Fuels of the Future

Reducing a vessel’s speed, to either designated limits or to its optimum, will help in reaching the IMO targets, but this cannot be done alone. Vessel design and alternative fuels will play a vital part.

When considering how to meet these targets, it’s best to look at 2030 and 2050 individually.

The road to 2030

How should we view the year 2030? Should it be “don’t worry, it’s ten years away!” or is it a case of “it’s only ten years away!” We’d subscribe to the latter.

The vessels that will operate in 2030 will consist of many that are either operating today or are being built right now. The question is, will they survive in a new regulatory environment?

Let us revisit the 2030 target: reduce carbon intensity by at least 40% (compared to 2008 levels). Research by DNV-GL in their ‘Maritime Forecast to 2050’ predicts that a significant portion can be achieved through finding operational efficiencies – whether it is speed reduction, optimisation or improving logistics.

Any remainder will need to be met by changing the fuel used by vessels. There are a number of different lower-carbon fuels available to shipping. These include biofuels that are derived from sustainable non-food feedstocks, and liquid natural gas (LNG).

Biofuels

Biofuels can be blended with traditional crude-derived marine fuel oils or used as a ‘drop-in’ fuel, where they act as a direct substitute.

There are numerous biofuels, all derived from various feedstocks through different processes. Two of the more well-known biofuels whose use may become more widespread include heavy vegetable oil (HVO) and biodiesel (FAME, fatty acid methyl ester). Both are sourced from vegetable oil crops but through different processes.

There are several significant barriers to the widespread adoption of biofuels – the nature of which are environmental, economic and technical. For example, fuels must be sourced from sustainable feedstocks if it is to be a ‘green’ option. Also, there is competition for the oil crop feedstocks from the food, cosmetics and pharmaceutical industries. Furthermore, there are long term storage issues with some biofuels, especially if they come into contact with water.

LNG

DNV-GL strongly predict LNG will be the transition fuel of choice. Comprising mostly of methane (CH₄), LNG is already being adopted by an albeit small proportion of the world fleet. It is an attractive option because of its zero-sulphur content (satisfying the IMO 2020 sulphur cap) and its CO₂ emissions are approximately 20% lower than that of distillate fuels (such as MGO) and the new VLSFO products.

However, LNG as a marine fuel is not without its drawbacks. Bunkering, storage and handling takes much more care and presents very different risks to those of traditional marine fuels. Making a vessel LNG-ready requires significant investment – from installing gas (or dual fuel) engines, to additional storage requirements. Also, the global warming potential (GWP) of methane is more than twenty times that of CO₂, which will be an issue if excessive ‘methane-slip’ is experienced in the engines.

The road to 2050

The target is to reduce carbon intensity by at least 70% and this will require significant changes within the next thirty years as to how power and propulsion is generated on board.

The traditional hydrocarbon marine fuels currently in use will be in their death throes. These will be replaced by whichever alternative low-carbon or zero-carbon fuels become the more viable. It is also quite likely that the vessel of 2050 will not be limited to one type of fuel or power source. Multi-fuel may very well be the future.

In their study, DNV-GL predict that by 2050, over 40% of marine fuels will be LNG. There are a number of other alternative fuels in the mix, some of which we will look below:

Methanol

Currently, methanol is produced using natural gas feedstock, and as such it provides only a very modest reduction in CO₂ emissions compared to traditional marine fuels. However, methanol derived from biomass can bring up to a 50% reduction.

Mostly used in the chemical industry, methanol is gaining popularity as an automotive fuel in China.

Methanol is a liquid at ambient pressure and temperature. This makes storage and handling much simpler compared to many of the other alternative fuels.

Hydrogen

Hydrogen fuel, compressed or liquefied, burns with zero carbon emissions. However, hydrogen on its own does not exist naturally and it needs to be produced through energy-intensive processes.

Most of the hydrogen produced today is generated using natural gas or coal energy. For hydrogen to be a truly ‘green’ option, it needs to be generated from renewable power sources. This is currently a costly process.

Ammonia

DNV-GL have predicted that ammonia will be the most popular of the alternative fuels by 2050.

Like hydrogen, most ammonia is currently made using natural gas. For it to be a viable option, it must in the future be manufactured through low-carbon processes. Ammonia can be burnt in dual-fuel internal combustion engine (MAN B&W report only minor modifications to its LPG fuelled engine are required) or as the energy source for fuel cells.

There is precedence on using ammonia on vessels, but this has been limited to its use as a refrigerant. The concerns on its toxicity are well-known and it requires careful handling.

Electric and hybrid systems

The limitations of current technology mean that a fully electric operation – using batteries or fuel cells – is only found on short-sea trades, such as domestic passenger ferries.

A more common variation is the hybrid ship, the concept of which is very similar to that of a ‘plug-in’ hybrid car. The vessel is fitted with electric propulsion motors that are powered by lithium-ion batteries, which in turn are charged when plugged into a shore power supply or from onboard diesel-driven generators.

Bang for your buck

A characteristic common to most (if not all) of the proposed alternative fuels is poor energy density.

The energy density of LNG is about half of that of traditional marine fuels. LNG’s energy density remains superior to that of ammonia, which is in turn greater than hydrogen and lastly batteries.

Low energy density fuels create a storage problem. Space is limited on board a vessel, and the need for larger fuel storage tanks will encroach on valuable cargo carrying capacity.

Crystal Ball

We can’t see into the future, but it is clear that ships will change. With this, the skills of those on board must change too, particularly marine engineers whose training has long-focused on the traditional marine diesel engine.

Further Information

Learn more about LNG with North’s dedicated briefing.

Want to know more about the road to 2030 and 2050? Essential reading from DNV-GL.