Biofuel use needs to increase to help fight climate change as liquid fuels will be needed by aircraft and ships for many decades to come, finds a new report requested by the UK government.
The Royal Academy of Engineering report says, however, that some biofuels, such as diesel made from food crops, have led to more emissions than those produced by the fossil fuels they were meant to replace. Instead, the report says, rising biofuel production should make more use of waste, such as used cooking oil and timber.
Ten years ago biofuels were seen as ideal, low-carbon, replacements for the liquid fossil fuels that power the majority of the world’s transport systems. But concerns grew that first-generation biofuels, made from food crops, were increasing food prices and were often as polluting as fossil fuels when all factors in their production were considered.
The new report combines more than 250 analyses of the impact of biofuels around the world, including how demand for food-based biofuels drives the destruction of forests and peatlands when farmers expand into additional areas – the most contentious issue.
It also warns that the promise of clean biofuels from algae remains far off, with current versions much worse than diesel. The researchers found that when land use changes were accounted for, all the significant types of biodiesel – palm oil, soybean, rapeseed and sunflowers – caused more carbon emissions than diesel itself.
Accounting for land use change is complex, but even if this factor is ignored only palm oil has led to a reduction of 50% in emissions compared with diesel, the level required by EU rules.
Bioethanol, which replaces petrol (gasoline) and is produced from corn, wheat, sugarcane and sugar beet, failed to meet the 50% reduction when land use change was included. Wheat-based bioethanol was the worst performer, actually producing more carbon emissions than petrol.
By contrast, the use of waste from farms and forestry, and from used cooking oil, to make biofuels, always cut emissions compared with the performance of fossil fuels. In some cases, such as using waste stalks and cobs from corn, biofuels could have near-zero emissions overall.
Under the Renewable Transport Fuel Obligations order, biofuel must be blended into petrol and diesel in the UK today at a rate of 4.75%. A rise towards the 10% EU-wide target by 2020 has stalled due to the environmental concerns. The authors says their report is intended to break that impasse.
“Overall our evidence [is] that the sustainability risk of increasing levels of biofuels can be managed and the government should be confident of increasing the mandate for biofuels,” said Nilay Shah, a professor at Imperial College London and one of the team who produced the report. In the future, non-food crops such as miscanthus grass, could be grown on poor quality land, he said.
Wheat is an important source of bioethanol in the UK, with crops covering about 99,000 acres (more than 40,000 hectares) in 2015-16. But it is not clear if the land use changes that make wheat a poor biofuel apply in the UK, as the study combined data from all over the world.
The 2020 target was going to be missed, both in the UK and elsewhere, said Shah, as ramping up production in a sustainable way would take time. “That would be a big challenge – realistically it is a five- to 10-year timescale,” he said.
Despite the fast growth in electric cars, Shah said biofuels would be needed as a key part of tackling climate change because no significant alternatives for liquid fuels were available for aircraft, ships and long-distance HGVs. “The scope for electrification is quite limited for at least several decades.”
Progress towards producing better biofuels has been challenging. British Airways abandoned a £340m scheme to create jet fuel from London’s rubbish in January 2016, although in the same month the US navy launched its first aircraft carriers powered by biofuels.
James Beard, a climate and energy specialist at the World Wildlife Fund (WWF-UK), said: “Unsustainable biofuels can do more damage than good and should be phased out. But not all biofuels are bad. Certified sustainable biofuels will be needed in sectors that are tricky to de-carbonise, like aviation.”
John Sauven, executive director of Greenpeace UK, said: “While those promoting biofuels start with good intentions, the tendency, especially when it comes to land use, is for things to go horribly wrong. A much safer way to cut emissions is promoting energy efficiency, electric vehicles, and looking at mobility in a much broader way than just how to fuel people’s cars.”