Discover 10 cleantech startups transforming energy, transportation, and resource management with sustainable solutions. These innovations improve efficiency, reduce emissions, and support a cleaner future.
This article highlights technologies like sustainable hydrogen production, CO2-to-fuel conversion, and retrofitting diesel engines for lower emissions.
Learn how these clean technology companies are advancing renewable energy financing, waste-to-soil solutions, and sustainable mineral extraction to drive global sustainability efforts.
Global Startup Heat Map highlights 10 Cleantech Startups to Watch
Through the Big Data & Artificial Intelligence (AI)-powered StartUs Insights Discovery Platform, covering over 5M+ startups, 20K+ technology trends plus 150M+ patents, news articles & market reports, we identified 1950+ clean tech companies.
The Global Startup Heat Map below highlights the 10 cleantech startups you should watch in 2025 as well as the geo-distribution of 1950+ startups & scaleups we analyzed for this research.
According to our data, we observe high startup activity in Western Europe and the United States, followed by India. The top 5 Startup Hubs for cleantech are London, New York, Singapore, San Francisco, and Paris.
Discover Emerging Cleantech Startups to Watch in 2025
We hand-picked startups to showcase in this report by filtering for their technology, founding year, location, funding, and other metrics.
These clean technology startups work on solutions ranging from retrofit systems and mineral extraction to metal recycling and energy project financing.
- Surrey H2 – Sustainable Hydrogen Production
- Saarthi GreenTech – Retrofit System for Diesel Vehicles
- Rivtide Power – Turbines for Slow Flowing Water
- PureLi – Sustainable Mineral Extraction
- Ethox Energy – Clean Fuels from Waste CO2
- ON2Quest – Sustainable Gas Generation & Purification
- BrewNature – Waste to Soil Solution
- RarEarth – Precious Metal Recycling
- Clean Calcs – Renewable Energy Calculations
- CapeZero – Renewable Energy Project Financing
1. Surrey H2
- Founding Year: 2023
- Location: Surrey, UK
- Use For: Sustainable Hydrogen Production
Surrey H2 develops patented hybrid water-splitting technology for efficient and sustainable hydrogen production using renewable energy sources.
It integrates thermochemical metal/metal oxide water splitting with electrochemical steps, reducing energy consumption and operating at lower temperatures.
The system regenerates metal/metal oxide loops with optimized metallurgical techniques to produce high-pressure green hydrogen.
Water serves as the sole feedstock, while the technology ensures compatibility with oil and gas infrastructure for scalability.
2. Saarthi GreenTech
- Founding Year: 2023
- Location: Sydney, Australia
- Use For: Retrofit System for Diesel Vehicles
Saarthi GreenTech develops GreenDrive, a retrofit system for diesel vehicles that improves fuel combustion and reduces harmful emissions.
It generates low-pressure hydrogen-oxygen (HHO) gas from distilled water using electrolysis, operating at a safe pressure of 0.05 bar.
The system integrates with the vehicle’s 24V battery, consuming minimal power and requiring no external energy sources for operation.
HHO gas mixes with diesel in the engine’s combustion chamber to improve thermal efficiency and reduce unburned fuel residues.
Field tests demonstrate significant fuel savings along with significant reductions in CO2, NOx, and particulate emissions.
3. Rivtide Power
- Founding Year: 2023
- Location: Banchory, UK
- Use For: Turbines for Slow Flowing Water
Rivtide Power develops the Mass of Water Turbine (MOWT), a hydrokinetic system that generates electricity from slow-flowing water.
MOWT uses a conveyor mechanism with paddles that obstruct water flow, driving the conveyor and powering an onboard generator.
The system captures energy at flow speeds even below 2 meters per second – suitable for rivers, tidal estuaries, and ocean currents.
Adjustable buoyancy modules allow self-deployment to enable the turbine to operate either floating at the surface or fully submerged underwater.
Its scalable design supports low-kilowatt outputs for individual use or multi-megawatt systems for grid-scale energy production.
4. PureLi
- Founding Year: 2023
- Location: Newark, New Jersey, USA
- Use For: Sustainable Mineral Extraction
PureLi develops advanced evaporation technologies for sustainable mineral extraction, focusing on lithium, potassium, and nitrate from brine sources.
Its Lilypad system enhances evaporation by concentrating photons, increasing heat retention in water, and accelerating evaporation rates for mineral recovery.
The system improves overall efficiency in brine pond operations, reducing the time and resources required for traditional extraction methods.
