The Department for Transport is committed to reducing emissions of both air quality pollutants and greenhouse gases from road transport, for example through setting of performance requirements for new vehicles. We welcome developments which assist in the meeting of those commitments, but do not generally provide support for development of specific technologies. Rather we leave industry free to develop the most effective technologies to meet the performance requirements we set.
We are not aware of anyone currently proposing the use of a mixture of oxygen and hydrogen gases as a fuel for road vehicles. We are, however, frequently approached by companies marketing "hydrogen on-demand" systems which produce small quantities of this gas mixture on-board the vehicle, to feed into the inlet air. This is claimed to reduce fuel consumption and emissions of pollutants.
As with other proprietary products claimed to deliver fuel consumption benefits we recommend that companies commission objective testing to support the benefits claimed in the marketing of their products. The Department has not, to date, seen any objective evidence that hydrogen on-demand systems for retrofitting to engines actually produce such benefits.