Into perspective

by Paul Delouche, Strategy Director, Bureau Veritas Marine & Offshore Decarbonising shipping in isolation does not make sense. If we are to make a genuine difference for the climate’s sake, then we need a cross-sector approach not only to develop and scale up new fuels – but also to properly evaluate the environmental impact of alternative fuel options, from their production to their use on board. If we are to achieve true decarbonisation in shipping, we need to assess whether the different fuel options gradually being adopted will actually reduce the amount of greenhouse gas (GHG) emissions released in the atmosphere. And we can only do that by taking a well-to-wake (WtW) approach – by looking upstream and across sectors to understand the production and logistics changes occurring as society as a whole develops new sources of power and new fuels.

The shipping sector’s current decarbonisation regulations are based on a tank-to-wake (TtW) approach. To this day, the International Maritime Organization’s Data Collection System and Carbon Intensity Indicator regulations do not include emissions before onboard combustion. However, the EU has notably proposed a WtW approach when drawing up its FuelEU Maritime regulations, which are under discussion.

This is an important development: TtW and WtW calculations can vary significantly. Carbon-free fuels can generate higher WtW emissions than the fossil fuels that they are intended to replace, depending on how they are produced.

Our recent white paper, Alternative

Fuels Outlook for Shipping – an Overview of Alternative Fuels from a Well-to-Wake

Perspective, reports that typical WtW emissions of ammonia and liquid hydrogen, as currently produced from natural gas, are typically higher than those of liquefied natural gas (LNG), marine gas oil and very low sulphur fuel oil, based on 100-year global warming potential (GWP). Therefore, to decarbonise shipping, ammonia and hydrogen – and indeed all new fuels – will need to be manufactured from low-carbon supply chains.

This positions electro-fuels (e-fuels), produced from renewable energy, as one of the most promising options to achieve true decarbonisation in WtW terms, alongside second-generation biofuels produced sustainably from renewable feedstocks.

Upstream variation

All fossil-based fuels emit more GHG emissions throughout their entire value chain than second-generation biofuels and e-fuels. Methane slip is a crucial consideration when using LNG as fuel, as it increases a ship’s GHG emissions, especially in low-pressure engines (although still delivering a GHG emission reduction vs traditional marine fuels).

Methane leaks are another critical consideration. Upstream methane emissions occur during extraction, processing, transportation, and onboard handling before combustion. These leaks depend highly on the production pathway and location. For example, shale gas production sites are likely to have more leaks than conventional natural gas wells.

The WtW emissions of e-fuels will depend on the type of renewable energy used to produce them. For example, hydropower generally has a lower GHG emission factor than solar power: green hydrogen produced with the former will therefore be greener than one made with the latter. However, WtW emissions may also depend on how the photovoltaic solar panels or the cement used for the hydropower infrastructure are manufactured.

Even within the same production pathway, a fuel’s impact may change depending on how it is delivered. A fuel produced with renewable energy but transported over long distances to its final use point may have higher WtW emissions than a fuel produced and used locally. For example, e-methane produced from solar panels and transported over long distances in a cryogenic state will, in general, have greater WtW emissions than locally consumed e-methanol produced from a wind farm.

The complexity of measuring emissions

The downstream components of WtW calculations vary according to each ship’s design. TtW outcomes can, for instance, be impacted by using fuel cells, combustion engines, turbines, or the installation of emission abatement technologies.

Additionally, in the case of ammonia, for which no engines are currently commercially available, the impact of nitrous oxide (N2O) emissions on overall GHG emissions remains uncertain. This creates the potential for a new emissions problem. According to the Intergovernmental Panel on Climate Change, N2O has a 100-year GWP 273 times higher than CO2’s.

Hydrogen is an indirect greenhouse gas, reacting with other GHGs in the atmosphere to increase their GWP. A recent UK government study has estimated that fugitive hydrogen has a GWP of between 6.0 and 16 over 100 years.

In addition to GHG emissions, understanding air pollution from NOX, sulphur oxides (SOX) and particulate matter is essential when assessing alternative fuel contenders. These pollutants can affect climate change and also have a direct impact on human health. LNG, liquefied petroleum gas, and methanol all significantly reduce air pollution. Theoretically, SOX emissions could be reduced by 99%, though a small amount will be emitted from the pilot fuel

Photo: Canva

used in combustion (between 1.5% to 5% of pilot fuel used in dual-fuel engines).

The ethics of biofuels

Biofuels have low SOX emissions and are a turnkey solution that can be used in existing engines with some precautionary measures and offer immediate CO2 emission reductions. Biomass to make biofuels is theoretically available everywhere, limiting the transportation required for distribution. They can also be used in blends with fossil fuels to reduce emissions without needing modifications to a vessel’s tanks or engines. In an ideal scenario, with production increasing sufficiently, ships could refuel sustainably at any port. However, the feedstocks and factories for producing second- and third-generation biofuels need further development to supply the necessary volumes – and here, too, examining production pathways is essential.

Sustainable development requires an integrated approach that encompasses social and environmental concerns, which is a major consideration for the uptake of biofuels. The biomass used to make them must itself be produced sustainably, as the first step in the biofuel supply chain. Yet, there is currently no globally accepted standard or certification available to broadly assess the sustainability credentials of biofuels from end to end.

Additionally, certain resources that can be used as biomass, such as fields, forests and crops, may be needed to meet other, more basic human needs. First-generation biofuels, produced from purpose-grown food crops, may create undesirable competition with food markets. Extra biofuel demand could also spur additional land to be converted for feedstock cultivation. The ethical allocation of resources is fundamental to the concept of sustainability and, therefore, should be non-negotiable when planning biofuel supply chains and production.

Then again, developing the needed infrastructure to produce advanced biofuels (second- and third-generation) using mostly waste materials from forestry activity and agricultural residues could be seen as an opportunity to create jobs locally and build a sustainable bio-economy.

The real climate impact of new fuels

Decarbonising the maritime sector using new fuels will require a tremendous amount of low-cost renewable energy. Based on average e-fuels production efficiency of 50%, it is estimated that the shipping industry would today require 20-24 exajoules of renewable electricity if e-fuels were to replace all fossil fuels used by the entire shipping sector (the global primary energy consumption totted up to about 600 exajoules in 2019, of which some 9.0EJ came from wind & solar).

Large-scale access to renewable electricity will be pivotal to producing e-fuels and hydrogen. Additionally, a cross-sector approach will be needed to share resources such as wind and solar power between maritime and other sectors. In addition, ammonia (and therefore hydrogen) is used in fertilisers and is vital to securing the world’s food supply.

This sort of a consideration is beyond the scope of WtW calculations but necessary to achieve true sustainability. Given the complexity and importance of the task of decarbonising shipping, the best way forward is to collaborate: to share knowledge and resources across the industry and beyond, having the complete picture of what real impact new fuels will have on the climate. ‚

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