1. New maritime fuels

Shipping is considered as one of those “hard to abate” sectors, where achieving net-zero emissions by mid-century is expected to be very difficult¹¹. Amongst the major barriers to rapid change are the lack of commercially available mitigation technologies, plus large upfront costs combined with slow capital turnover rates and market competitiveness. Other analysis argued that the perfect “zero emission” fuel does not yet exist, as the alternatives to fossil fuels come with trade-offs between technological innovation, operational measures and rethinking supply chains.

Another facet was highlighted in a study¹² (from May 2022) stating that the world’s renewable energy generation would need to increase up to 100% just to supply enough (net) zero carbon fuel to power the shipping industry.

The need for other actors to also play their part in decarbonising the shipping sector is also identified. In particular calling on the technical readiness of the shipping industry to now be matched by fuel supply, regulatory clarity and the thorny issue of who pays for the cost differential in the zero-carbon energy transition.

The maritime sector, as a whole, has come together to determine how to address the challenges for achieving zero- or low-carbon fuels. For example, the Getting to Zero Coalition, is an alliance of more than 200 organisations (including 160 companies) within the maritime, energy, infrastructure and finance sectors, supported by key governments and Intergovernmental organisations. It was setup as a partnership between the Global Maritime Forum and the World Economic Forum. The coalition is committed to getting commercially viable deep sea zero emission vessels powered by zero emission fuels into operation by 2030 towards full decarbonisation by 2050.

The “Together in Safety” group produced a risk assessment of the main alternative fuels being considered, specifically liquified natural gas (LNG), Methanol, Ammonia and Hydrogen. It is widely acknowledged that such fuels of the future will bring additional risks to seafarers. Within the constraints of the report’s scope, they concluded that Methanol would require the least effort with regards to additional safety measures, followed by LNG, Hydrogen and Ammonia being the most demanding, but with all requiring inherently safer designs for implementation. Indeed for Ammonia, there is a concern over its potential (negative) impact on the marine environment in case of spills, as well as on the global Nitrogen cycle. There are now also guidelines for ships using alternative fuels.

The Mærsk Mc-Kinney Møller Center for Zero Carbon Shipping¹³ has looked into specific emissions that need to be addressed to increase alternative fuel pathway maturity. They looked at current or potential emission levels, set reduction targets, and identified and mapped applicable technologies and solutions. From this, emission reduction potential is then determined and recommendations given to develop further the selected fuel pathways, including areas or concepts for further research and development.

To ensure global coverage, the Global Centre for Maritime Decarbonisation (GCMD) is leading a consortium of 18 industry partners to launch a drop-in biofuels pilot project with a combined contribution of US $18 million to establish a framework for ensuring the supply chain integrity of current and future green marine fuels.

Looking to the future, the company DNV produced its Energy Transition Outlook 2022¹⁴, providing a detailed forecast of the demand and supply of energy towards 2050, as well as a pathway to reach net zero emissions. The report provides outlooks on drivers and regulations for decarbonisation; on ship technologies and fuels; on the readiness of onboard fuel technologies; on alternative fuel production and infrastructure; and on pathways for decarbonisation.

1.2.1 Biofuels

There are a number of studies which have indicated that biodiesel fuel is suitable for use as an alternative fuel for marine engine applications¹⁵. Many reports have revealed that alternative fuels derived from vegetable oil and animal fats were found to be environmentally friendly, renewable, non-toxic, biodegradable, sulphur free and aromatic. The European Maritime Safety Agency (EMSA) also produced (in October 2022), an update on the potential of biofuels for shipping. A biofuel from kelp harvesting and fish processing waste has also been developed.

Commercially, the Finnish oil refiner, Neste, has developed a biofuel that is said to cut greenhouse gas (GHG) emissions by up to 80%, without compromising product quality and performance.

The company SeaH4¹⁶ has developed biofuels generated from farmed algae which is indigenous to the region it is farmed from, thereby avoiding as well any introduction of invasive species. This is presented as a carbon neutral alternative to fossil fuels enabling full and continued use of the existing fossil fuel infrastructure, whilst being protected from GHG emissions levies, taxes and penalties. They state that their fuels require no changes to engines nor the existing distribution network. Using well-established technologies, they produce some 15 000 t of bioLNG per year and their analysis gives a saving 2.8 t CO2-equivalent per ton of fuel consumed. There is a potential also to produce Compressed Natural Gas (CNG) or biodiesel, specifically for fishing vessels.

The use of marine fuels blended with these biodiesels can be considered as the proper way to reduce air pollution at sea and simultaneously meet IMO regulations. However, there are some obstacles that arise, such as fuel stability, higher production and feedstock costs, material compatibility, cold flow properties and lack of marine-grade standards. A study¹⁷ (from Nov. 2021) also highlighted that there is no clear green alternative fuel to fossil marine fuels at this stage. The technological readiness of fuel technologies was assessed as moderate to high, while the commercial readiness was in general low. Innovation, together with other market supporting measures, was needed to accelerate the readiness of technologies and support the commercialization of these technologies.

