A controversial new road and tunnel crossing the Thames estuary would replace diesel-operated vehicles with versions fuelled with hydrogen during the construction phase, National Highways has announced. The government-owned company has launched one of the UK’s largest ever purchases of low-carbon hydrogen for the Lower Thames Crossing, saying it will “reduce the carbon footprint of the Lower Thames Crossing, accelerate the construction industry’s shift away from diesel, and kick start the highly anticipated development of a hydrogen ecosystem in the Thames Estuary”. 
National Highways is tendering for supply, storage and distribution of over 6kt of hydrogen to use on the project, which will replace around 20 million litres of diesel. Although projects such as HS2 have trialled small hydrogen generators, the Lower Thames Crossing would be the first in the UK to use the fuel on a large scale to power its major construction vehicles such as excavators and dump trucks.The project also plans to use electric plant for static or slow-moving machinery, where a mains connection is possible and in smaller equipment where battery solutions are viable.
The Lower Thames Crossing is now under consideration by National Infrastructure Planning and a decision on development consent is due in spring 2024.
The move would be a step change for the construction industry and builds on the work of the Construction Leadership Council’s CO2nstruct Zero task force, which recently published its government-backed route map to eliminate diesel from most construction sites by 2035.
Traditionally the industry has been reliant on diesel to power heavy machinery which are hard to electrify and not suitable for batteries due to their significant power requirements. National Highways says that securing the supply of such a high volume of hydrogen will give its supply chain the confidence to invest in the next generation of hydrogen powered machines, as well as develop the new skills required to operate and maintain them. It also aims to kick start a hydrogen ecosystem in the Thames Estuary.  The Thames Freeport, which is directly adjacent to the proposed tunnelling compound has already been identified as a potential hydrogen supply site.   
National Highways summarised the Department for Transport policy on hydrogen combustion: hydrogen fuel cell technology produces zero harmful emissions at the exhaust (the only emission is water), is energy dense, recyclable and maintainable. Hydrogen internal combustion engines that burn hydrogen gas result in trace levels of CO2 and some nitrogen oxides and therefore cannot be classed as zero emission. However, hydrogen combustion used in non-road mobile machinery is not currently subject to zero emission phase out dates for zero emission vehicles.