LNG is becoming an increasingly important fuel source for the shipping industry, which must meet new environmental requirements within the decade. This year’s NOR Shipping conference in Oslo highlighted LNG’s significance with the unveiling of DNV’s and Oshima’s ECO-Ship concept and the Next Generation award to Rolls-Royce Marine for its Environship.
The shipping industry globally has become more aware of the need for environmentally friendly vessels, particularly those powered by liquefied natural gas (LNG). All newbuilds after 2016 will have to meet very strict standards for sulphur emissions. LNG will then be best the best solution for new builds from that time, according to Erik Dyrkoren, MARUT secretary and programme manager for the industry’s Maritime 21 strategy.
Norway is the only country that has an LNG powered fleet and a good vantage point for making an industrial impact. There are almost 30 Norwegian vessels in its waters running on LNG and another 20 on order, largely thanks to the industry initiative called the NOx Fund (see separate article), says Dyrkoren. The membership-based affiliation allows companies to pay a participant fee instead of paying nitrogen oxide taxes.
“The technology is basically available but it is a matter of getting the ship owners to do the investment,” he said. “But that’s changing. We see shipowners are now looking ahead at a much higher price on bunker oil, making LNG even more attractive.”
One such forward thinking collaboration is Oshima Shipbuilding of Japan’s teamwork with Det Norske Veritas in developing the LNG-powered ECO-Ship concept. The two announced at NOR Shipping in May that they had reached the first milestone in their open hatch bulk carrier concept, which they anticipate will emit half the CO2 emissions compared to a traditional bulk carrier of corresponding type and size.
The main part of the economic savings will be achieved through reduced voyage costs. Currently, the price of gas is lower than oil, making it more cost effective to power these carriers’ long voyages through LNG.
“Heavy fuel oil has earlier been cheap compared to the current high levels and there has not been much focus on emission requirements,” said Adam Larsson, DNV project engineer for ship hydrodynamics and DNV’s project manager for the ECO-Ship project. “Now there is more interest on emissions reduction and thus interest for environmental-friendly ship designs such as the ECO-Ship is growing.”
By using LNG as a fuel source, the ECO-Ship will be able to emit about 20% less CO2 than oil powered vessels thanks to the switch to lean burn gas engines. Once the design savings are implemented on-board in combination with the ship’s operational profile, the total amount of reduced CO2 emissions would be closer to 50% on a tonne-mile basis, according to Larsson. In addition, LNG practically does not contain sulphur and the LNG combustion process emits 90% less NOx and eliminates all particulate emissions.
A significant part of the environmental savings come from the highly efficient propulsion system running on LNG, based on Rolls-Royce’s lean-burn four-stroke medium speed gas engines and a flexible propulsion and power generation system. The concept ship also features a waste-heat recovery system that can feed electric power into the system to supplement ship propulsion power, giving about 5% additional fuel savings at normal cruising speeds.
LNG propulsion is just one element of the ship’s many technical advances. For example, the design speed has been lowered compared to typical open hatch bulk carriers for additional fuel savings. The reduced design speed allows for a wide hull form and twin screw propulsion system with high propulsive efficiency. Some of the improvement areas here include an air lubrication system for less hull friction, use of Oshima’s Seaworthy Bow for less resistance in waves, and flipper fins to improve the hydrodynamic flow to the propeller.
Next Generation Award
Another type of LNG technology that was recognized at this year’s NOR Shipping conference was Rolls-Royce’s Environship concept, a general cargo ship that has been optimized to carry a combination of cargo typical for short sea shipping in Northern Europe. The concept was awarded the Next Generation Ship Award, which recognizes the yard, designer or owner with the most promising idea that will be at sea in the coming decade.
The Environship uses a Rolls-Royce Bergen B-Series lean burn engine that emits about 17% less CO2 per unit of power than a diesel engine. The use of gas fuelled engines means that NOx emissions are reduced by about 90% while sulphur oxide (SOx) emissions are negligible. The short sea shipping fleet is ageing and in need of renewal. By swapping to LNG fuel, the emissions from the shipping segment can be significantly reduced.
The company received its first order for vessels based on the Environship concept in October 2011 for Stavanger-based Nor Line. Rolls-Royce will design and provide integrated power systems for two technologically advanced cargo vessels to be built in China for start of operations along the west coast of Norway in 2013.
The ships feature a striking wave piercing bow, gas-powered engines, and Promas propulsion system, which combined increase fuel efficiency by up to 18%. The Promas system is an integrated rudder and propeller, while the vertical bow shape enables the vessel to maintain speed even in rough seas with burning additional fuel to make up for lost time.
“Nor Lines and its owner, Stavangerske Dampskibsselskab, believe that the future fuel for ships is natural gas,” said Toralf Ekrheim, Nor Lines chief executive. “In relation to oil-powered ships, the two new Nor Lines ships will have more than 35% lower greenhouse gas emissions.”