Green submarines

sir – The news that Britain is to develop hydrogen-powered driverless “green submarines” to carry freight around the country (report, September 15) is unlikely to have our truck drivers and seafarers reaching for their periscopes any time soon.

Both cargo-carrying and hydrogenpowered submarines have been around since the First World War. Today, the German and Italian navies operate Type 216 hydrogen-powered submarines. However, in an interview with the Today programme, the chief engineer of the manufacturer Ocean Waves revealed that his submarines could only carry only 21 tons of cargo, equivalent to one standard 20-foot container.

Given that Type 216 submarines are estimated to cost €280-560 million each, or about double the cost of a 24,000-teu (20-foot equivalent unit) containership, the economies of scale require some thought.

Captain Peter J Newton

Chellaston, Derbyshire