Professor David Chiaramonti is looking down at the ground to help resolve a problem up in the sky: airplanes' emissions of carbon dioxide (CO₂) and other pollutants.

An expert in energy systems and power generation at the Polytechnic University of Turin in Italy, Chiaramonti wants land that is unused, marginal and degraded to produce clean fuels for jets.

Oil-rich plants

The fuels would come from oilseed plants such as Camelina sativa—native to Europe and central Asia—and replace kerosene, a fossil fuel that traditionally powers aircraft. Kerosene worsens climate change by releasing CO₂ and nitrogen oxides into the atmosphere.

Chiaramonti led a research project that aimed to increase supplies of the only type of sustainable aviation fuel currently available: hydroprocessed esters and fatty acids, known collectively as HEFA. Called BIO4A, the project wrapped up in mid-2023 after five years.

HEFA is a biofuel made mainly from used cooking oil and animal fat left over in meat production—sources that at best can meet 2% of aviation's fuel needs. Chiaramonti believes camelina, which is also known as false flax and grows in countries including Italy and Spain, can help overcome this bottleneck without impinging on crops grown for food.

"We focused on very poor soils—on land that is very dry and arid and lost to food production, but which could be recovered," he said.

As a result, camelina offers the prospect of increasing overall HEFA quantities and of addressing soil degradation, which plagues many countries especially in the Mediterranean region as a result of climate change and intensive agriculture.

"The biggest problem in sustainable aviation fuels today is sourcing sustainable lipids," said Chiaramonti, who is also president of an Italian renewable-energy research organization called RE-CORD. "We investigated how to produce sustainable lipids in marginal, degraded land."

Sky-high emissions

The global aviation industry's emissions of CO₂ have risen faster in recent decades than those of the road, rail and shipping sectors. Aviation now accounts for 2%–3% of global CO₂ discharges.

What's more, unlike with road and rail transport, electricity has yet to emerge as an option for aviation in general because battery technologies can currently power only light aircraft such as drones.

That intensifies the spotlight on sustainable aviation fuels, also known as SAF.

In October 2023, the EU's national governments approved legislation that will require suppliers of aviation fuels in Europe to ensure a SAF market share of at least 2% in 2025, 6% in 2030 and 70% in 2050.

The law is part of a major package of European legislation that underpins an EU goal to slash greenhouse-gas emissions by 55% in 2030 compared with 1990 levels. The 55% reduction target is more ambitious than a previous EU plan to cut emissions by 40% over that period.

Traditional success

HEFA has a similar chemical structure to fossil fuels, easing the task of making it fit for jet engines.

Even as they tested unused land to make HEFA from camelina, the BIO4A researchers advanced traditional production methods.

The project used a refinery that makes HEFA from waste cooking oil and animal fat left over from meat production at a full industrial scale.

This focus explains the participation in the project of two major European oil companies: Total in France and Italy-based Eni.

"We produced 1,000 [metric] tons of HEFA from residual oil, which so far was the largest volume ever produced industrially in Europe in the framework of the EU's research program," Chiaramonti said.

This article was originally published in Horizon, the EU Research and Innovation Magazine.