Clean Tech Startups You Should Watch in Renewable Energy

3 September 2025

The world is going green, and tech startups are fueling the revolution! Renewable energy isn't just about solar panels on rooftops anymore—innovative companies are diving deep into game-changing solutions that could reshape the way we produce and consume energy.

From turning food waste into electricity to harvesting energy from the ocean, these startups are proof that the future is bright (and sustainable!). So, if you're curious about who's leading the charge, buckle up—because we're about to dive into some incredible clean tech startups you should definitely keep an eye on!

Why Clean Tech Startups Matter

Think about it—our planet is heating up, fossil fuels are running out, and pollution is through the roof. If we don’t make serious changes soon, future generations will be left cleaning up a colossal mess. That’s where clean tech startups come in.

These companies aren’t just here to make money; they’re on a mission to fix the planet. They’re leveraging cutting-edge technology to create cleaner, more efficient ways to power the world. And let’s be real—who wouldn’t want a future where energy is sustainable, affordable, and doesn’t destroy the environment?

Now, let’s talk about the startups that are turning this vision into reality.

1. Heliogen – Supercharging Solar Power

HQ: Pasadena, California
What They Do: Concentrated Solar Power (CSP)

Forget traditional solar panels—Heliogen is taking solar energy to a whole new level. Using artificial intelligence and mirrors, they harness the sun’s heat to produce temperatures exceeding 1,000°C (that’s hotter than lava!).

Why does this matter? Well, such extreme temperatures can replace fossil fuels in industrial processes, like steel and cement production. That means major industries could slash their carbon footprint while still running at full speed.

Why Watch Them?

- Bill Gates is backing them (enough said!).
- They could help cut industrial CO₂ emissions by nearly 20%.
- Their tech makes solar energy even more viable for large-scale operations.

2. Energy Vault – Stacking Blocks for Energy Storage

HQ: Lugano, Switzerland & Westlake Village, California
What They Do: Gravity-Based Energy Storage

If you thought energy storage was all about lithium-ion batteries, think again. Energy Vault is solving renewable energy’s biggest challenge—storage—by using giant bricks.

Here’s how it works: When energy is plentiful (like on a sunny or windy day), their system lifts massive concrete blocks using electric cranes. When energy is needed, they lower the blocks, and that movement generates electricity. Simple, yet brilliant!

Why Watch Them?

- Their system lasts longer than traditional batteries.
- Uses recycled materials for the bricks (eco-friendly, too!).
- A promising alternative to expensive battery storage.

3. Ocean Grazer – Tapping Into the Power of the Sea

HQ: Netherlands
What They Do: Ocean Energy Storage

The ocean is basically Earth’s biggest, most powerful battery, and Ocean Grazer wants to tap into it. Their Ocean Battery stores excess energy generated by offshore wind turbines in the seabed.

It works by pumping water into underground reservoirs when there’s extra energy. When demand spikes, the water is released, turning turbines that generate electricity. This could make renewable energy production much more reliable.

Why Watch Them?

- A game-changer for offshore wind farms.
- No toxic chemicals like traditional batteries.
- Uses nature’s most powerful force—water!

4. Ampaire – Making Aviation Greener

HQ: Los Angeles, California
What They Do: Hybrid-Electric Aircraft

Ever wondered if airplanes could go electric? Well, Ampaire is making it happen. They’re creating hybrid-electric aircraft that drastically reduce fuel consumption and emissions.

Their planes use a mix of battery and fuel-powered propulsion, similar to how hybrid cars work. The result? A more sustainable aviation industry without sacrificing performance.

Why Watch Them?

- Air travel is a massive carbon emitter—this could change that.
- Makes electric flight a reality without redesigning entire aircraft fleets.
- They’ve already completed successful test flights.

5. Twelve – Turning CO₂ into Useful Products

HQ: Berkeley, California
What They Do: Carbon Transformation

Twelve is giving CO₂ a second chance—literally. Instead of letting carbon dioxide pollute the air, they transform it into everyday products like fuel, plastics, and even sunglasses.

Their tech, called "carbon transformation," uses electricity and water to turn CO₂ into something useful, reducing emissions while creating sustainable materials.

Why Watch Them?

- Directly fights climate change by reducing CO₂.
- Could replace fossil fuels in making everyday products.
- Big brands like Mercedes-Benz and Procter & Gamble are already interested.

6. Solar Water Solutions – Clean Drinking Water Using the Sun

HQ: Finland
What They Do: Solar-Powered Desalination

Nearly 2 billion people lack access to clean drinking water, but Solar Water Solutions has a fix. They’ve built solar-powered devices that can desalinate seawater without needing a power grid.

This means remote communities can have an unlimited water supply, just by using the sun. Plus, it’s completely emissions-free!

Why Watch Them?

- Provides clean water to off-grid communities.
- 100% renewable energy-powered.
- Could revolutionize water access in developing regions.

7. Redwood Materials – Recycling Batteries the Smart Way

HQ: Carson City, Nevada
What They Do: Advanced Battery Recycling

With electric cars taking over, battery waste is becoming a real problem. Redwood Materials is tackling that issue by recycling old lithium-ion batteries and recovering valuable materials like lithium, nickel, and cobalt.

Instead of mining new materials (which is terrible for the planet), they reuse the ones we already have, making the EV industry much more sustainable.

Why Watch Them?

- Critical for the future of electric vehicles.
- Reduces dependency on harmful mining operations.
- Founded by JB Straubel (Tesla’s former CTO—so he knows his stuff!).

The Future of Renewable Energy is Bright!

These innovative startups prove that clean tech isn’t just a buzzword—it’s the future. From the ocean’s depths to the skies above, companies worldwide are pushing the boundaries of what’s possible to create a more sustainable and energy-efficient world.

So, whether you're an investor looking for the next big thing or just someone who wants a cleaner planet, keep your eyes on these startups. They might just change the world!