Shipping’s carbon-neutral dream drifts further away

Total emissions by large ships are still increasing, despite some efficiency gains via alternative fuels.

trade deficit
Big ocean-going ships have found it more difficult than smaller vessels to switch to carbon-neutral fuels, which are expensive and not as readily available [File: Ted S. Warren/AP]

Big ocean-going ships are not moving fast enough towards energy transition, contributing to rising emissions of carbon dioxide for the entire fleet and undermining efforts to make the industry carbon-neutral by the end of the century.

While smaller boats are making first steps to apply batteries and hydrogen, deep-sea trade, which involves a third of global fleet and accounts for more than 80% of its CO2 emissions, is proving harder to decarbonize, according to a report published by DNV GL, which classifies and certifies ships for safety. With just 0.3% of operational global fleet using alternative fuels and 6.1% in the order book, total emissions are still increasing despite efficiency gains.

Marine trade emissions

“Uptake of alternative fuels and technologies is picking up pace, but is still at a level where the vast majority of tonnage ordered uses traditional fuels,” the report said. The increase in low- and zero-emissions fuels is “dominated by the short-sea segment and non-cargo ships, and has little impact on total maritime emissions.”

Industries from electricity generation to ground transportation to construction are seeking greener alternatives in a worldwide push to cut carbon emissions and combat climate change. The shipping industry remains among the dirtiest, prompting the International Maritime Organization last year to introduce a strategy seeking to halve the sector’s emissions by 2050 from 2008 levels and make the industry carbon-neutral by 2100. That’s on top of a clampdown next year on sulfur emissions.

But as seaborne trade increases by 39 percent by 2050, driven by all segments except oil and oil products trade, emissions will only reduce by 27% under current policies and unless carbon-neutral fuels become competitive with fossil fuels, DNV GL said.

Smaller vessels that cover shorter distances and trades of up to one hour can use renewable electricity and energy from batteries, fuel cells and waste heat. But huge ocean-going ships are trickier to switch as most of their energy consumption relates to propulsion at steady speed over long distances, and battery applications would not provide enough energy for such long voyages. In addition, they need fuel that’s safe, globally available and doesn’t take up a lot of space and storage capacity.

The main options for such big trade vessels today are liquefied natural gas, which is cleaner but not carbon-neutral, or biofuels, which are not yet widely available and expensive, the report said.

Moving the deep-sea fleet over to zero-carbon fuels will require developing alternatives such as ammonia.

Ammonia is the most promising carbon-neutral option for new ships, thanks to the lower cost of the converter, storage and the fuel compared with hydrogen and liquefied bio gas, according to the report. However, no current marine engine is capable of burning it, and development is expected within the next few years, the report said.

“The share of carbon-neutral fuels in world fleet energy needs to be 30%-40% in 2050, in addition to improving energy efficiency, to achieve IMO GHG ambitions,” the report said. “If the IMO targets are to be met, it is vital that uptake of low- and zero-emission technologies should begin on large ocean-going ships in the near future.”

Source: Bloomberg