London’s green Routemaster buses running on diesel alone

London’s 21st Century Routemaster buses may not be as green as you are led to believe.

Reports are circulating that a flaw with the electric battery means the vehicle TfL claims to be “the most environmentally friendly bus of its type” is running on diesel alone.

Read more: The Apple Pay effect: TfL warns of fines for dead batteries

It has been confirmed that approximately 80 of the new Routemasters are using diesel, while a total of 200 have needed replacement batteries. It is thought that the batteries have been a problem for some time, with reports of failures emerging in March.

Running on diesel alone, rather than a hybrid electric approach, is not only bad news for environmentalists. Lacking the electric battery pack, buses are slower and acceleration is reduced as the diesel engine struggles to cope on its own.

The BBC reports that a number of bus drivers have sent letters of complaint to Christian Wolmar, a transport journalist seeking to become Boris Johnson’s replacement as Mayor of London. One particular letter claimed that "the hybrid system does not work", that it is "very slow", "it just cuts out in the middle of the road" and drivers "don't feel in control of the bus".

John Murphy from the Unite union also believes that the hybrid buses have been a failure.

“The batteries just aren't fit for purpose. It's not that the technology isn't there it's just the wrong technology,” he said. “Personally I think this stems from the rush to get through this vanity project.”

Read more: TfL praised for mobile technology investment

Although the buses themselves are expensive, costing £354,000 compared to the £300,000 price-tag for a regular hybrid, they have all been purchased by TfL, not the bus companies. There are currently 500 in operation across London, with an additional 300 planned for launch in 2016. The replacement batteries, however, did not have to be purchased, as these were covered by the manufacturer’s warranty.