Presenting the case for biogas

24

Electric continues to be pushed as a means of achieving Britain’s carbon zero goals – but alternatives still have their place

Experimentation in alternative propulsion is not new. One of the most important trials in the application of alternative fuels took place in Lille, Northern France, almost 30 years ago. The fuel was biogas.

A programme to use biogas in a sustainable urban bus fleet was pioneered by Lille Metropole in 1990. Powered by gas captured from fermenting sludge at a local sewage treatment plant, in 1994 the first four dedicated vehicles were put on the road with the goal to replace the entire fleet. With the rest of the waste used as compost, it was a true virtuous cycle.

Similar pictures exist across the continent. Gas buses operate across from Spain as far as Norway, reducing greenhouse gas emissions, roadside pollution and noise. Yet in Britain, according to gas infrastructure provider Roadgas, the conversation on biogas as alternative fuel is limited – and it says this could have dire consequences for zero-carbon ambitions.

The case for gas

Roadgas designs, installs and maintains infrastructure for compressed natural gas (CNG), liquid compressed natural gas (LCNG) and biogas operations. It has had recent success in the bus market – it is in the process of finishing off phase two of an investment by Nottingham City Transport (NCT) into a fleet of 120 double-deck biomethane buses. NCT buys 100% renewable and sustainable biogas gas, generated through anaerobic digestion, directly from the supplier. It boasts a reduction of 84% in CO2 emissions in its fleet as a result, as well as a reduction in NOx and particulates.

One of the strongest arguments for biogas is its ease of application for back-to-base fleets. Managing Director of Roadgas David Rix and Operations Director Jon Harman explain that two major changes in the market have made this technology viable today.

The first was the widespread availability of biogas (biomethane) as a fuel – which adds a CO2 benefit over fossil methane (both fossil methane and biomethane offer reductions in particulates and NOx). The second change began when the OEM introduced dedicated spark ignited CNG vehicles.

Gas in action

There is no better way to demonstrate the practicality of gas in application than at the Nottingham bus depot.

Each night, 200 vehicles are pulled off the road and parked nose-to-tail to be rolled out again the next day. The order in which they are parked, as well as the time spent refuelling them, is critical.

“We had to make sure gas could match the fuelling profile of diesel,” explains Mr Harman. “In the depot setting, biogas lets buses function the same way as their diesel counterparts.

“If they spend more than a few minutes refuelling point, the queue of buses can potentially back up into the main city thoroughfare.” Jon questions the use of electric: “Imagine the logistics of putting them on EV charging points. And where would you put the infrastructure?”

The dedicated biogas buses, built by Scania, have wi-fi, USB ports, and air conditioning. Gas is stored in cylinders onboard. Roadgas says passenger feedback is extremely positive, and the drivers’ experience is near identical to that of the diesel fleet.

Reading Buses and First Group Bristol have also embraced gas into their back-to-base fleets, while Roadgas also maintains the depot for Stagecoach in Sunderland. Combined with extensive gas transport operations across Europe, it is hard evidence of what gas can achieve in this sector.

The emissions debate

A back-of-the-envelope calculation in 2012 concluded the impracticality of recharging NCT’s 200 buses on electric every night, both for grid and infrastructure demands.

The conversion to gas, meanwhile, was relatively painless. But the government focus on electric and carbon zero is pushing gas out of the framework for many operators.

“Many may be sitting on the fence because they don’t know what will work for them,” says Mr Harman. “There are conflicting messages with electric and gas. This is down to limited government focus for gas in the transport sector as well as a lack of awareness of what gas can achieve.”

It is clear the focus on tailpipe emissions is driving the current shift to electric. But that is irrelevant, according to Roadgas. “Well-to-wheel and lifespan need to be considered,” Mr Harman explains. “We are now working towards a net zero road map. Currently biomethane offers an 84% CO2 reduction.

“The remaining 16% is the processing cost, including electricity required to compress the gas. As electricity therefore becomes increasingly carbon neutral, so does the processing cost, potentially increasing the 84% CO2 reduction to 100% in the future.

“So far, well-to-wheel studies have demonstrated that gas has a lower carbon footprint than electricity.”

Mr Rix adds: “The debate shouldn’t even be gas against electric. It should be gas and electric against diesel. They both need their place – but for many in the electric lobby, gas has no place. That is keeping just diesel vehicles on the road.”