7 Emerging Energy Technologies Attracting Start-Up Investment

These are the seven emerging energy technologies attracting the most start-up investment, ranked by how much equity funding their start-ups raised in 2025. The figures come from the International Energy Agency's State of Energy Innovation 2026 report.

Nuclear fission leads with about USD 2.6 billion, just ahead of fusion energy. Together, the seven areas raised about USD 9.7 billion, more than a third of all energy start-up funding in 2025, at a time when total funding fell to its lowest level since 2020.

Emerging Energy Technologies Ranked by Start-Up Funding

1. Nuclear Fission

Nuclear fission start-ups raised about USD 2.6 billion in 2025, the most of any emerging area and around 2.7 times their 2024 total. Most of this money is going to small modular reactors, which are designed to be built in factories and installed more quickly than large plants.

The two biggest deals were both in the United States. X-energy raised USD 700 million for a high-temperature, gas-cooled reactor, and TerraPower raised USD 633 million for a sodium-cooled design.

The report notes that only US start-ups raised more than USD 100 million in this area. Nuclear fission and fusion were the main focus of venture funding for US energy start-ups in 2025.

2. Fusion Energy

Fusion start-ups raised about USD 2.2 billion in 2025, down from almost USD 3 billion in 2024. Even so, fusion has raised more than any other emerging area over the past five years.

Deals can be very large, even though the technology is still at an early stage. Commonwealth Fusion Systems raised USD 860 million towards a demonstration plant planned for the early 2030s, and Helion Energy raised more than USD 400 million for a demonstration it aims to run by 2028.

Outside the United States, the largest deal went to Proxima Fusion in Germany, which raised USD 140 million.

3. Aviation

Aviation start-ups raised about USD 1.6 billion in 2025, up 57% from the year before. Most of this money went to electric aircraft.

Beta Technologies raised more than USD 300 million and Electra Aero raised USD 100 million, both in the United States. In hydrogen-powered flight, Australia's Hypersonix Launch Systems raised USD 46 million for a hypersonic aircraft concept.

Aviation was the largest of the seven areas before 2020, accounting for about half of their combined funding at the time.

4. Critical Minerals

Start-ups working on critical minerals raised about USD 1.2 billion in 2025, a record for the area. Many of them use data and artificial intelligence to find new deposits faster.

KoBold Metals in the United States raised USD 535 million and Canada's GeologicalAI raised USD 44 million, both combining geological data, satellite images and AI to speed up exploration.

Other deals focused on new ways to extract minerals. Cornish Lithium in the United Kingdom raised USD 45 million for lithium extraction, and France's Genomines raised USD 45 million to use plants to draw metals from the soil.

5. Next-Generation Geothermal

Next-generation geothermal start-ups raised nearly USD 1 billion in 2025, also a record. These companies use new drilling and engineering methods to reach heat deep underground in places where traditional geothermal power is not possible.

Eleven companies shared this funding, but it was highly concentrated. Fervo Energy in the United States raised about half of the total on its own.

Funding grew about 74% from 2024, the fastest rise among the seven areas after nuclear fission.

6. Heavy Industry

Heavy industry start-ups raised about USD 0.6 billion in 2025, a fall of around 20% from 2024. Most of the deals were for cleaner ways to make cement and steel, two of the hardest industries to decarbonise.

In the United States, Electra Earth and Terra CO2 raised a combined USD 300 million for steel and cement technologies. The figures in this ranking do not include chemicals, an area that raised significant funding before 2020.

7. Carbon Dioxide Removal

Carbon dioxide removal start-ups raised about USD 0.4 billion in 2025, down 37% from the year before. The area still drew a wide spread of companies, with 16 start-ups developing direct air capture raising money in 2025.

Switzerland's Climeworks raised USD 162 million, taking its total funding to more than USD 1 billion. In the United States, Aircapture raised its first USD 50 million, while Remora Carbon raised USD 60 million to capture carbon on board trucks and trains.

A Shift Away From Electric Vehicles

For years, electric vehicles and their batteries took a large share of energy start-up funding. That money is now falling as the industry matures and relies less on venture capital.

These seven areas have made up most of the difference. From 2015 to 2020, they took less than 5% of energy start-up funding; in 2025, they took more than a third.

New companies are following the money. Nearly 400 start-ups in these areas have been founded and funded over the past 10 years, and more than 60% of them were founded after 2020.

Big Projects, Patient Investors

Many of these technologies were once seen as a poor fit for venture capital. Reactors, geothermal plants and steel mills need large projects, long development times and hundreds of millions of dollars before they earn money.

Three of the six largest energy start-up deals of 2025 were for nuclear technologies. The report notes that specialist investors and large digital companies have provided much of this funding, though it is not yet clear whether this marks a lasting shift towards more patient investment.