The shipping industry faces significant challenges in establishing how to calculate lifecycle greenhouse gas (GHG) emissions from alternative marine fuels, vessel classification society DNV said in its Maritime Forecast to 2050 report.
The International Maritime Organisation (IMO) in July changed its marine fuel emissions directive from combustion to lifecycle, or well-to-wake emissions. Before that decision, ship owners were looking to mitigate emissions from fuel combustion only. The regulatory focus on lifecycle GHG emissions and sustainable production implies that marine fuels will be subject to production standards certification to verify their origin, DNV said.
Challenges in establishing lifecycle calculation methods include how to account for direct and indirect land use emission from biofuels, as well as accounting for the greenhouse gas intensity of electricity used for fuel production, according to the report. Challenges also include accounting for onboard carbon capture and storage (CCS) and the use of recycled carbon in the fuel, as well as how to certify well-to-tank emissions.
Certification schemes already exist for biofuels, such as those from International Sustainability and Carbon Vertification (ISCC) and the Roundtable on Sustainable Biomaterials (RSB). Several initiatives are underway in different parts of the world for developing schemes for other types of fuels such as hydrogen and hydrogen-derived fuels to certify their origin, such as Australia's guarantee of origin scheme, the China Hydrogen Alliance and the EU's CertifHy.
The DNV report also examines the feasibility of onboard CCS. It models a 15,000 twenty-foot-equivalent unit (TEU) container ship with 4,000m³ of CO2 storage on board. The vessel offloads CO2 twice per Asia-Europe trip and annually captures of 70pc of CO2. If the increase in energy used to capture the CO2 can be kept below 15pc and if the cost of offloading, transporting and sequestering the CO2 is below $40/t, onboard CCS can be a competitive option for decarbonization.
Of the 2,002 ships in the global fleet, 93.5pc as measure by gross tonnage run on conventional marine fuel, 5.96pc operate on LNG and the remaining 0.54pc operate on batteries, LPG and methanol.
The newbuild vessel order book is comprised of 1,376 vessels, the report said. Of these, 48.7pc by gross tonnage will run on conventional marine fuels, 40.3pc on LNG, 8.01pc on methanol and the remaining 2.99pc on LPG and batteries.
Methanol has previously been a choice exclusively for tankers in the methanol trade, with 23 ships in operations and 14 tankers on order.
This year, the container ship segment is dominating demand for methanol-fueled ships, with 142 on order, DNV said. Currently, 72 LPG carriers using LPG as fuel are sailing, while 93 LPG carriers and 4 ethane carriers have been ordered with LPG-burning capacity.
While several demonstration projects for ammonia-fueled ships are ongoing, there are no ammonia-fueled ships in the official order book. Wind-assisted propulsion systems have now been installed on 28 larger vessels, and air lubrication systems are installed on or ordered for more than 250 vessels.
Vessels can burn biofuels without the need to retrofit. Currently only 0.1pc of fuels used by merchant shipping are biofuels. The global production capacity of sustainable biofuels is around 11mn t/year and DNV's database indicates that this could grow to 23mn t/year by 2026. If shipping were to fully decarbonise primarily using biofuels, about 250mn t/year would be needed.
