Efforts to move Somerset waste vehicles away from fossil fuels have hit a snag after the prototype vehicle kept breaking down during a recent trial.

The Somerset Waste Partnership (SWP) is looking at ways to gradually replace its existing diesel-powered vehicles with more environmentally friendly alternatives.

Waste bosses announced in late-June that they would spend more than £5.5m replacing 22 waste vehicles, either by swapping them out for electric vehicles or refurbishing them to extend their service life.

But these efforts have encountered an obstacle after a refurbished electric waste vehicle exhibited "poor" reliability while being put through its paces on collection routes in Taunton and Bridgwater.

A report on the trial came before the SWP's joint scrutiny panel when it met virtually on Wednesday afternoon (December 7).

The trial vehicle, which is based at the SWP's Bridgwater depot, was designed to be "stretched to its operational limits" to see whether other waste vehicles could be refurbished in the same way.

Mike Cowdell, the SWP's customer experience manager, said in his written report that waste crews had responded positively to the vehicle, but that it had proved unreliable even on relatively unchallenging terrain.

He said: "Much of the feedback from crews using the vehicle have been positive, relating to less noise and vibration.

"The reliability of the vehicle has been poor, and significant maintenance has been required to ensure that the vehicle is operative.

"Issues have ranged from faulty battery packs to complex electrical issues, as well as run-of-the-mill issues with refuse collection vehicles.

"The more complex issues have required specialist knowledge have resulted in the vehicle being withdrawn from service for considerable periods of time and returned to Magtec (the fitters) for specialist repair.

"This has slowed down the pace at which we can trial the vehicle – noting that it takes the weeks to trial one vehicle's full route, given the three-weekly refuse cycle."

The reliability of the electric refuse vehicle is affected by numerous factors, with terrain, temperature and the use of wipers and heaters all causing a drain on the batteries (which themselves degrade over time).

The average range of the electric vehicle on a single charge was 79 miles – with the longest it was able to travel being 102 miles, and the shortest distance being under 70 miles.

Mr Cowdell said: "Crews operating the vehicle have taken returning to the depot for lunch breaks or after tipping to recharge the vehicle to ensure that the round is completed.

"This behaviour is adopted when the round length is greater than 80 miles, or when the crews have had concerns surrounding the vehicles capacity to complete the round. This activity generally provides an additional ten to 15 per cent of charge to the vehicle.

"On average, the vehicle can achieve 79 miles on a single charge in an environment with moderate changes in terrain and in fair weather."

The SWP is currently carrying out a separate trial of running its fleet on hydrogenated vegetable oil (HVO) instead of diesel, in a short-term bid to cut carbon emissions before a large number of the vehicles need to be replaced outright.

A report on the outcome of this trial is expected to come before the Somerset Waste Board in February 2023.