The Low-carbon Ship

Easing ship owners into the fuels and demands of tomorrow

Taking on the challenge of ship decarbonisation is a two-tier process-delivering efficiencies and sustainability benefits for today’s markets, while simultaneously preparing the industry for future developments. Given the lengthy lifespans of most vessels, manufacturers of ships and ship components are attempting to divine the future to see which fuels will come out on top at the end of the transition to green energy. Simon Qu from Kongsberg Maritime argues that the shipping industry has options to spread their bets on the fuels of tomorrow.

Dual-fuel engines

A core component of ship decarbonisation is the widespread adoption of dual-fuel engines and liquified natural gas (LNG): although a fossil fuel, LNG’s cleaner burning offers a quick win in comparison with magnesium oxide (MGO). With LNG, carbon dioxide (CO2) emissions are reduced by 24 per cent, nitrogen oxide (NOx) emissions by 87 per cent and sulphur oxide (SOx) emissions by a whopping 99 per cent. In addition, particulate matter is negligible, and analysis demonstrates that the benefits are not only environmental – operators can expect expenses savings too when market forces allow.

Extra power

Adoption of power take-off (PTO) technology is another key strategy. Propulsion engines often run significantly below maximum load, so by installing a PTO this spare capacity can be converted into extra power for non-propulsion needs aboard ship at little extra cost. Any spare power a ship can get from PTO can assist in reducing the number of auxiliary generator sets required.

Future fuels

One of the foremost questions in vessel owners’ minds when specifying a newbuild or refit is how they will manage the introduction of new fuels – the so-called ‘fuel transition’. Several alternatives are waiting in the wings – hydrotreated vegetable oil (HVO), synthetic methane, methanol, liquefied hydrogen (LH2), ammonia and liquid biogas (LBG),  to name but a few. Some of these will grow and dominate the fuel mix in the future, but others will likely never gain enough momentum, nor build the required worldwide infrastructure, and drop from the scene. For operators investing in future ships, it is difficult to know which horse to back.

With no conclusive answers, the logical solution is to hedge bets by equipping vessels with engines and systems which will allow as many of these fuels to be used as possible, with zero or minimal modifications.

For example, as synthetic methane and LBG are methane fuels, just like LNG, a LNG-powered vessel is ready for at least two new low-carbon or carbon-neutral fuels with no modification at all. A dual-fuel engine that can burn MGO, meanwhile, can also switch to renewable HVO with little or no upgrade required. If an LNG system is designed with fuel transitioning in mind, conversion to operation on ammonia can also be relatively simple too.


Many stakeholders are also researching the use of hydrogen, in both liquid and gas phases. Inevitably, hydrogen’s flammability and explosive nature make safety a key concern, so extensive work is required before it can be approved for use. However, the cost of storage of the high volumes of hydrogen required—for example, aboard a container vessel—might rule out this technology for longer routes.


Current battery technologies mean that fully-electrified vessels are only suitable for shorter routes between locations with charging infrastructure. As an example of efforts to expand this range,, Norway is preparing fixed facilities on the Oslofjord that will be equipped with the necessary charging infrastructure required by cargo carriers. Power will come from Norway’s national grid, which currently derives 98 per cent of its energy from renewable sources, mostly hydro power.

Vessels making longer voyages between multiple ports have more problems to solve. Full battery operation for ocean passages is currently impracticable, owing to the size and cost of the required energy storage, but there is the potential to use hybrid systems with stored energy to allow battery operation for parts of the passage, such as entering and leaving port.

Plus, not everywhere in the world currently derives its electricity as cleanly as Norway. Even if charging infrastructure improves, the provenance of the power must also be reliable. A great deal depends on how dirty the electricity is on land. From a CO2 emissions perspective, if vessels charge from shore, they must be assured that the shore connection has clean energy going to it. For such integrated solutions for instilling lean and green operational efficiencies to succeed in the long-term, they will need input and support not only from the shipping industry, but also from governments, power companies and society.

Kongsberg Maritime is a global marine technology company providing innovative and reliable ‘Full Picture’ technology solutions for all marine industry sectors including merchant, offshore, cruise, subsea and naval. Headquartered in Kongsberg, Norway, Kongsberg Maritime has manufacturing, sales and service facilities in 34 countries. Kongsberg Maritime is part of Kongsberg Gruppen (KONGSBERG), an international, knowledge-based group that celebrated 200 years in business during 2014. KONGSBERG supplies high-technology systems and solutions to customers in the oil and gas industry, the merchant marine, and the defence and aerospace industries.