After helping rockets find their way to outer space, Andrew Redd is now looking deep in the ocean. The SpaceX alum has raised $54 million for his startup Endurance Energy to harness a massive untapped energy source — the heat stored in the world's oceans.

Redd grew up in the Pacific Northwest, a region hit by uncharacteristic heat waves and catastrophic fires in recent years. That experience pushed him toward renewable energy after his stint at Elon Musk's rocket company.

The technology is called ocean thermal energy conversion (OTEC). It works by exploiting the temperature difference between warm surface water and cold deep water. That温差 drives a turbine to generate electricity, similar to how a steam engine works — but using ocean water instead of boiling coal.

The $54 million funding round was led by climate tech investors, including several undisclosed venture capital firms. Endurance Energy plans to use the money to build its first commercial-scale plant, likely in tropical waters where the temperature gap is biggest.

OTEC isn't new — scientists have known about it since the 1880s. But previous attempts failed because the technology was too expensive and inefficient. Redd's team says they've solved those problems with a new turbine design that works at lower temperature differences, making it cheaper and more reliable.

The potential is enormous. The oceans absorb about as much solar energy each day as the energy contained in all the world's oil reserves. If even a fraction of that could be converted to electricity, it would dwarf current renewable sources like wind and solar.

But OTEC faces big hurdles. The plants are expensive to build, require deep underwater pipelines, and can only be located in tropical regions. Environmentalists also worry about disrupting marine ecosystems by pumping up cold water from the deep.

Redd acknowledges those challenges but says the climate crisis demands new solutions.

Endurance Energy has already tested a small-scale prototype off the coast of Hawaii. The next step is a 10-megawatt plant that could power about 3,000 homes. If that works, the company plans to scale up to 100-megawatt facilities within a decade.

For context, the entire global OTEC industry today produces less than one megawatt — mostly from experimental plants in Japan and South Korea. Redd's $54 million bet is the largest private investment in the technology to date.

The funding round closed on June 10, 2026. Redd declined to disclose the valuation but said the company is now valued at over $200 million.

The oceans absorb solar energy equivalent to all oil reserves daily. Endurance Energy's first commercial plant is planned for 10 megawatts, enough for about 3,000 homes. Current global OTEC output is less than 1 megawatt.