Swedish tanker operator Stena Bulk has created a design for a product / chemical tanker partly powered by wind and solar power, which it calls IMOFlexMAX.
It estimates that the vessel will be able to reduce CO2 emissions by at least 25 per cent, “with a potential to reach up to 45 per cent” compared to a modern product tanker on low sulphur fuel oil.
It has been designed by naval architects at sister company Stena Teknik and is based on 40 years of tanker shipping experience.
The wind driven propulsion comes from Flettner motors. These are cylinders which are spun along their long axis (driven by electricity or connection to the ship’s engine).
The propulsion force comes as air passes across the cylinder, due to the “Magnus effect,” the force generated by fluid flow over a rotating body.
The ships are also equipped with solar panels.
They are powered by dual fuel engines, running on both LNG and low sulphur liquid fuels.
The design builds on experience with Stena’s “IMOIIMAX” vessel design, which has improvements to the “hull lines”, engines and propeller, to create a design for what the company believes is “the most energy efficient ECO MR tanker existing today”. It has auxiliary engines optimised for part load operation (rather than being optimised for high load operation, which is usual). It has two separate boilers for heated cargoes. When less heat is required, it can be more efficient to have one smaller boiler at full capacity than a large boiler at half capacity.
The vessel is also able to recover heat from exhaust gas.
It uses nitrogen instead of flue gas for inerting tanks, which the company says is more fuel efficient, as well as making for easier cleaning.
13 IMOIIMAX MR tankers were in operation as of January 2020.
“The plan is for the IMOFlexMAX vessels to be deployed in Stena Bulk’s logistics system in the global market along with the IMOIIMAX,” says Erik Hånell, president and CEO of Stena Bulk.
“IMOFlexMAX vessels will constitute an important asset for Stena Bulk, as well as for its partners, in strengthening our position as the market-leading, cross-trading specialists in the MR segment with increased efficiency and reduction of greenhouse gases.”
“The prototype is one step further in Stena Bulk’s vision of being our customers’ first choice for safety, innovation and performance in the transportation of oil, chemicals and gas.”