While LNG is expected to be an early success, the picture becomes more diversified with time, as more than 20% of shipping could adopt hybrid propulsion solutions, featuring batteries, or other energy storage technologies, the class society said.
The main drivers for the use of alternative fuels are the desire to reduce greenhouse gas emissions and the need to meet upcoming air pollution requirements.
“The global merchant fleet currently consumes around 330 mill tonnes of fuel annually, 80-85% of which is residual fuel with high sulphur content,” said Christos Chryssakis, DNV GL senior researcher and position paper project manager. “Shipping must change and we must contribute technical measures, operational measures and alternative fuels to meet the challenges we are tackling.
In the long term, short sea shipping is expected to take advantage of locally produced fuels such as biogas, biodiesel, methanol, shoreside electricity and hydrogen. Deep sea shipping needs globally available fuels and so will tend towards LNG and biodiesel, if it becomes available. Nuclear energy suffers from public perception problems but may come to the fore sometimes in the future, if it will be perceived as a safe alternative.
“While renewable energy, particularly solar and wind, may have some potential to mitigate carbon emissions, this is not seen as a viable large-scale alternative for commercial shipping,” said Chryssakis.
An evaluation of well to propeller greenhouse emissions, rather than just shipboard potential to reduce emissions, demonstrated some major drawbacks for some of the options, as did an evaluation of potential availability. For example, the availability of land to grow biofuels is a significant barrier to its widespread use, with an area the size of Greece required to produce 50 mill tonnes of biodiesel.
This position paper contains a discussion on ways to overcome the challenges ahead during the transition towards a more sustainable future for shipping. “There is no doubt that adopting new technologies are likely to be a challenge for shipowners. DNV GL is leading the way through our technology qualification processes, which are designed to ensure that new technologies work as expected,” said Chryssakis.