Most obviously, future cargo ships dispense with crew quarters, so Rolls’s sketches for autonomous vessels allow for containers to be stacked, and fuel burned, more efficiently – up to 15pc more efficiently.
Such savings add up given that there are 96,000 merchant vessels in the world, carrying around 90pc of global trade that is relentlessly growing. Container port traffic rose from 225m TEUs in 2000 to 792m in 2018.
According to the International Chamber of Shipping, maritime trade accounts for 3pc of global greenhouse emissions, emissions which the International Maritime Organisation, has vowed to reduce by 40pc by 2030 and 70pc by 2050.
Unlike cars, however, much of that emissions reduction will have to be achieved by sleeker ship design, smart navigation (using currents and tides), and even upgrading propellers rather than batteries.
Recent calculations show that to complete a 31 day-trip from Asia to Europe the OOCL Hong Kong would need to carry more than 100,000 metric tons of batteries – 40pc of its cargo capacity.
Volume is the critical limiting factor for a move away from bunker fuel. Studies have shown, however, that – as in aviation – hydrogen fuel cells, where gases are combined to produce electricity, could deliver enough energy in a small enough volume to get round this difficulty, even for the world’s largest ships.
Though it would require a huge reinvestment in infrastructure, some countries (notably Japan) are investing heavily in liquified hydrogen, hoping that one day it will be a fuel as widely used as petrol.
We are all familiar with oil container ships. Last December the Japanese Suiso Frontier became the first vessel built to carry large quantities of frozen liquid hydrogen. Liquefying hydrogen reduces its volume by a factor of 800.
Road and rail
What about overland? At the moment, only about 1pc of goods are moved between Asia and Europe on trains. But huge, long-distance overland convoys are growing in popularity, notably at the top of China’s governing party, which is committed to a vast infrastructure programme across Eurasia known as Belt and Road.
Rail is almost twice as fast as ship, and cost has fallen from 13 to just five times that of maritime freight. Meanwhile the trend towards bigger, cleaner and partly or fully autonomous trucks could blur the line between road and rail.
Big, articulated High Capacity Vehicles (HCVs, weighing up to 70 tons) are calculated to halve the number of heavy goods vehicles on the road. And a majority of experts in the road haulage industry surveyed recently said they expect autonomy to allow so-called “truck platooning” – close packed road trains – by 2030.
But fuelling such vast vehicles cleanly is a headache. Given that the majority of road freight occurs on a tiny proportion of the road network, however, power could end up being delivered through new roads themselves – known as Electric Road Systems.
But they will take years to built. In the interim, self-powering electric trucks are the talk of the town. Valuations are high: $370bn (£278bn) for Tesla, maker of the Semi, $15bn (£11.2bn) for Nikola, a rival which has yet to sell a single unit.
