New paper examines the use of electrofuels to decarbonise deep-sea container ships
The latest paper from Circular Economy Energy and Environmental Systems (CEEES) group in University College Cork led by Nathan Gray and co-authored with Richard O’Shea and Prof Jerry Murphy of UCC, Beatrice Smyth of Queen’s University, Belfast & Piet Lens of University of Galway examines the use of electrofuels to decarbonise deep-sea container ships.
A few key insights:
Cargo space: Because all of the fuels assessed in this paper have a lower energy density than fossil maritime fuels, cargo capacity must be sacrificed if vessel operators wish to maintain the same sailing range as current vessels. Depending on the fuel, this could range from 3% to 16% of the vessels cargo capacity. Fuels that require complex storage systems, such as methane, ammonia, and hydrogen sacrifice larger amounts of cargo space than fuels that are liquid, such as methanol. If vessel operators wish to maintain cargo capacity, energy storage can be downsized but this will require more frequent refuelling and a change in vessel operations.
Costs: The cost associated with the use of electrofuels depends on which lens you view them through. From the perspective of a vessel operator, the greater vessel capital costs and higher fuel costs results in an increase in total cost of ownership of between 124% and 731% depending on the fuel. Fuels that require complex storage (methane, ammonia, hydrogen) results in larger cost increases than liquid fuels (methanol). A minimum carbon price of €400/tonne is required to make these fuels economically competitive with fossil maritime fuels. From a consumer perspective, the use of electrofuels could add as little as €0.48 to the final price of a laptop, due to the very high efficiency of transporting goods by sea. This indicates that there could be the potential for vessel operators to charge a premium on goods transported using decarbonised shipping without dramatically increasing costs for the end user.
Emissions: The environmental impacts of electrofuel production is largely driven by the carbon intensity of the electricity used in the electrolysis step. To produce electrofuels that result in a 70% decrease in greenhouse gas emissions compared to fossil maritime fuels, an electrical carbon footprint of 40 gCO2/kWh is required. This implies that direct connection to a source of low-carbon electricity is needed for sustainable electrofuel production. In areas where the carbon intensity of the electrical grid is lower than 40 gCO2/kWh, connection to the grid may be possible but the extra load created by electrolysis must be matched by an equivalent increase in low-carbon generation otherwise the marginal source of electricity (often natural gas) will be used to meet the new demand, therefore negating any climate benefit from the project.
