Joule is an emerging California-based clean energy startup developing the next generation of ocean-based energy storage. Our mission is to make large-scale renewable storage practical, affordable, and globally deployable.

Fun Fact:
A joule is the scientific unit of energy - equal to the work done when one newton of force moves an object one meter. In other words, it is a measure of the power that drives motion, light, and life itself.

Joule’s patented Modulated Buoyancy Energy Storage (MBES) system is a cutting-edge cleantech solution designed to store excess energy from renewable or conventional generation. Positioned beneath the ocean’s surface, MBES stores energy efficiently and releases it back to the grid when demand rises.

The MBES system uses a Modulated Buoyancy Unit (MBU) - a sealed structure connected vertically between a surface buoy and an anchor base. To store energy, compressed air is used to neutralize the MBU’s buoyancy, causing it to sink. When energy is needed, air is reintroduced, restoring buoyancy and allowing the unit to rise. This motion drives a generator that feeds clean electricity back into the grid.
The system requires no land, freshwater, or hazardous materials, and can be deployed near offshore renewables or coastal infrastructure.

Global renewable generation is growing faster than our ability to store it. Without storage, energy is wasted through curtailment, especially in wind and solar projects. Ocean-based systems like MBES offer vast scalability, low environmental impact, and strong alignment with national security and energy independence goals.

We’re selective about our investors, seeking partners who share our mission and long-term vision for global energy resilience.

To explore opportunities, visit our Investment page and complete the form to connect with our team.

We’re seeking pilot partners with deep water access and a grid interconnect, such as offshore wind, solar, or wave operators - to help demonstrate MBES scalability and economics.

Learn more and apply on our Pilot Partner page.

We’re assembling a world-class team of engineers, scientists, and innovators who believe in shaping a sustainable future.

If you’re ready to help build the future of energy storage, visit our Join the Team page.