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A sea change for shipping efficiency

Sponsored by BP


BP is reducing the carbon footprint of its shipping fleet by making engines more efficient, streamlining hulls and even using LED lighting, says Gopal Hariharan

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The global shipping industry carries some 90 per cent of the world’s trade. But that comes at a cost. The industry also contributes around 2 per cent of global carbon dioxide emissions. So an important goal is to reduce that environmental footprint, an effort that requires a multi-pronged approach.

But this is no easy task. Ships have to operate in a wide range of extreme conditions, often for weeks or months at a time. Marine engines are complex to modify. And shipping fleets are expensive to change. So progress is hard.

Which is why the changes at BP Shipping are impressive. Engineers here strive to be at the forefront of efforts to find solutions that reduce carbon dioxide emissions.

And it has put those changes to work in its own fleet of ships. This fleet consistently meets, and often exceeds the benchmark requirements, such as the Energy Efficiency Design Index set out by the International Maritime Organization. BP Shipping continues to drive efficiency in the commercial shipping sector.

Gopal Hariharan, Engineering Manager at BP Shipping says: “At BP we are focused on making improvements to the efficiency of our ships. From the initial design of the ship to the technology that we have on board – we are aiming to reduce our carbon footprint wherever possible.”

Gopal-Hariharan

One example is the Mewis duct, a cylindrical channel with integrated fins that sits in front of the propeller. Whenever a ship moves through water, it produces a wake current that can be turbulent and so wastes energy.

But the Mewis duct guides this wake current towards the propeller. “It streamlines the water flow,” says Hariharan. At the same time, the fins inside the duct add a twist to this current before it reaches the propeller blades. That helps to increase the energy efficiency of the propulsion system.

BP also uses ‘self-polishing’ coatings on the hulls all of its ships. This prevents marine organisms latching onto the hull where they generate significant drag. By reducing this drag, the coatings help make the ships more efficient.

Other efforts to improve efficiency range from these sophisticated engineering solutions to things as simple as changing lightbulbs. “We have invested in LED lights, which use less electricity than traditional incandescent bulbs and also last longer, often for a decade,” says Hariharan.

Shipshape efficiency

These innovations have significantly reduced the fuel consumption and as a result greenhouse gas emissions of new oil tankers, compared to the ships they replaced in the BP Shipping fleet. This has resulted in approximately 21,000 tonnes of CO2 being saved in 2017. The fleet has been accredited as part of BP’s Advancing Low Carbon programme, which is designed to drive low carbon action across BP.

BP Shipping has also invested in a new fleet of liquefied natural gas (LNG) ships, the most fuel-efficient and technically advanced LNG tankers ever built for BP.

The ships are fitted with ‘slow speed’ tri-fuel engines, which use compressed ‘boil-off’ gas from the cargo tanks as fuel. Boil off is the LNG changing state to gas due to slight temperature rises during transportation.

“Because the tanks are carrying their liquid natural gas cargo at -162°C, gas vapour is formed with heat transfer from the atmosphere. This “boil-off gas” can then be used to power the engine,” says Hariharan.

The ships are also fitted with an exhaust gas recirculation system, which reduces nitrogen oxide emissions, and a gas combustion system that minimises the potential for releasing methane into the atmosphere.

This article appeared in print under the headline “Sea change”


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