E-LITE technology offers a modular solution for lithium extraction from low-concentration brines without relying on large evaporation ponds.
It minimizes energy and chemical use while recovering clean water, ensuring an environmentally friendly and efficient extraction process.
5. Ethox Energy
- Founding Year: 2023
- Location: Calgary, Canada
- Use For: Clean Fuels from Waste CO2
Ethox Energy develops a proprietary process that uses captured CO2 to produce dimethyl ether (DME) blends for clean fuel applications.
It converts sequestered CO2 into low-carbon DME through catalytic synthesis and blends it with propane or diesel alternatives.
The fuel matches energy density while reducing greenhouse gas emissions in turbines, engines, and generators.
The startup designs its technology to integrate with existing infrastructure, enabling minimal retrofitting and modular scalability for various industrial applications.
Want to Explore 1950+ Cleantech Startups & Scaleups?
6. ON2Quest
- Founding Year: 2023
- Location: Singapore
- Use For: Sustainable Gas Generation & Purification
ON2Quest offers advanced gas generation and purification technologies to support industrial applications, focusing on sustainability.
Its nitrogen generators use pressure swing adsorption (PSA) and membrane technology to generate high-purity nitrogen.
The startup also produces oxygen generators that achieve up to 90–95% purity using PSA technology for medical, industrial, and wastewater treatment applications.
It integrates PSA systems and catalytic reactions into hydrogen purification systems to deliver pure hydrogen and remove oxygen effectively.
Moreover, ON2Quest creates gas recycling systems to purify spent industrial gases, recover valuable resources, and reduce reliance on fresh gas production.
7. BrewNature
- Founding Year: 2023
- Location: Saskatoon, Canada
- Use For: Waste to Soil Solution
BrewNature provides advanced in-vessel composting systems that efficiently transform organic waste into nutrient-rich compost.
Its microbial technology optimizes temperature, oxygen, and moisture levels to accelerate decomposition, reducing composting time to a few days.
The automated system uses sensors and real-time monitoring to precisely control the composting process and maintain consistent output quality.
Its insulated design ensures year-round operation in extreme weather while keeping energy consumption low, similar to a household dishwasher.
8. RarEarth
- Founding Year: 2023
- Location: Milan, Italy
- Use For: Precious Metal Recycling
RarEarth develops advanced recycling technology to recover rare earth elements, including neodymium and dysprosium, from end-of-life electric motors.
It disassembles motors and extracts Neodymium Iron Boron (NdFeB) magnet alloy, copper, aluminum, and iron fractions with precision. The startup uses a proprietary chemical process that separates rare earth elements with a non-hazardous, reusable solution.
It reprocesses recovered NdFeB alloy to produce high-quality magnets that match the performance of magnets made from virgin materials.
RarEarth thus eliminates hazardous waste and reduces resource intensity, providing a sustainable solution to meet rare earth demand and reduce mining reliance.
9. Clean Calcs
- Founding Year: 2023
- Location: Austin, Texas, USA
- Use For: Renewable Energy Calculations
Clean Calcs provides computational tools for renewable energy systems, including electric vehicle (EV) charging stations, solar installations, and energy storage solutions.
Its EV Charging Station Calculator generates NEC-compliant load calculations and panel schedules for Level 2 and Level 3 DC chargers. The Commercial Solar Calculator simulates operations, offering DC string sizing, wire sizing, voltage drop analysis, and grounding transformer sizing features.
It ensures compliance with NEC Code versions from 2014 to 2023, streamlining solar system designs for commercial and utility-scale projects. The Energy Storage Calculator simulates loads to determine capacity requirements, supporting partial or whole home backup for a few hours.
10. CapeZero
- Founding Year: 2023
- Location: New York City, New York, USA
- Use For: Renewable Energy Project Financing
- Funding: Raised USD 2.6 million in January 2025
CapeZero develops a platform that simplifies project and infrastructure financing for clean energy developers, optimizing financial modeling and decision-making.
The platform enables users to build financing models, incorporating tax equity, cash equity, transferability, hybrid, direct pay, and debt structures.
It uses advanced algorithms to perform real-time scenario analysis, integrating tax credits, depreciation schedules, cash flow, and debt repayment structures.
The system automates complex financial analytics, reducing modeling time from months to minutes, thus increasing project finance teams’ efficiency.
Discover All Emerging Cleantech Startups
This overview highlights just a few cleantech solutions from 1950+ new companies currently covered by the Discovery Platform. To explore them all, book a personalized demo or download our free Cleantech Innovation Report for a quick overview.
