Brighton gears up for new fleet of solar-powered buses

The bright yellow Big Lemon buses are a familiar sight – and smell – on the roads of Brighton and Hove. For nine years the Community Interest Company has run all its vehicles on waste cooking oil from local restaurants, recycled into biodiesel, but now it wants to go one step further.

The Big Lemon wants to install solar panels on the roof of its east Brighton depot, storing the energy in batteries and charging buses overnight. It is working with the Brighton Energy Cooperative (BEC) towards a vision of zero emissions bus services in every UK community by 2030, using Brighton as a pilot.

The Big Lemon eventually wants to replace its 10 biodiesel buses, which are not suitable for conversion, and has already raised £250,000 of investment in a bond issue to do this, exceeding the original target of £100,000.

The company has also been shortlisted for the M&S Energy Community Energy Fund, which could bring up to £25,000 through a public vote and pledged donations from voters – the cost of the solar panel installation at the depot. The project is currently leading votes in the south and more than £9,490 has been pledged.

UK’s first solar buses

Although this is the first UK initiative of its kind, there are examples of electric buses across the country, including in London and Harrogate. The government has put £30m of funding towards helping bus operators and local authorities in England run more low-emission buses.

“Electric bus technology has progressed quite far. We wanted to try that and embrace it,” says Tom Druitt, managing director of The Big Lemon. Biodiesel has a low carbon footprint but there are still emissions from the buses. Using electricity means almost no emissions.

The key thing about The Big Lemon idea is that the energy will be generated on site. “If we run on mains electricity then we still have a large carbon footprint,” says Druitt, who is also a Green party councillor.

The Big Lemon has decided to convert diesel buses to run on electric, instead of buying brand new electric buses. Work has begun on the first buses which were purchased for £20,000 each. With conversion costs of £140,000 each, Druitt says this approach is still cost effective as, depending on the brand, a new electric bus would cost between £250,000 and £500,000. Conversion also allows the company to have more say in the bus’s specifications.

Druitt estimates that The Big Lemon will save around £20,000 a year in fuel costs, as well as a reduction in maintenance costs. “We’ve estimated that there’s a six-year payback on these buses and we’re calculating for an eight-year life span, so essentially we get two years free,” he explains.

The panels for the initial project will generate 30,000kWh of electricity and will power the whole of the 52 route between Woodingdean and Brighton city centre. The Big Lemon wants to power all five of its routes this way eventually while its coach fleet, used for longer distances, will continue to use waste cooking oil due to a lack of available technology.

Can it be replicated?

How easy will this idea be to replicate elsewhere? Chris Jardine, technical director of solar energy experts Joju Solar, says that in theory it should be easy. “I think the intricacies will be in whether you can get enough energy from the solar to fully power the fleet,” he says. “It may be easy in summer, while in the middle of winter you might be getting five times less electricity out of your solar panels.

“By not putting it into the grid it makes it a bit more difficult as you come across this commonly found issue with renewables, that they’re intermittent,” says Will Cottrell, chairman of BEC. “You need to think quite hard about how it works technically,” he adds, explaining that getting the right size battery and overall system is key to providing the right level of supply.

“But this is the way it’s got to be,” he says. “To move us away from a centralised energy system we need to move away from a centralised grid as well, so we need to understand the technology that is going to enable us to do that.”

The plan for The Big Lemon is to produce enough energy in the winter, and an excess in summer but it will have a mains backup if needed. The team can then use any excess energy in the summer to give energy to the building.

“I think our independence, background and philosophy generally makes it easier for us to try these things,” says Druitt. “That’s what all our stakeholders signed up for really, we don’t have an angry mob in an AGM.”