A fishing vessel in New Zealand, Endeavour, was constructed to run on biofuel, supplied wharf-side. The trawler, 17.2 m long with a 6m beam and a displacement of 125 tonnes, has the capacity to carry up to 8 520 litres of fuel. It is claimed that, for every tonne of used cooking oil used to produce the biofuel, there is a corresponding two tonne reduction in CO₂ emissions. The biofuel is also able to reduce particulate emissions by up to 50% compared to conventional diesels.

1.2.2 Developments by industry (startups, shipbuilders and marine engine producers

In Italy, the company Bi.Nav Consulting via its Horus Project is developing battery-based vessels. The project, supported also by the WWF and the Associazione Mediterranea Acquacoltori, aims to decarbonise aquaculture service vessels, notably for molluscs. Their vessels have a full electric system using batteries which can be charged when in dock, but also on board in case of emergency.

Also in Italy, the start-up company Sea Opportunities via its ETICA IP platform, which is an Integrative Platform for Remotely Operated Vessels (ROV) and Unmanned Service Vehicles (USV), is completely powered by renewable energy with zero emissions. Its propulsion and power supply system is 100% electric, rechargeable directly from photovoltaic panels. They provide a large range of surface and subsea services for the Blue Economy industry, including aquaculture.

The Norwegian company, ZeroKyst, aims to set into motion a rapid technology shift for all vessel types in the fisheries and aquaculture industry. They plan to develop and demonstrate a new zero-emission powertrain (Siemens Blue Drive and HybridZ), a new zero-emission vessel, 10 retrofitted vessels, services for retrofitting and maintaining zero-emission vessels, and a complete solution for a flexible supply of electricity and green hydrogen as maritime fuel.

Another Norwegian company, Corvus Energy¹⁸, is also active for the fishing and aquaculture sectors, specifically in developing energy storage systems (ESS) that reduces fuel consumption, costs and emissions, whilst enabling silent operations and contributing to increased safety. With such a system, a vessel may run only on battery-power during fishing and other similar low power operations. For higher power operations, the vessel gets the option to run diesel-electrical, thereby charging the ESS utilising generators and making it ready for all-electric usage later. The savings on fuel due to energy optimisation by an ESS on a fishing vessel is said to be typically 25%, whilst simultaneously reducing emissions by 25-40%.

Elsewhere, hybrid diesel-hydrogen engines are now commercially available¹⁹, including for the shipping sector²⁰, and it is possible also to retrofit an existing diesel engine²¹, although seemingly not yet for those on fishing vessels.

Other major ship engine companies, like MAN and Wärtsilä are also developing propulsion systems that can run on alternative fuels or be adapted to run on alternative fuels. For example, MAN offers to retrofit new engines in preparation for future, climate-neutral operation and dual-fuel operation²².

1.2.3 New developments

Fuel Oil Emulsion (FOE) technology by the company Blended Fuel Solutions burns more completely than unmodified fuel and so uses less fuel, emissions are lower, and the engines run cooler and so should require less maintenance. This would reduce the use of fuel and the level of emissions as well as give a significant financial saving.

The company Expleo has developed a closed-loop fuel solution for shipping which they claim delivers a 92% reduction in greenhouse gas emissions and Operating Expenses savings of £1.4 million (approx. €1.6 m) a year, per vessel²³. The solution uses Solid Oxide Fuel Cell (SOFC) technology partnered with a novel carbon capture and storage system, enabling a vessel to use its captured CO2 and green hydrogen to synthesise e-methanol. The green hydrogen in the solution could be produced at offshore wind farms, from surplus electrical energy or supplied in-port – ensuring the closed-loop remains as sustainable as possible.

Another example concerns using a solid form of hydrogen released from a salt called sodium borohydride (NaBH4), which is said to be far safer and easier to store than compressed or liquid hydrogen. A prototype vessel, Neo Orbis, is under construction in the Netherlands to test this approach.

Also under serious consideration across the world is the development of nuclear-powered vessels, specifically using Small Modular Nuclear Reactors²⁴. In Norway, as part of their Research Council’s Maritime 21 strategy, a project to design small modular nuclear reactors for the propulsion of large vessels was selected, with NOK 10 million of funding. In a complementary manner, floating nuclear power plants are also under consideration. For example, the vessel Ulstein Thor, using a Thorium Molten Salt Reactor, operates as a mobile power/charging station for battery-driven cruise ships. Samsung Heavy Industries has developed a conceptual design for a floating nuclear power plant barge, based on compact molten salt reactor (CMSR) technology.