Is liquefied natural gas (LNG) the future of marine fuel – or just a future marine fuel? The ideal fuel is affordable, clean and readily available, but which one fits this bill best?
The search for alternative fuels is partially driven by NOx and SOx emissions limits. As LNG is low in sulphur and gas engines have lower NOx emissions than oil engines, it could be a viable option.
However, the number of LNG-fuelled ships being ordered is a small proportion of the total and, in terms of the existing fleet, statistically insignificant. For LNG to supplant oil, it needs a fuel supply infrastructure to be in place, requiring significant investment, says John Bradshaw, Lloyd’s Register (LR) Marine’s Lead Project Engineer for Machinery.
Cleaning Emissions
But there are also other options, such as cleaning emissions. Exhaust gas cleaning is now a mature industrial technology and allows ships equipped with these systems to combust high sulphur residual oil in emission control areas.
Other options include:
- Biofuel use is increasing; fatty acid methyl ester (FAME) biodiesel is widely available, but increasing societal resistance against FAME will make next generation algae derived bio-oils much more attractive.
- Methanol is generally derived from natural gas feedstocks, but with renewable feedstock being available it has great potential as a clean fuel. Although toxic and flammable, fuel handling and risk management is simpler than for LNG, since it is not a cryogenic liquid.
- Hydrogen has traditionally been energy intensive to produce in large quantities and risk management is challenging, however it is potentially both clean and abundant. If efforts to reduce the cost of generating hydrogen reach fruition, then it could potentially become the holy grail of energy; cheap, clean and abundant fuel.
- Nuclear energy is mature, clean and reliable, but acceptance of nuclear energy faces significant political, regulatory and societal challenges.
- Renewable energy, such as wind and solar, will augment fuels, such as gas or oil, but are unlikely to replace them.
Future Outlook
There is no ‘one size fits all’ best solution, says Bradshaw. Market fragmentation with operators selecting solutions fitting their own needs is likely, perhaps resulting in multiple fuel policies within an operator’s fleet.
LR expects to see continued strong growth in the LNG fuel market, with oil retaining a large market share. Alternatives, such as methanol, biodiesel and hydrocarbon gases including LPG, will gain traction, while more radical alternatives, such as hydrogen and nuclear, should not be discounted.
Picture: LNG tanker (Peter Welleman, Wikipedia)
