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Turning Shipping Green

By Nicholas Newman energy journalist and copywriter

Under The International Maritime Organization’s regulations, ships built after 2025 will be 30 percent more efficient, with better engines, cleaner fuels and smarter speed management. In anticipation, ship designers, builders and engine manufacturers are currently working on improving energy efficiency with a new engine, hull and propeller design, exhaust gas by-pass systems, ballast water treatments and speed control systems for pumps and fans. Engineers and designers are working on the aerodynamics of rigs, kites and trims to improve a ships’ energy consumption and reduce pollution. Ship owners are turning towards fuel decarbonisation, employing low-sulfur and LNG fuels as well as scrubbers to minimize emissions.

A fuller catalogue of the measures currently underway should make interesting reading for anyone concerned with environmental issues, whether inside or outside the maritime industries.

Alternative Fuels- to cut emissions on water and in dock

·        More costly, and still only a niche segment is the use of Liquid Natural Gas (LNG) as a main or auxiliary source of fuel. A small, but increasing number of vessels are fuelled by LNG including ferries owned by Tallink Grupp AS, cargo ships operated by TOTE on the Miami Florida run and LNG carriers owned by Teekay. LNG fuel has 20 percent lower GHG emissions and between 85-100 percent noxious gases compared with HFO. Dual -fuelled engines to accommodate LNG as an auxiliary fuel, are now available and Wärtsilä has just completed trials of the first hybrid energy storage solution installed on The Viking Princess, a LNG fuelled offshore supply ship, which could save up to 30 percent in fuel and reduce CO2 emissions by 13-18 percent a year, depending on operating conditions.

·        For ships relying on Heavy Fuel Oil, but entering low emission waters, attaching a sulphur scrubber system to the ship’s exhaust reduces SOx emissions by 98 percent and is a cost-effective investment. Yarra Marine Technologies based in Norway provide scrubbers.

·        Sail and Kite Propulsion Systems used alongside conventional systems are especially environmentally friendly reducing fuel and NOx, SOx and CO2 emissions by 35 percent.  3,000 ships are forecast to have Skysails by 2020.

·        Shore-to-ship-power provides electric power to ships at berth allowing main and auxiliary engines to be shut down whilst in port, therefore eliminating air pollution and reducing risks to the health of nearby residents and workers. Power technology provider ABB has installed electric supply facilities for cruise liners and cargo ships docking at the Ports of Gothenburg in Sweden and Vancouver in Canada.

Technological applications

Inside the National Maritime Museum at Greenwich London

·        To tackle greenhouse gas emissions, fuel-efficient engines and propelling systems seem to offer the most promising technologies.

·        Modern waste-heat recovery systems help reduce a ship’s fuel consumption by up to 14 percent because exhaust gases from the engine can be recycled to heat and generate steam for power and heating.

·        Exhaust Gas Re-circulation, as supplied by Perkins Engines, reduces NOx emissions by up to 80 percent. This mixes exhaust gas from the engine cylinder with scavenging air to lower temperature in the combustion chamber where, a portion of exhaust air is re-circulated and added to the scavenge air of the engine, reducing both the oxygen content and temperature of the combustion cylinder.

·        Adding water to the fuel before injection into the combustion chamber can reduce NOx emissions by between 30-35 percent whilst improved Pump and Cooling Water Systems can reduce electricity consumption by 20 percent and fuel by 1.5 percent.

·        To keep an empty ship stable, seawater, along with unwanted sediment and micro-organisms, is customarily pumped into ballast tanks, thus incurring a biohazard risk. Marine engineers Cold Harbour’s ballast water cleaning system is already employed on ships in the Great Lakes of North America. For new builds, designers are focusing on reducing and even eliminating, the need for ballast tanks.

·        Developments in marine paint have already cut air pollution and fuel consumption by 3 and 8 percent respectively.

Improving Command and Control Systems


·        Innovations in the design of rudder and propeller systems are important contributors to incremental improvements in fuel efficiency and reductions in air pollution.

·        Adding Damen Marine Component’s speed nozzles to propellers help reduce water drag and improves fuel efficiency.

·        Electronically controlled engines improve speed management and are helpful in reducing NOx emissions.

In sum, this array of improved designs, technological innovations and alternative fuels are combining to produce a virtuous circle of significant reductions in energy consumption and emissions of CO2 and noxious gases.


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