energy systems to electric vehicles and industrial machines.
Better converters could reduce electricity losses and make increasingly electrified infrastructure more efficient.
Teragon was among the companies named in Breakthrough Energy’s fifth Fellows cohort.
6. Entropy Lab Wants Buildings to Cool Themselves
Entropy Lab is developing paints and coatings that passively cool buildings.
Its materials are designed to manage heat through radiative and evaporative cooling, reducing how much electricity buildings need for air conditioning.
That could be increasingly important as cooling demand rises in hot and rapidly urbanizing regions.
Breakthrough Energy describes Entropy Lab as optimizing material properties to create coatings that reduce building temperatures while helping address the urban heat-island effect.
7. C STAR Is Turning CO₂ Into Fuel
C STAR is trying to treat carbon dioxide as a raw material rather than simply waste.
The company is developing technology that combines captured CO₂ with renewable hydrogen to produce hydrocarbon fuels.
The idea is to create fuels compatible with existing infrastructure without continually introducing additional fossil carbon into the system.
Breakthrough Energy says C STAR is targeting decentralized fuel production as an alternative to conventional fossil-based manufacturing.
8. Spark e-Fuels Is Also Chasing Synthetic Fuels
Spark e-Fuels is developing synthetic fuels designed around intermittent renewable electricity.
The startup’s system aims to adjust production depending on when low-cost renewable electricity is available.
That could help address one of synthetic fuel’s biggest problems: the enormous amount of clean electricity needed to make it economically and environmentally worthwhile.
Its initial targets include aviation and other industries where replacing liquid fuels remains difficult.
9. Green COP Turns Agricultural Waste Into Fuel
Singapore-based Green COP takes a biological route.
The company is developing a process for producing second-generation biobutanol from agricultural waste.
Rather than using food crops as its main feedstock, Green COP wants to extract value from residues that might otherwise be burned, discarded or left unused.
The company is one of several Southeast Asian startups brought into Breakthrough Energy’s Fellows network through its regional partnership with Enterprise Singapore and Temasek.
10. Valoron Wants Fuel From Difficult Waste
Valoron is targeting another enormous source of carbon: waste that cannot easily be recycled.
Its technology is designed to convert non-recyclable waste into chemicals and fuels that can be used by industries where emissions remain difficult to eliminate.
The approach could potentially tackle two problems at once by diverting waste from disposal while reducing dependence on newly extracted fossil feedstocks.
11. GeoKiln Is Searching for Hydrogen Underground
GeoKiln is developing technology to produce hydrogen directly from iron-rich rocks beneath the Earth’s surface.
This emerging field is generally described as stimulated geologic hydrogen.
Instead of manufacturing hydrogen using electricity or natural gas, companies hope to trigger or accelerate chemical reactions underground that naturally generate hydrogen.
GeoKiln says it plans to borrow proven techniques from the oil and gas industry to access the resource.
12. Anning Corporation Is Making a Similar Hydrogen Bet
Anning Corporation is also pursuing stimulated geologic hydrogen.
The company aims to harness reactions between water and iron-rich rock formations to generate hydrogen underground.
Interest in geologic hydrogen has grown because, if the resource can be produced reliably and cheaply, it could offer another source of low-carbon fuel without requiring the enormous amounts of electricity consumed by conventional green-hydrogen electrolysis.
Breakthrough Energy describes Anning’s mission as producing clean hydrogen directly from natural subsurface processes.
13. Thunderstone Wants Critical Minerals Without Traditional Mining
Thunderstone is trying to change how minerals are extracted.
Its technology uses high-voltage electricity to loosen underground mineral deposits.
The long-term goal is to make resources accessible without relying on some of the large excavations and tailings facilities associated with conventional mining.
Demand for copper and other critical minerals is expected to grow alongside electrification, making cleaner extraction technologies increasingly important.
14. Voluna Uses Neutrons to Map Minerals
Voluna is taking a different approach to critical minerals.
The company is developing autonomous neutron technology for real-time geochemical mapping.
Better underground information could help miners locate resources more accurately and reduce unnecessary drilling.
Breakthrough Energy lists Voluna’s technology among its critical-minerals projects.
15. Arcturus Is Reinventing Electrical Conductors
Arcturus emerged from stealth in 2026 with technology that infuses metals with advanced carbon nanomaterials.
The company wants to create conductors with better combinations of electrical conductivity, strength, weight and thermal performance.
Arcturus says its technology could eventually improve electric motors, data centres, thermal systems and the wider electricity grid.
In June 2026, it announced an $8 million seed round, bringing its total capital raised to $10 million.
16. Hyperion Transport Systems Is Building Better Space Propulsion
Not every Breakthrough Energy startup is focused on infrastructure on Earth.
Hyperion Transport Systems is developing an electric thruster for spacecraft.
Its technology is designed to increase both fuel efficiency and thrust density, potentially reducing how much propellant satellites need while improving their ability to manoeuvre.
That could become increasingly valuable as the number of satellites and other spacecraft in orbit grows.
