There are three potential fuel pathways toward developing zero-emission vessels and decarbonizing the future of shipping, according to ABS.
The US-based classification society just released the 2020 Setting the Course to Low-Carbon Shipping — Pathways to Sustainable Shipping outlook, which maps out the path toward decarbonization goals of the global fleet.
The three fuel pathways are: (i) light gas, (ii) heavy gas-alcohol, and (iii) biofuel or synthetic fuels.
ABS says that owners and operators should choose their pathway based on two foundational criteria: the type of vessel and its operating profile in terms of trading route and cargo.
The study was carried out in cooperation with Maritime Strategies International (MSI) to create a global scenario for the future CO2 emissions from shipping, and the outlook’s approach was supported by Maersk.
“Maritime’s decarbonization challenge can be regarded as a complex riddle with three elements: vessel energy-efficient technologies, operational optimization and low and zero-carbon or carbon-neutral fuels. All elements have a role to play, but we have identified that the rate of shipping’s transition to lower carbon fuels will have the single biggest impact on its global carbon footprint; more than any predictable shifts in commodity demand, enhancements to operating practices, vessel routings, or ship designs.,” said Christopher J. Wiernicki, ABS Chairman, President and Chief Executive Officer.
“The models in our research suggest our industry will meet the targets for the reduction in carbon intensity by 2050, but it might miss the target for the total GHG emitted annually. ”
The Light Gas PathwayThis category includes fuels comprised of small molecules with low-carbon/hydrogen (C/H) ratio, which helps to reduce carbon emissions.
Such fuels include LNG, bio-LNG, and synthetic natural gas (SNG) or renewable natural gas (RNG), which can be produced from biomass and/or by using renewable energy. The production of synthetic or renewable fuels from biomass is currently limited in scale and will have to be increased before they can be considered as viable commercial solutions.
LNG is a relatively mature low-carbon fuel, comprised primarily of methane. Its C/H ratio offers a reduction in carbon dioxide (CO2 ) emissions of up to 21 percent compared to baseline heavy fuel oils, the outlook reads.
The value does not include carbon release from methane slip, which may be an issue in two-stroke or four-stroke engines that operate on LNG in the Otto cycle.
Minimizing methane slip has been described as critical to the commercial adoption of these renewable fuels.
The industry is currently developing in-cylinder emissions control strategies, which could be combined with after-treatment systems. By minimizing methane slip, fuels such as bio-LNG and SNG/RNG can offer carbon-neutral propulsion.
The two-stroke and four-stroke engine manufacturers already offer solutions for minimizing methane slip from combustion, using high-pressure gas injection in the cylinder.
These can be combined with methane oxidation catalysts and other after-treatment systems used to treat the exhaust gas to further reduce the methane emissions and minimize the carbon output of using LNG.
As a low-carbon fuel, LNG can be combined with new technologies and/or operational measures to meet the 2030 emissions-reduction goals, and it can contribute to further reductions in the future, if blended with bioLNG or SNG/RNG.
If the latter can be commercialized and made available at a large scale in the medium term, the carbon footprint from using LNG would be reduced in proportion to the amount of renewable fuel used in the blend. Given the carbon-neutral promise of bio-LNG and SNG/RNG, significant efforts are currently being made to explore these solutions for commercial use, ABS said in the outlook.
At the end of the light gas spectrum, hydrogen may be a solution for future zero-carbon marine vessels, because it offers the highest energy content per mass among all candidate fuels, high diffusivity, and high flame speed.....MUCH MORE
However, it also requires cryogenic storage and dedicated fuel supply systems for containment. Hydrogen as a fuel has been demonstrated in internal combustion engines, gas turbines, and fuel cells, all of which will play a role in marine power generation and propulsion systems.
Nevertheless, as ABS explains significant technical advances are needed before hydrogen can be considered a viable, large scale, commercial fuel option....
As their graphic for the light gas segment of the article the editor used a picture of CMA CGM's flagship, the LNG-powered monstre de la mer, 23,000 TEU Jacques Saade.
(I'm not sure when the Saade will take the flag from the current flagship, the 20,600 TEU Antoine de Saint-Exupéry. Sometime this year)
