LNG Design Gets Approval

Rolls-Royce and Canadian vessel designer Robert Allan have developed what they describe as the world’s first shallow-water push boat powered by liquefied natural gas (LNG) engines.

The classification society DNV GL gave its “Approval in Principle” to the new design, which will be powered by two MTU 8V4000M55RN natural gas engines from Rolls-Royce and designed for use on inland waterways.

Rolls-Royce and Robert Allan collaborated to design the gas-powered shallow-water push boat based on the Robert Allan RApide 2800-Z2 design, which is already used on some diesel-powered vessels on the Amazon. The vessel design was specially modified for LNG to accommodate the two 746 kW MTU 8V4000M55RN engines (complete with IMO Tier 3 emission control systems) and the entire LNG supply system – also available from Rolls-Royce – as well as the gas control and safety systems and the overall vessel control system.

The hull – externally unchanged – was redesigned to accommodate the 70 cubic meter gas tank as well as the usual engine accouterments. The lower crew cabins, saloon and galley were moved up one level, and the deckhouse was enlarged.

The Approval in Principle from DNV GL certifies that the design complies with the classification society’s rules for classification of maritime vessels and the international safety regulations for vessels using gas or other low-flashpoint fuels. It is an independent evaluation of the design concept within a given framework and states that the design is fundamentally feasible and there are no fundamental implementation concerns, the companies said.

DNV GL expects natural gas to cover over 40 to 80 % of all vessel propulsion power requirements by 2050. In addition, gas, where available, offers lower running costs, Rolls-Royce said.

Stefan Müller, who heads up the Marine & Naval Application Center at Rolls-Royce’s Power Systems business unit, sees the use of high-speed, pure gas engines like the MTU Series 4000 as offering great potential in ports, coastal applications and inland transportation. To unlock this potential, a reliable fuel supply infrastructure will be required.

“The interest of the market regarding the design study of Robert Allan and Rolls-Royce confirms that the decision was right to develop a lean-burn gas engine,” said Christof von Bank, director of Sales, Marine & Offshore Americas. “We have found operators across the globe who have seen the benefits of operational costs in addition to the reduction of environmental impact.”

Rolls-Royce will soon deliver its first MTU 8V 4000 M55N gas engines to municipal works company Stadtwerke Konstanz in southern Germany. These will be used to power the first LNG-powered car ferry on Lake Constance.