HullWiper | A green boost

A green boost

13 Sep 2022

13 Sep22 A green boost

Authored by HullWiper.

As ships navigate from port to port, we know how crucial preparation is to keep them sailing smoothly during the voyages. Typically, with ongoing preventative maintenance, onboarding of new crew, filling up with bunkers, loading cargo and having all of the proper documentation in place, the vessel should be ready to set sail.

Today, more consideration is required. More than 100,000 large ships travel the world's oceans and account for at least 3% of global carbon emissions. Filling up with traditional carbon-based bunker fuels is arguably the biggest contributing factor of air pollution by the shipping industry as the combustion of this fuel releases tons of particulates into the atmosphere.

This is where ship owners and operators could change their planning and preparation – by making the switch to net-carbon zero fuels.

If there’s a will, there’s a wave…of change

The maritime sector, including port and governmental authorities, regulatory bodies, and associations, is responding to its role in the climate crisis.

Europe launched the FuelEU maritime proposal in July 2021, which aims to impose a cap on the greenhouse gas (GHS) emissions of commercial vessels (5 000 gross tons and above) that enter, remain in or leave EU ports. With defined goals of carbon intensity drops of 2% by 2025, 6% by 2030, and 75% by 2050, the objective is to encourage ship owners and operators to embrace, and use, sustainable fuel alternatives.

The IMO’s Energy Efficiency Design Index (EEDI), Phase 3, enforces a 50% carbon-intensity cut on any newbuild of a large containership and by 2050, a 30% reduction on all newbuilds. The most significant technical measure for new ships is the EEDI, which encourages the use of more energy-efficient (less polluting) machinery and engines.

There are a myriad of other initiatives, rules and regulations that have been implemented to transit from conventional heavy fuel oil (HFO) to low-carbon alternatives such as liquified natural gas (LNG), methanol and hydrogen.

Reforming the industry

Let’s examine the benefits and drawbacks of some of these low-carbon substitutes.

Liquefied natural gas

Having just attended Gastech 2022 in Milan, I understand more now that Liquified natural gas (LNG), is a huge improvement over HFO, and is the most common alternative fuel utilized by commercial ships. During manufacturing, LNG nearly becomes sulfur-free, improving air quality by removing sulfur from emissions. LNG could reduce SOx emissions by 99%, NOx emissions by 80%, and CO2 emissions by as much as 20% while producing comparatively little particulate matter. The fuel is liquefied by cooling the gas combination to cryogenic temperatures (-162 °C), taking up roughly one-six tenth of the gas's volume- this allows it to be stored in non-pressurized containers. A significant drawback is that LNG mostly consists of methane, which has an estimated 86 times greater global warming potential.


As the only combustion by-product of hydrogen is water, it is frequently proclaimed as a clean fuel. But how the fuel is produced has a big impact on how eco-friendly it is. Three categories can be used to label hydrogen production: grey when hydrogen is produced by reforming natural gas or other fossil fuels, which accounts for about 95% of all hydrogen produced globally; blue when carbon emissions are captured, stored, or used; and green when hydrogen is produced using renewable feedstocks and renewable energy sources. The best option for significantly reducing carbon emissions is liquid hydrogen, but the fuel must be green to result in low emissions.


Methanol is a liquid that can be kept, transported, and consumed at room temperature, making it a more viable alternative compared to other alternative fuels. It is produced via the conversion of synthesis gas, a mixture of carbon monoxide and hydrogen produced by reforming a natural gas or coal classification. There is no need for cryogenic or pressurized tanks so the Capital Expenditure (CAPEX) for a vessel is rather minimal. But methanol may not be a net-zero option due to methane emissions during production and combustion. The primary difficulties for this fuel source are producing green methanol, as well as in balancing eventual demand with supply and cost.


A class of alternative fuels known as "biofuels", using the conversion of raw biomass (biological organisms) or biomass wastes into liquid or gaseous fuels, is considered to be carbon-neutral because it emits very little CO2, has very low sulphur levels and has the potential to cut greenhouse gas emissions by 40 - 93%. However, producing the required volume to service major shipping routes remains a challenge.

Renewable energy

Options for lowering emissions along some shipping routes include wind and solar energy. According to preliminary studies, solar energy can cut CO2 emissions by up to 12%, and onboard wind-solar hybrid systems can save up to 40% on fuel. A major drawback is that only a small number of shipping routes can be full navigated using renewable energy.

Health check

A thorough review of hydrogen, ammonia converts, methanol and other fuel cells was conducted by Turnock and maritime engineering colleagues Charles J. McKinlay and A. Hudson (University of Southampton, UK). Although these fuel sources can be burned in combustion engines, they found that using them in fuel cells would extract the greatest energy potential and provide the prospect of producing power without any emissions. However, the infrastructure isn’t in place yet, and it will be some time before enough is readily available to bunker a large container ship. Fuel cell use also requires vessels with electrically powered propulsion systems, which are less common than ships with internal combustion engines.

It's not too late for change. Change is good, and change will sustain the future of our planet “A” (we don’t yet have planet “B”).