
Electricity [TWh/yr] required globally to provide green fuels for all shipping segments where actual data uncertainties are included.
A newly published academic article addresses the availability of green alternative fuels for marine shipping (and aviation). The article makes a compelling case for nuclear propulsion or otherwise see freight will stay fossil in the foreseeable future.
The paper presents some basic realities of replacing fossil fuels in shipping with green alternative fuels for the same amount of work being performed. The required amount of electric power for producing these green alternative fuels is subsequently calculated. Compared on a scale equal to major industrial entities globally, it is proven beyond any doubt that there is basically not enough electricity in the world to make a relevant amount of green alternative fuels for shipping.
Basically, the gravimetric energy densities are orders of magnitude too low, or the thermodynamical losses are too high, for electricity to replace fossil fuel in this particular application. This finding also questions the conventional wisdom of the merit of an all-encompassing electrification of society. There are, however, niches where a relevant supply of green alternative fuels is possible to secure, albeit difficult.
Therefore, much of today’s research on green alternative fuels rests on a hidden assumption—that there will be available fuels. However, green alternative fuels will not be available in relevant quantities unless the research is well contextualized for small ships on short, domestic distances. The fuel availability is, therefore, a key constraint to incorporate in future work on green alternative fuels for shipping.
Furthermore, it seems prudent to open up a wider search for solutions, including nuclear propulsion, based on the fact that the gravimetric energy densities are physical realities that we must respect.
Source: Emblemsvåg, J. A Study on the Limitations of Green Alternative Fuels in Global Shipping in the Foreseeable Future. J. Mar. Sci. Eng. 2025, 13, 79.
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