The naming ceremony of Energy Observer, the first hydrogen-propelled, energy self-sufficient vessel, with zero CO2 and particle emissions, will take place on 6 July in Paris, before the vessel sets out on its six-year round-the-world voyage. In 2015, the Energy Observer team entrusted CEA with the task of designing the vessel’s energy system, the only one of its kind in the world, bringing together various energy sources, including high-efficiency solar panels, electrolyser, fuel cell and batteries. Since then, research engineers have worked on designing and optimising the entire energy generation and management system, right through to the propulsion system. 

Energy Observer showcases a 100% renewable energy mix, combining solar, wind and hydro energy, coupled with a hydrogen storage system using lithium-ion batteries, as well as a complete hydrogen system. This outstanding technological feat is the result of twenty years’ R&D at CEA-LITEN (Laboratory for Innovation in New Energy Technologies and Nanomaterials ). CEA-LITEN intends to prove the maturity of the embedded technologies and the potential of energy mixes and renewables for a clean, efficient and innovative future.

The Energy Observer team of crew members, naval architects and thirty or so engineers from CEA-LITEN had many challenges to face. As well as meeting the objective of complete self-sufficiency and zero emissions, technologies had to be adapted to the rather hostile environment at sea, with salinity, humidity and swell, for example. An added constraint was the actual architecture of the catamaran, as the various parts of the energy system had to be installed in areas that are narrow and hard to get to.   Equipment weight is another problem: the lighter the vessel, the less energy it consumes. In the end, the entire energy system weighs in at 1.3 tonnes, compared with the 30 tonnes that could normally be expected for this type of installation.
 
Details of the energy systems developed by CEA

Solar energy – Two different technologies were used to make the 120 square metres of solar panels. The made-to-measure panels covering the deck are curved so that they hug the rounded hull. The bifacial panels with heterojunctions are designed to capture direct sunlight as well as the light reflected by the water and the boat. They are installed aft and along the entire length of the hull. 
 
Storage - The lithium-ion batteries will be used for short-term storage and will supply two separate power systems - one 400 V and one 24 V. The first is used to manage power demands, propulsion, electrolysis and hydrogen compression; the second for life on board and for instrumentation and control and safety equipment.

A complete hydrogen system will be used for long-term storage. For this purpose, Energy Observer is equipped with a desalination system, an electrolyser, tanks and a fuel cell. This system will produce hydrogen from sea water, store it on board and use it to power the fuel cell. Electrical energy from the fuel cell will be fed back into the circuit, while reaction heat will be used to heat domestic water on board.
 
Complete system management - In addition to the equipment for capturing and storing energy on board the catamaran, CEA-LITEN’s teams developed the system for managing and monitoring the entire energy system. The goal is to ensure optimum operation according to resources, which vary depending on time of day and weather, and to the vessel’s itinerary. All the navigation data will be analysed in real time by the engineers in order to propose suitable scenarios.

Photo: Energy systems of Energy Observer (credits: CEA / Energy Observer)

Three operating modes

When the boat is berthed, it does not consume any energy apart from what is needed on board. The solar and wind energy is used to recharge the Li-ion batteries. All the surplus energy goes to the electrolyser production and hydrogen storage system.

In favourable sailing conditions, generation and consumption are evenly balanced. The batteries are used to cover power demands and intermittency management for the various energy sources. While the smart kite is in use for long crossings, the propeller will go on turning and act as a dynamo and, in fact, become a hydrogenerator with its reversible motors.

When solar and wind energy is not enough to meet demand, the fuel cell, running on the stored hydrogen, provides the boat with yet more energy.

Source: CEA

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