The Manta will be the "first user boat capable of collecting and enhancing large quantities at sea" of floating plastic waste.Presentation of this catamaran which must be put in the water in 2024.
A collection of 5,000 to 1,000 tonnes of plastic waste per year
"Each minute, 17 tonnes of plastic waste is poured into the oceans...Or 9 to 12 million tonnes each year, ”recalls The Seacleaners. Cette association, créée par le navigateur franco-suisse Yvan Bourgnon(1), ambitionne de construire un « bateau nettoyeur des mers, capable de collecter de manière industrielle des déchets plastiques flottants […] aussi bien les macrodéchets que les débris plus petits à partir de 10 millimètres et jusqu'à un mètre de profondeur ».
Called "Manta", this future ship should measure 56.5 m long and 26 m wide, with a tiering of 3.1 m. Pouvant accueillir 34 personnes à son bord (dont 22 membres d’équipage), il pourra naviguer à 6 nœuds en moyenne mais circulera à basse vitesse – 2,5 nœuds au maximum -lors de la collecte de déchets plastiques afin de permettre aux « mammifères marins, tortues en respiration à la surface, poissons adultes de se sauver en sondant/en plongeant »(2) (d’autres dispositifs sont par ailleurs prévus pour ne pas perturber la faune et détecter les poissons).
Three waste collectors will be located at the rear of the ship: "a central and two laterals which will be towed by two tanges on each side of the boat" (46 m total).Rolling carpets located "under the ship's platform, between the hulls" will transport the collected waste which will be manual sorting on the catamaran (by 3 people).Two small boats on the back of the giant catamaran can also recover waste "in narrower, shallow and less accessible areas, where maneuverability is limited" (these boats must be deployed independently from 2021).
In total, The Seacleaners evokes a manta collection capacity of 1 to 3 tonnes of plastic waste per hour, which should allow the ship to "rid the oceans from 5,000 to 10,000 tonnes of plastic waste per year".In other words, it would take approximately a thousand Manta ships sailing 300 days a year to capture the annual volume of plastic waste dumped in the oceans at the current rate.
An energy autonomy "75% of the time on average"
But the Manta will not just collect plastic waste: it will value "95% to 100%" of them on board, "thanks to an energy conversion unit by pyrolysis".During the sorting of waste, those in metal, glass or aluminum will be stored for land recycling while those in plastic will be crushed and compacted on site before feeding a "Wecu" unit (Waste-to-Electricity Unit Conversion) of 100 kW. Le plastique y sera transformé en gaz de synthèse par pyrolyse(3)et ce « syngas sera lui-même converti en électricité » à bord du Manta.
The electricity produced will help feed the hybrid propulsion system of the ship "combining 1,500 m² of sails installed on automated rigging and electric propulsion motors". Outre la valorisation de déchets plastiques, l’électricité fournie aux moteurs sera produite par deux éoliennes à axe vertical de 100 kW situées à l’arrière du bateau, deux hydrogénérateurs de 100 kW chacun sous le navire et environ 500 m2de panneaux photovoltaïques installés à la proue du navire de 100 kW de puissance crête.Note that a third of the photovoltaic surface will be located on retractable wings that will strengthen the pace of the vessel of the ship.
In total, this will allow the ship to "operate 75% of the time on average independently" (more when the manta is powered by sails, sometimes less when the factory will operate at full capacity).Manta will have two diesel engines for remaining energy needs.
Towards a launch in 2024
According to the current calendar, The Seacleaners will finish in 2021 the consultation of shipyards for the construction of the MANTA and will carry out certain exploratory campaigns to specify the first missions of the.The start of the construction of the catamaran was envisaged in 2022 for a launch and the first collection missions in 2024.
Manta will sail "mainly in Asia, Africa and South America, in strategic sectors where marine plastic pollution is particularly dense: coastal areas, rivers, mouths of large rivers and estuaries", specifies The Seacleaners.
The MANTA construction cost is estimated at nearly 35 million euros.To date, the project has had no public subsidy and is based on the private funds of around fifty patronage companies (The Seacleaners is currently continuing to find funding).
Like the Energy Observer hydrogen ship, the MANTA aims to become an "boat-ambassador" of the ecological transition and will carry out educational actions on plastic pollution and the circular economy (by presenting innovative technologies during itstrips and welcoming the public on board in particular), while also contributing to scientific missions.
