A low, spaceship-like vessel will wind its way up the U.S. Atlantic coast from New York to Boston and onward this week, part of a solar-powered journey along the Gulf Stream that will end in Bergen, Norway. The MS Tûranor PlanetSolar, with its prominent span of photovoltaic panels, obviously aims to be a bellwether for renewable energy’s potential, and it has broken records as a solar boat. Now the striking catamaran has a new role, ferrying scientists who hope to capture new data about the ocean that will help deepen our understanding of climate change and weather.
PlanetSolar docked in New York City Monday, eking a passage into its narrow marina spot in lower Manhattan and overcoming an unexpected snag on some rope underwater. Having traveled from France via Miami, its general itinerary northward is mapped out, but concessions must be made considering that the boat’s sole source of power is the sun. “[On any boat] we’re used to computing the wind, the state of the sea, and the current, but now we have to add a new parameter, which is the sun,” said the vessel’s captain, Gerard d’Aboville, who receives solar forecasts that look ahead to the next several days. “Then I have to make the route considering the sun exposure. Sometimes the shortest way from A to B is not a straight line,” he said, laughing.
PlanetSolar is not the only solar boat out there, but it is the largest, and the first to circumnavigate the globe. Like the Solar Impulse plane that is now concluding a cross-country journey in the U.S., PlanetSolar hails from Switzerland. The project began in 2008 as a venture between Swiss engineer-adventurer Raphaël Domjan and German investor Immo Ströher, who wanted to build a model of clean energy for the sea that could also be viable commercially. About 100 feet long with a span of about 75 feet, the catamaran gets its power from 5,662 square feet of solar panels installed on its deck and fins. Those panels feed 8.5 tons of lithium-ion batteries.
D’Aboville said PlanetSolar can sail for about 72 hours on battery power if there is no sun. Running at a lower speed also slows the rate at which the batteries will drain. He noted that founder Domjan could have built a much lighter and faster boat, but that PlanetSolar’s team decided to make the boat heavier so it could have a longer life accommodating research expeditions like the one currently under way.
The trip, billed “Deepwater Expedition,” is being led scientifically by University of Geneva’s Martin Beniston, a professor and head of the school’s Institute of Environmental Sciences. His team, which includes a regular rotation of students from the university, will take water and air measurements along the route that they hope will refine understanding of the ocean’s role in climate.
“We know broadly how the Gulf Stream functions and its role in thermal regulation of the atmosphere on both sides of the Atlantic,” Beniston said. “We know less about what’s going on in some of the smaller scale features” such as ocean vortices, the below-surface whirlpools that transport thermal energy to places where the Gulf Stream does not reach.
Beniston’s team also plans to measure aerosols given off from the ocean: the fine particles rising from the water’s surface are poorly understood, he said.
“We estimate that between one half and two thirds of aerosols [released into the atmosphere] are actually released from the ocean. Of course, you have aerosols of industrial origin, like soot and sulfate and things like that that we know about, but from the ocean it’s much more difficult to have an overview of what’s going on,” he said.
Aerosols have different effects (some reflect sun, cooling the atmosphere; others trap heat) depending on their type and where they are released, and they may vary depending on the originating water mass. NASA’s Goddard Institute is also studying the effect of aerosols, and provided the PlanetSolar team with an instrument to help collect data for its own work.
Taking measurements from a vessel that emits no pollutants means the team can, ideally, collect unadulterated information about the air just above the sea. “This is something fairly new, fairly unknown, and we hope to get some exciting results,” Beniston said.
The PlanetSolar expedition will also study microorganisms, including phytoplankton that become airborne via ocean aerosols, and their relationship to warming. Bastiaan Ibeling, a professor of microbial ecology from University of Geneva who is also on board, noted that phytoplankton, which act as carbon sequesterers, are already being affected by climate change. Water that is being warmed at the surface by higher temperatures, along with freshwater from melting ice, “floats like a blanket” on colder water below, he said, making it difficult for phytoplankton to bridge the gap between life at the surface and necessary nutrients deeper down.
The expedition will end in August, after which PlanetSolar will embark on a plastic waste collection campaign in European waters. Meanwhile, the researchers from Deepwater Expedition hope for some preliminary results to share this summer, and a more formal publication of its findings afterward.
Do PlanetSolar’s technical energy accomplishments have wider applications for boating? Perhaps not anytime soon. “I think this boat is a kind of demonstration of what you can do with solar energy,” said the captain, d’Aboville, who has had involvement with the boat since its 2010 voyage around the globe. “I consider this boat as an ambassador.” Instead, PlanetSolar’s legacy may lie within the climate science it is now powering.