blog icon

Energy Currents
A Blog by Enerdynamics

Meet the Energy Observer, the World’s First Hydrogen-powered Boat and Trailblazing Energy Laboratory

by Christina Nagy-McKenna, Enerdynamics Facilitator

Four years ago, the Energy Observer left Saint Malo, Brittany, for a seven-year voyage across the world. The French catamaran’s mission is threefold: create innovative technologies to accelerate the use of renewable resources; meet other global, environmental pioneers; and educate people about the challenges of clean energy and environmentalism through exhibitions at stopovers along the way.

The journey is adventurous, daring, and revolutionary. The zero-emission Energy Observer is as much a research laboratory as it is a boat. It tests clean energy technologies, including wind, solar, and hydrogen power, in conditions that can be hostile and turbulent. Roughly 35,000 nautical miles into its journey, the boat has navigated around the Mediterranean, up through Northern Europe, across the Atlantic Ocean, through the Panama Canal, and up the Pacific coast. This week it begins its next adventure: a voyage across the Pacific Ocean with a stop in Hawaii and then on to Japan in time for the 2021 Summer Olympics.

The boat is powered solely with three primary renewable energy sources – solar, wind, and hydropower. Due to the intermittency of renewable power, storage is provided by lithium-ion batteries and hydrogen tanks. When all the renewable energy is not needed for propulsion or other uses, the excess is used to charge batteries or make hydrogen from sea water using the excess energy to power hydrolysis. The hydrogen is later used as needed to generate electricity using fuel cells.   

The Energy Observer has a diverse, cutting-edge energy system that has been upgraded several times during scheduled maintenance stops. The solar array includes 202 square meters of solar panels that can generate a maximum of 34 kWp, or kilowatt peak performance. On average the panels generate 120 kWh per day, which is enough power to meet the needs of nine homes[1]. In 2019 some original panels were replaced with newer, anti-slip ones, a useful additional for a catamaran. In 2020 the crew added additional panels to the boat and increased its peak capacity. The solar panels provide enough power to run the 42 kW-capacity electric motors and for the crew’s ancillary needs such as lighting, heating, kitchen appliances, and a washing machine.

In keeping with its goal of testing the newest and most innovative technologies, the Energy Observer replaced its original wind turbines in 2019 with two Oceanwings®, vertical wind propellers with 12-meter wingspans. The new sail-like propellers increase the boat’s speed, reduce energy consumption, and produce hydrogen through electrolysis. Previously the boat could only produce hydrogen when in port due to the sizable energy needs of the electrolyzer.

Perhaps the most impressive technical aspect of the Energy Observer is its hydrogen power system. While the boat stores some excess energy in lithium-ion batteries, the majority of the surplus energy is stored as hydrogen gas. A desalinator purifies salt water before an electrolyzer separates the hydrogen and the oxygen. The hydrogen is stored in eight lightweight tanks made of carbon fiber and aluminum until it is needed for the two fuel cells. Using hydrogen as a storage medium instead of heavier lithium-ion batteries saves a considerable amount of weight, which translates to a quicker boat that uses less energy. The hydrogen fuel cell system was built by Toyota using components that it employs in its hydrogen-powered Mirai vehicle. The Rex H2, known formally as the Range Extender H2, was created specifically for marine applications and will continue to be tested by the Energy Observer as it journeys home over the next three years.

As it did with many people’s plans for 2020, the COVID-19 global pandemic threw a wrench into the original plans of the Energy Observer. Not unlike all of us, the boat ’s crew had to pivot and change long-standing plans, such as visiting California, Hawaii, and Japan (in time for the previously scheduled 2020 Olympics). Unlike most of us, however, the crew was also faced with not being able to dock at all ports as previously planned and often not being allowed to disembark the boat. The ability to generate all of its power through renewable, self-sustainable sources helped the crew as it had to stretch its resources. Back on track in 2021 as it sails across the Pacific, the Energy Observer will continue to create, test, and upgrade renewable energy technologies while learning from experts it meets along the way and educating audiences about sustainable, green energy technologies.

To follow the progress of the Energy Observer, look for the vessel on your favorite form of social media, its YouTube channel, and their web site:

Footnotes and Bibliography

[1] Energy Observer Press Kit, March 2021.

Margones, Stas, “Port of San Francisco Greets Zero Emission ‘Energy Observer’,” May 11, 2021,,

Stewart, Jack, “The Funky Boat Circling the Planet on Renewable Energy and Hydrogen Gas,” July 5, 2018, Wired,

Verdon, Michael, “This 100-Foot Catamaran Just Crossed the Atlantic Using Only Hydrogen Fuel and Solar Power,” May 11, 2020, Robb Report,

“Energy Observer, the First Round the World Hydrogen-powered Vessel About to Arrive in California!”, April 8, 2021, Mission pour la Science et la Technoligie, Ambassade De France Aux Étas-Unis,

Back to Energy Currents blog


Solar power , Zero emissions , Wind power , Clean hydrogen ,