Dual fuel shipping: natural gas with a hint of diesel

There is a lot to be gained from cleaner shipping. We've looked at the international policy dimension in an earlier article. The Dutch government is particularly interested in making inland navigation more environmentally friendly. It can learn from off-shore, mainly Norwegian shipping experiences with liquefied natural gas (LNG).

Geographic
LNG shipping can constitute lasting air quality improvement. Norway has been exploring the possibilities for a decade already, in off-shore shipping, in car ferries and, more recently, passenger ferries. Apart from a few false fire alarms because of fog around the hoses attached to fuel storage units, caused by the extremely cold LNG passing through the hoses, there have been no complaints about the ferries.

Norway has large national gas reserves and, for geographic reasons, a strong maritime tradition, which explains the use of LNG to fuel ships. Both conditions are also true for the Netherlands, so it was only a matter of time before the Dutch would have their own LNG ship premiere, which they will next year.

Argonon
If all goes well, the LNG-powered 'type C' tank vessel Argonon will be ready in 2010. By 2016 it must be cost effective and complient with the Central Commission for Rhine shipping emission regulations (CCR4) then in effect. Deen Shipping, together with International Naval Engineering Consultants INEC and Pon Power, a Caterpillar and MaK engine distributor, are receiving government funding for this project within a 5.5 million euro inland shipping innovation programme.

The Argonon, which will boat on the River Rhine, will be a dual fuel ship. It will have an LNG storage unit on it, with enough capacity to go from Rotterdam to Basel, Switzerland, and back without refuelling.

Gas-only versus dual fuel
Most Norwegian ships run on engines designed to use only gas. But dual fuel engines have several advantages. For one, most diesel engines can be transformed into dual fuel engines and back. Pon Power has turned a Caterpillar diesel engine into one for the Dutch barge.

Also, a dual fuel engine runs primarily on natural gas, but injection of a small quantity of diesel provides the ignition. Therefore, contrary to in standard gas engines, no spark plug is needed. This saves maintenance in the form of frequent spark plug replacement.

What is more, the engine can switch to gasoil when out of LNG and it is less sensitive to fuel impurities.

LNG versus other fuels
LNG as shipping fuel is interesting for its economics, for one thing. Fuel costs for LNG are five to ten per cent lower than for gasoil. LNG is cheapest when bought directly from an LNG terminal as Belgium port town Zeebrugge has. Rotterdam is scheduled to get its first terminal around the year 2011.

But although technically almost any ship can go on LNG, the energy density of LNG, which is only sixty per cent of that of gasoil, limits practical use. The need for frequent fuel dispatching ties ships to regional infrastructures.

Another, minor disadvantage of gas engines is that their electronic and automation systems tend to be complexer and more sensitive than those of gasoil engines. This, together with the safety risks involved and the necessary safety procedures, requires additional training of operating personnel on LNG ships.

An alternative to LNG is ultra-low sulphur diesel (ULSD). Both alternatives can be used to comply with expected IMO emission reduction regulations. Both also involve extra costs: ULSD is less efficient than standard diesel or gasoil, while LNG requires investments in the form of building or adapting ships and infratructure.

However, the environmental benefits are the main advantage of LNG. By using LNG for shipping fuel emissions can become substantially lower than with ULSD. And if the dual fuel engine can be adapted to liquid bio methane (LBM), which is the plan in the Argonon case, this would further reduce CO2 emissions.

Related articles on MindsinMotion.net

• Merry about a ferry
• LNG shipping: international policies