Reading Buses and the Gas Bus Alliance are aiming for the sky with a new fuel station for the operator’s biogas buses, which solves a problem relating to yard space at its centrally-located depot in the town
Sometimes not considered by advocates of alternative fuels is the impact that the equipment required for on-bus energy replenishment – of either batteries or tanks – has on depot space. And the latter is often a commodity that is in short supply.
Because of that, the Gas Bus Alliance (GBA) and Reading Buses collectively came up with a novel solution to that for the operator’s 62-strong fleet of biogas-powered vehicles: A gas station in the sky.
In a nutshell, a five-metre-high gantry with room for a double-decker to pass underneath is mounted on 15 pillars. 75 tonnes of equipment sits on the platform, including three compressors and 22 banks of high-pressure storage vessels. Dispensers stay at ground level.
Not only does that give ample capacity to fuel the existing fleet, but there is also considerable scope for expansion should the operator’s fleet of biogas buses grow. From an operational perspective, there has been no change to how the evening run-in is handled.
“Each compressor provides enough gas to fuel 40 buses per day. We always have a spare, although the load is spread equally,” says GBA Head of Sales and Marketing Tony Griffiths.
There is space on the platform for three more compressors, meaning that the station has been ‘future proofed’ to allow it to support Reading Buses’ whole fleet should it be converted to 100% biogas power.
Onward and upward
The platform-mounted fuelling station replaced a floor-level setup that occupied around 300m2 of space. Gas is still drawn from the low-pressure main, with a pipe routing it to the new platform and then upwards to the raised equipment.
There, it is dried and compressed. It then passes to the pressure vessels, which are grouped in three banks that are used sequentially to allow maximum use of the stored gas. The electricity substation that powers the compressors stays at ground level to give access to the utility company, but it could have been mounted on the platform if required.
The new station will be paid for in two ways. Reading Buses gained OLEV grant funding to cover some expenditure, and the remainder is incorporated into the pence-per-kg consumption charge made by the GBA as part of its standard billing process.
Part of the 10-year contract between the two parties involves repair and maintenance. To assist the GBA in that, the fuel station is fitted with telematics. It allows real-time monitoring of the compression rates and of the operating temperature and oil level of the compressors.
Although Reading Buses’ Great Knollys Street depot could be considered a tricky spot for an elevated gas fuelling station, the opposite was true. No problems were encountered with Network Rail despite the electrified Great Western Main Line passing within yards of the installation. The site’s previous use as a landfill site also posed no problems. Pillars were driven into bedrock.
Why elevated?
The idea for an elevated fuelling station came from a comment made by Reading Buses Head of Engineering and Innovation John Bickerton.
“We have made no upfront outlay on the gas station and it occupies no yard space. The financial argument is furthered by the GBA’s pricing model. The fuel costs of a biogas bus are 80% of those of a diesel, and we benefit from an index-linked fixed price,” he says.
“With that, I can accurately predict fuel costs well into the future. That’s impossible with diesel.”
For Reading Buses the saving on fuel is not of primary importance. It accounts for only around 10% of operating costs, and gas vehicles are slightly more expensive to buy than diesels.
But they are significantly more reliable like-for-like, adds John, and that is important.
When the overall equation is considered – a cut in energy and maintenance costs, a drop in lost mileage and reduced emissions offset against a higher initial outlay – gas comes out on top, he says.
The future?
Is elevation the solution for all new gas fuelling stations? If the operator requires, yes, but there is also an option to position it underground if that suits. Both complement the conventional floor-level installation.
“Although it looks futuristic when elevated, this is a simple concept. There is nothing new about taking gas, drying it, compressing it and fuelling vehicles with it. That technology has been around for nearly 100 years,” says Tony. When calculating the manner of installation, the GBA considers the peak filling demand, which typically occurs after 1900hrs.
“Mounting the gas station five metres in the air, as we have done at Reading, is a first for us. It is a proof-of-concept idea in a way, but nobody is a guinea pig. We know the technology and that this manner of installation works.”
The GBA takes responsibility for ensuring that sufficient fuelling capacity is provided. It builds redundancy into the filling station with an extra compressor and additional storage, and in a worst-case scenario it has road tankers to dispatch as contingency, says Tony.
“An elevated gas fuelling station is a statement to the industry. It allows us to overcome yard space issues and make biogas even more attractive,” adds John.
The new station complements the GBA’s four other UK gas fuelling station. Two more are to come on stream in the New Year. “It demonstrates our commitment to installing and operating the UK’s largest gas fuelling network with all its environmental and commercial advantages,” concludes Tony.