17. DeepCycle Eco Wants Truly Circular PET Plastic
Singapore’s DeepCycle Eco is developing technology to break PET waste back into its original molecular building blocks.
That is different from simply melting and reshaping plastic.
Returning PET to its original monomers could allow manufacturers to create new material with characteristics closer to virgin plastic, opening the door to a more genuinely circular system.
Breakthrough Energy says the goal is a closed-loop process that reduces both plastic pollution and emissions.
18. Everbloom Is Turning Waste Protein Into Textiles
Everbloom is tackling fashion’s materials problem.
The company transforms discarded proteins into fibres designed to mimic premium textiles such as wool and cashmere.
Instead of depending entirely on animals, petroleum-derived fibres or newly produced agricultural materials, Everbloom wants to turn existing waste streams into useful clothing fibres.
It is an unusual example of how Breakthrough Energy’s definition of climate technology extends well beyond power generation.
19. Terra Oleo Is Growing Oils With Microbes
Terra Oleo is using microbial fermentation to produce fats and oils.
Those ingredients are everywhere, from food and cosmetics to industrial products.
Producing them through engineered microorganisms could eventually provide alternatives to agricultural or fossil-derived inputs.
The Singapore-based company joined Breakthrough Energy Fellows through its Southeast Asia program.
20. Advanced Agriscience Wants Crops to Survive Frost
Advanced Agriscience is using biology to protect plants from frost damage.
The company is developing autonomously operating microbes intended to improve agricultural resilience when temperatures suddenly fall.
Climate technology increasingly involves adaptation as well as reducing emissions, and protecting food production from extreme weather is becoming an important part of that conversation.
Breakthrough Energy lists the technology under adaptation and resilience.
21. Qarbotech Wants Plants to Use Light More Efficiently
Malaysia’s Qarbotech is applying carbon nanomaterials to agriculture.
Its technology is designed to improve how efficiently plants use light, potentially increasing crop yields without requiring a corresponding rise in land, fertilizer or other inputs.
Breakthrough Energy describes the company’s approach as combining higher agricultural productivity with lower-emission farming.
22. Vertility Health Is Rethinking Cattle Breeding
Vertility Health is developing technology that helps farmers select sperm for specific livestock traits without genetically editing the animals.
Those traits could include characteristics linked to productivity and feed efficiency.
More efficient cattle production could reduce the environmental footprint associated with producing the same amount of meat or dairy.
The technology demonstrates how far the definition of Breakthrough Energy startups now extends beyond traditional energy companies.
Breakthrough Energy Startups Have to Prove the Economics
Perhaps the most interesting change in the Fellows program is that Breakthrough Energy is putting more emphasis on economics earlier in the development process.
The organization has been encouraging founders to use techno-economic analysis to determine whether a technology can realistically compete in the market before years are spent developing it.
Ashley Grosh, then a vice president at Breakthrough Energy, told TechCrunch that previous Fellows sometimes entered the program expecting to build one product before discovering that another application made more economic sense. The program increasingly tries to identify those pivots earlier.
That is an important distinction.
A technology can work perfectly and still fail as a business.
Green hydrogen, synthetic fuel, advanced batteries and next-generation materials ultimately have to compete with enormous industries whose infrastructure has been built and optimized over decades.
Being cleaner is unlikely to be enough on its own. The technology also needs to become reliable, manufacturable and affordable.
From Experimental Science to Real Companies
Breakthrough Energy’s broader strategy is based on the idea that some of the technologies needed for the next generation of energy systems have not yet reached commercial maturity.
The Fellows program focuses on that earliest stage.
Breakthrough Energy says it provides R&D financing, mentorship, commercialization support and access to its wider network so founders can move technologies from the laboratory toward the market.
Previous cohorts suggest at least some of those early bets are progressing. Breakthrough Energy staff have said that roughly 98% of teams from earlier cohorts secured follow-on funding, with many moving toward pilot projects and customer deployments.
The fifth cohort also shows how much the definition of energy innovation has expanded.
It includes solar cells and batteries, but also livestock genetics, agricultural microbes, synthetic textiles, satellite propulsion, recycling, mining technologies and advanced electrical conductors.
The common thread is not one particular technology.
It is the attempt to solve problems that become increasingly important in a world using more electricity, more materials and more infrastructure.
Bill Gates has repeatedly argued that rising global energy demand means the world will need clean technologies that can compete on both reliability and cost. Breakthrough Energy says global electricity demand could roughly double from about 27,000 TWh in 2024 to around 51,000 TWh by 2050.
The 22 Breakthrough Energy startups are still very early in that journey. Some technologies may work. Others may change direction, and some may never reach commercial scale.
That uncertainty is part of the point.
Breakthrough Energy is placing its support at the stage where the science is promising, the commercial outcome is far from guaranteed, and traditional investors might still consider the technology too early.
If even a handful of these ideas eventually become major industries, today’s experimental batteries, underground hydrogen systems, carbon-infused wires and waste-derived fuels could look considerably less experimental a decade from now.
