By Johnny Sharp

No sooner has optimism grown around alternative fuels than research emerges to cast doubt on them. For instance, ammonia has been proposed as a potential green fuel in the maritime sector, but in July a study from MIT found that it could worsen air quality further and impact public health.

“Just because it is carbon-free doesn’t necessarily mean it is ‘clean’ and good for public health,” said MIT’s Anthony Wong, lead author of the study. 

Meanwhile, the government (particularly the recently departed Conservative administration) talked up nuclear power as an energy source for the future but outside a select number of trains and buses globally, its use as a general passenger vehicle fuel seems limited. Meanwhile, bio-CNG (compressed natural gas) and LNG (liquefied natural gas) are renewable and efficient options, but some reports claim the latter releases more nitrogen oxides compared to diesel.

Currently, higher hopes surround the potential of HVO (hydrotreated vegetable oil), a low-carbon biofuel made from plant waste, oils and fats. Earlier this year, London Gatwick claimed to have cut carbon emissions from its diesel vehicles by 90 percent by swapping to HVO, while leading infrastructure services company FM Conway has also embraced it, using HVO alongside solar power on flagship projects such as their resurfacing of Elmfield Way in Maida Vale, north west London. They now have plans to move their whole fleet over to HVO.

Image: Joanna Gilroy, UK Director of Sustainability; credit: Balfour Beatty

Big benefits but limitations

Not everyone is convinced, though – one such questioner being Joanna Gilroy, UK Director of Sustainability at Balfour Beatty. When looking into alternative fuels for use on a major project upgrading the M77 in Scotland, the civil engineering giant sought an independent verdict. 

“We actually came together with some of our peers,” she says. “And we co-funded an independent study conducted by the Supply Chain Sustainability School in order to understand: is HVO really the solution?

“The fundamental conclusion was, while HVO can be part of the solution mix, the supply chain around it is not transparent enough: where are the sources of the fuel coming from? Are you displacing them in the supply chain? We can't get deep enough into where the vegetable stock is coming from to be sure of that.”

Another issue. from Balfour Beatty’s point of view, is availability, she says: “When you look at the sheer amount of fuel that is used in the construction sector, you're talking millions of tonnes, so can we get enough supply from sustainable sources?”

Balfour Beatty have instead been trialling use of hydrogen in partnership with the Scottish Government and other partners on the M77 project. “For us, it’s the best like-for-like replacement for diesel,” Gilroy explains. “And you can use it in a form where it you retrofit. And this is actually what we've done on the M77 project: the Scottish Government provided half the funding for us to retrofit two of our gritters and two of our support vehicles as well. So, they’re standard diesel engines, but we've added in the ability for the vehicles to use hydrogen gas to displace some of the diesel.”

However, availability and affordability are still issues just as with other alternatives. “Our European counterparts are much further ahead of the UK on this. They’re manufacturing hydrogen from multiple different sources and making it more readily available and affordable,” Gilroy says.

She also points to other products that can be blended into the existing fuel mix.

“We are currently working closely with Syntech, a manufacturer of drop-in biofuels [such as Syntech ASB, a B100 biodiesel]. Their raw material is sourced from the London restaurant and hospitality sector. It’s shipped to them in their location by barge and they process everything on site,” enthuses Gilroy.

Ultimately though, Gilroy sees a future for sustainable fuels based not on one solution, but several: “We're going to have to draw on multiple fuels, along with solar, wind and other sources of renewable energy because there is no one-size-fits-all solution.” 

Newsletter image: Aerial image of the A77 and M77; credit: Shutterstock.