Ambulances in Yorkshire have been fitted with methanol fuel cells to charge paramedic equipment while the engine is switched off.
The trial is part of a plan by Yorkshire Ambulance Service to cut the fuel consumption of its fleet by 30% by 2015.
According to the ambulance service, the technology could help the NHS save a gallon of fuel for every five hours that the engines are switched off, a saving of 12kg of CO2. Currently, engines must be left running while at an accident in order to keep emergency equipment charged.
The trial comes as Mick Farmer, assistant director of fleet at Yorkshire Ambulance Service NHS Trust, won Public Service Fleet Manager of the Year at the Green Fleet Awards.
Mr Farmer led the trust to be the first ambulance service in the UK to participate in the Carbon Trust Carbon Management Programme.
He said: “Due to the nature of the work of our service, the impact on the environment is a high priority and the challenge to reduce carbon emissions is huge.
“So far, in a bid to help reduce fuel consumption and, in turn, reduce the carbon footprint of the Trust, we have taught our staff eco-driving techniques and purchased frontline vehicles which are more economical and efficient. However, we will continue to find ways of reducing public spending on fuel and of becoming a greener, more efficient organisation.”