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Energy Observer has one stopover left in Saint Pierre and Miquelon, a French territory off the Canadian coast of Newfoundland, before crossing the North Atlantic to withdraw.
The Energy Observer, a catamaran powered by solar and wind energy, is nearing the end of its extensive global voyage, having sailed more than 64,000 nautical miles circumnavigating the globe. The vessel has demonstrated the viability of maritime travel powered by renewable energy, even in the most difficult ocean conditions.
Last week, pv magazine US met with Energy Observer systems engineer Luc Bourserie in Boston Harbor. This 30-meter-long boat works with a sophisticated energy system that uses solar and wind energy, storing long-term energy in hydrogen and short-term in batteries.
The Energy Observer features 202 square meters of Solbian flex modules and newer bifacial modules. With a nominal power of just over 33 kW, the actual maximum power of the panels is around 26 kW due to their placement at a fixed angle throughout the warehouse, which optimizes maximum cumulative power rather than maximum efficiency.
At one point, the solar panels needed to be upgraded. Initially, the vessel was equipped with hard-structured bifacial glass modules. Splashing water from the ocean forcefully broke some of the panels installed in front of the solar fins, so they were replaced with custom-made single-facial flexible panels. The bifacial panels that remained intact were kept at the rear, where reflection has the greatest impact.
The design team chose Solbian flexible modules for their adaptability and durability and found them to be an ideal choice for curved surfaces, and their availability in various shapes and sizes ensured coverage of almost any area. Additionally, the modules are sturdy enough to be walked on, a crucial feature for the ships tight spaces.
The ship uses 13 DC-to-DC converters, each 3 kW, manufactured by Switzerland-based e-mobility specialist BRUSA Electronik AG. These converters increase the solar output voltage from 20 to 30 volts up to the 400 Vdc required by the main 100 kWh lithium nickel manganese cobalt oxide (LiNMC) batteries used for propulsion and the 24 Vdc battery and 20 kWh used for control systems. The converters are equipped with maximum power point tracking (MPPT) controllers that optimize the conversion efficiency of the solar modules under various lighting conditions.
In high winds, the Energy Observer can harness additional energy by driving its propellers (in reverse), turning them into turbines that generate energy. The ships innovative sails, known as Oceanwings, were first tested on this vessel and have since been adopted by the Canopée, a French container ship that transports rockets across the Atlantic. These sails reduce fuel consumption by up to 30% compared to traditional diesel vessels.
According to Bourserie, the Oceanwings automatically adjust to maximize energy harvesting. These prototype sails have required continued development and some replacement components to withstand the rigors of maritime conditions.
The vessel is equipped with an innovative hydrogen storage and compression system that stores hydrogen at 350 bar in eight composite tanks, using a two-stage compression process developed with Nova Swiss to manage the transition from 30 bar (the outlet pressure of the electrolyzer) at 350 bars. Tanks offer a higher energy-to-weight ratio than batteries, storing ten times the energy at half the weight, and multistage compressors are much lighter than traditional models designed for fixed stations. This allows up to 62 kg of hydrogen to be efficiently compressed and stored.
The 62 kg of hydrogen stored on board can power the ships fuel cells for about six days, providing 1 MWh of electricity and 1 MWh of thermal energy. Supplied by Toyota, the batteries are a modified version of those used in the companys Mirai vehicle.
While traveling more than 64,000 nautical miles, the Energy Observer generally sailed close to the coasts. However, she also undertook several important open sea voyages across the Atlantic, Pacific and Indian Oceans. These segments taught the crew how to strategically manage their energy resources.
For example, Bourserie explained to pv magazine United States , on days with good conditions - strong sun and wind that allows them to avoid the use of engines - “we do not do electrolysis in navigation, [since it is about] protecting the compressors, and also the excess energy would not be so much. To continue harvesting energy from the sun, we cook in the afternoon for the night or use the washing machine, producing fresh water from sea water at that time.”
On CNET, naval scientist Katia Nicolet stressed the daily importance of energy management on board. The crew often had to consult Bourserie about energy use, with questions like, “Can we run the dishwasher? Can we eat hot tonight or are the batteries too low?”
The crew also faced unique challenges arising from the COVID pandemic, including a long period of more than 45 days without docking, which demonstrated the resilience and self-sufficiency of both the crew and the ships renewable energy systems.
As the Energy Observer prepares for its final Atlantic voyage from Saint Pierre and Miquelon, it is a testament to the potential of renewable energy to power our future on the seas. |
