Pathways to decarbonisation

Pathways to decarbonisation

As the shipping industry strives to decarbonise to meet the International Maritime Organization’s (IMO’s) target of achieving at least a 50 per cent reduction emissions by 2050 compared with 2008 levels, new technologies and fuels are being developed and tested. While many have shown success for short sea shipping, they often have practical limitations for application to commercial ships.

A new research report published by classification society ABS suggests that the fuels or technologies that have the strongest potential to reduce the carbon footprint of vessels may not be practically viable at this time. Models developed as part of the research indicate that shipping could miss the IMO’s 2050 GHG emissions target annually, with a gap between the industry’s present course and its ambition evident. Any potential technologies and fuels will need to be assessed on their technological readiness, their potential for large scale commercialisation, and their ability to reduce the carbon footprints of vessels in the short, medium and long term.

Future fuels and technologies for decarbonisation

The report has identified three main fuel pathways to meet IMO 2050 GHG target that could be both practical and viable. These are:

  • Light gas fuels – including liquefied natural gas (LNG), bio-LNG, and synthetic natural gas (SNG) or renewable natural gas (RNG).
  • Heavy gas and alcohol fuels – including liquefied petroleum gas (LPG), methanol, ethanol and ammonia.
  • Bio/synthetic fuels – including fuels from biomass such as plants, waste oils and agricultural waste.

Producing electro-fuels from renewable energy, which would reduce the energy required for their production and cut carbon emissions significantly, could also be applied to any of these fuel pathways to produce bio-LNG, bio-methanol or renewable diesel.

The type of fuel or technologies used onboard a vessel will depend on its operating profile in terms of trading route and cargo.

Carbon capture

Carbon Capture and Sequestration (CCS) has been identified by ABS as one method to help cut carbon emissions from international shipping. CCS involves trapping and removing CO2 at the source of its emission and storing it for future use. With ships, CO2 can be removed from vessel exhaust gas or the atmosphere.

CCS technologies have gained interest over the last several years with continuous research taking place to identify the costs and viability of CCS for decarbonisation.

Mitsubishi Heavy Industries (MHI) recently installed a marine carbon capture and storage unit on a very large crude carrier (VLCC) to produce of methane or methanol by combining hydrogen from water electrolysis with the captured CO2. The result was a reduction in CO2 of 86 per cent. However, as ABS reports, the capital cost required for the CCS system was about $30M, and the cost for the methane or methanol production system used was an additional $15M.

Hybrid electric power

Hybrid-electric propulsion systems can significantly reduce emissions from ships. They are currently largely deployed on offshore support vessels and harbour tugs. Hybrid-electric power systems combine engines, batteries or supercapacitors, fuel cells, and electric motors to

form the power generation and propulsion system of the vessel.

Batteries are used for hybrid-electric propulsion, but they currently have a relatively short lifetime. Most marine batteries are designed to last between seven and ten years, which ABS says needs to be extended to over 15 years in order to match the lifespan of a vessel, which can be a challenge for manufacturers.

Guidelines and rules are increasingly being developed by classification societies such as ABS to help the industry adopt hybrid systems.

Technology is also developing and more complex electrical systems are being tested. While more complex designs are more difficult and impractical to assess using traditional methods, ABS says that new modelling and simulation tools and techniques are helping here. The more these simulation techniques are used to assess the electrical aspects of the design, the more the designer is able to consider other variables, including non-technical considerations such as capex, opex and specific regulatory requirements.

Fuel cells

Fuel cells are being increasingly trialled on marine applications. According to ABS, the high energy density of hydrogen used in fuel cells and the potential for fast refuelling, both of which are major challenges for batteries, make fuel cells particularly interesting for marine vessels.

Current fuel-cell technology can be used either with pure hydrogen or with other fuels that can be used to extract hydrogen.

There are various joint industry projects in place that are developing and testing fuel cell applications. ABS is involved in developing a prototype hydrogen fuel-cell unit to power onboard refrigerated containers, while Oslo-listed Havyard Group is working with other Norwegian companies to design, certify and deliver a large-scale hydrogen power solution that can be retrofitted onto ro/pax vessels. NCE Maritime CleanTech is looking at fitting offshore support vessel Viking Energy with a 2-MW fuel cell using ammonia. The project is scheduled for completion in 2023 and will test the feasibility of using sustainably sourced, ammonia in a SOFC system on a commercial ship. Japan’s Tokyo Kisen and e5 Lab are also working with several groups to develop the design and regulatory baseline for a hydrogen fuel-cell powered tugboat.

DC systems

Direct current (DC) power distribution systems is another option presented in ABS’ report that could improve the efficiency of marine operations. However, the application is relatively new to the marine industry and it is only in the past few years that full DC networks have been used in small vessels. According to ABS, new systems require crew training, awareness, and familiarity, and the supporting components do not have a long history of operations in marine environments.

Shipping’s decarbonisation and global trade

According to ABS and its collaborative partner Maritime Strategies International (MSI), many of the noted fuels and technologies will contribute towards shipping’s decarbonisation. However, by examining a range of ship types that comprise the majority of the deep-sea fleet (dry bulk carriers, oil and chemical tankers, containerships, LNG carriers, and LPG carriers) ABS and MSI identified key changes in the economy in the volume and pattern of trade in the full range of commodities transported by sea over the next 30 years. ABS reports that these changes will affect the fleet evolution across the shipping spectrum, and reduce the aggregate fleet size in some sectors by 2050.

Low-carbon fuels such as LNG, LPG, and methanol will assume a significant role in the near term, but the adoption of zero-carbon fuels must begin in earnest before the end of the current decade, says ABS.

The report states that it has yet to become clear what the carbon footprint of biofuels and synthetic fuels will be, and how this could be measured in a standardised manner.

ABS reports that the projected marine fuel use could help the shipping industry meet the target to reduce by 70 per cent CO2 emissions per transport work (gCO2 /dwt/nm) by 2050. However, the 50 per cent reduction in CO2 emissions (ton) over the same timeframe, and to meet the IMO’s 2050 target, will require additional measures including the reduced share of oil-based fuels by 2050 below the 40 per cent level projected in this study through greater adoption of low and zero-carbon fuels; and the broader decarbonisation of the global economy.

Just-in-Time and ship design

Just-in-Time (JiT) ship routing and the design of future ships will also play a role in helping the industry to decarbonise, reports ABS. Recent reports by Marine Traffic that indicate that ships spend roughly 50 per cent of their time in berth, anchoring or manoeuvring, which accounts for more than 15 per cent of their annual fuel consumption.

Adoption of JIT operations would reduce the time spent waiting for berths or trade, maximise the utilisation of ports and reduce the fuel costs associated with port stays, as well as reducing GHG emissions.

The design of ships in the future will also play a role in eliminating emissions from ocean-going vessels. ABS has partnered with Herbert Engineering Corp. (HEC) to develop a series of tanker, bulk carrier, and container ship design concepts to provide visual representations and specifications of practical options for meeting the 2050 goal. Page 93 of the report provides further detail on ship design, energy efficiency and emissions.

“Maritime’s decarbonisation challenge can be regarded as a complex riddle with three elements: vessel energy efficient technologies, operational optimisation 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. In short, there is a gap between the industry’s present course, and its stated ambition.”

Download the report here.