Ian Pratt of JCB has described on 26 January how the new JCB combustion engine replaces diesel fuel with hydrogen to power construction vehicles. The engineering team of around 100 has now produced dozens of the new engines that are being tested in excavator vehicles working in Staffordshire quarries. NOx emission is claimed to be reduced by operating at low cylinder pressures. This is a tough challenge because NOx is easily formed by reactions above 1000 Celsius. JCB had previously built and operated two hydrogen-fuel-cell diggers, but formal comparisons of performance with hydrogen-diesel vehicles have not yet been released.