New IRENA Report

Biofuels (report extract)

Biofuels are not yet extensively used in the shipping industry, yet they could play a vital role in its decarbonisation. Compared to fossil fuel alternatives, they offer smaller GHG, NOx and SOx emissions and they do so at relatively limited cost, due to their high technical compatibility with currently available shipping and bunkering infrastructure. Additionally, due to their biodegradability, they are safer for the environment in the case of spills, when unblended.

There are several commercial marine engine technologies that are able to operate on liquid biofuels. These can be blended with existing marine fuels, e.g. 20% FAME blends, which are widely available (IEA, 2017), and ISO 8217:2017-compliant 7% FAME blends, which are also commercially available. Some biofuels are even compatible as drop-in fuels.6  Table 3 (in report) shows some of the main biofuel alternatives and their applicability.

Marine diesel engines commercially available today are already capable of operating with certain biofuels, such as SVO, HFO, FAME, FT-diesel and pyrolysis oil, with little to no modifications necessary, depending on the fuel and the blend. The use of these diesel-like biofuels does, however, raise some fuel-specific issues. These include reduced engine lifespan, due to carbon build-ups in the case of SVO, or in the caseof FAME, water contamination, which could lead to loss of efficiency, microbial growth7
and fuel gelling. HVO solves some of these issues, however, due to its low oxygen content, higher fuel efficiency and longer lifespan. A switch to these fuels would not require changes to current storage and bunkering infrastructure or logistics (Balcombe et al., 2019; Hsie and Felby, 2017), making them an excellent option
for the short, medium and long term. 

For the full report read here.