When a South African Airways Boeing 737 took off from O.R. Tambo International Airport in Johannesburg, South Africa, two years ago, headed for Cape Town, it was powered by an unusual fuel: tobacco.
South Africa hasn't yet repeated the jet biofuel feat, but in an effort to cut its climate-changing emissions and promote greener power the country's researchers are looking for innovative ways to manufacture green aviation fuel at larger scale.
A new "Waste to Wing" project aims to one day produce a significant share of the country's aviation fuel from waste plants, including invasive species.
“South Africa produces a large amount of agricultural waste, as well as waste from plantation forestry and waste biomass from alien vegetation clearing programs,” said Tjasa Bole-Rentel, an energy economics and policy specialist for the World Wide Fund for Nature (WWF), one of the groups involved in the biofuel push.
So far the effort is a small “proof of concept” project, likely to produce just enough jet biofuel for one more flight, she said.
But if the technology works, production could be scaled up significantly – perhaps to as much as 15 percent of the aviation fuel used at Johannesburg's international airport, she said.
Finding clean fuel for planes, ships, and other forms of transport hard to plug into a clean energy grid remains one of the biggest challenges for reducing climate changing emissions.
But as airlines face increasing pressure to become more sustainable, countries around the world are trying to find solutions, from hydrogen powered barges to, in South Africa's case, planes that could fly on weeds.
Scaling up jet biofuel – and making it cost effective – hasn't been easy, however.
Farmers in South Africa’s Limpopo province today continue growing solaris, a nicotine-free tobacco that produces large amounts of oil and that was used as a feedstock for the country's first tobacco-powered flight.
But “there is no local refining capacity available and the sheer scale of farming needed to make the economies of scale work at this moment in time” is difficult, Merel Laroy, a spokesman for SkyNRG, a Netherlands-based alternative jet fuel supplier, told the Thompson Reuters Foundation.
One of the lessons learned, she said, is that making the biofuel locally is key.
“When there’s no local production capacity, the feedstock must be shipped out of the country and shipped back after refining. This makes the sustainable aviation fuel much more expensive,” Ms. Laroy said.
The Waste to Wing project, with $1.4 million in funding from the European Union's SWITCH Africa Green Programme, aims to solve that problem, cut costs, and protect agricultural production and forests by using waste to create fuel.
The effort, a partnership by South African social enterprise Fetola, WWF, and SkyNRG, aims to create a clean jet fuel supply in South Africa, a country with a long history of developing and using alternative fuels.
As part of the project, 25 small businesses will collect and supply the plant matter needed to make the biofuel – an effort to create jobs in a country with one of the world's biggest unemployment rates.
Amanda Dinan, Fetola's project manager, said the businesses could use invasive plants, collected in environmental restoration projects and currently simply stored or abandoned, as the raw material for jet fuel.
Such stores of dried plants today can present a wildfire risk in a country suffering drought, so are often purposely burned to avoid that risk, she said.
But the waste could provide jobs "in its harvesting, collection, pre-treatment, and transport,” Ms. Dinan told the Thompson Reuters Foundation.
She and energy economics and policy specialist Ms. Bole-Rentel said no biomass will be produced for being converted to fuel.
“As the name suggests, the Waste to Wing project will focus on waste biomass," including leftovers from food and livestock feed production, paper making, and furniture production, Bole-Rentel said.
At the moment, most of the agricultural waste produced in the country is burned, she said.
In some areas, harvested invasive plants already are being used to produce charcoal or fibrous products such as coffins, but most of the waste is unused, she said, and only that unused supply will be diverted to the jet fuel project.
Bole-Rentel said the project was designed to stand up to worsening drought linked to climate change in southern Africa, and ensure food-producing land isn't used to make fuel instead.
South Africa still has large swathes of invasive plants to clear, and the weeds are spreading faster than they can be cut back, Dinan said, which means the jet fuel project could both aid that effort and is unlikely to run out of stock to make fuel.
Sampson Mamphweli, director of the Centre for Renewable and Sustainable Energy Studies at Stellenbosch University, agreed the country has plenty of organic waste.
"Whether they use organic waste, or they plant the biomass for energy, whichever way the project is worth investigating,” he said.
One huge challenge with such projects is the cost of transporting plant waste, so material would need to be sourced as close as possible to where jet biofuel is produced, Mr. Mamphweli said.
And “the cost of the actual biomass material is also a big factor," he said. Often, a once useless and free material becomes valuable when there is a use for it, he said.
Bole-Rentel said it was too soon to get any real picture of how much of South Africa's aviation fuel needs might be met by the waste-to-fuel project.
But "our previous research into biomass availability suggests that, technically, there could be enough biomass to meet 100 percent of our aviation fuel demand," she said.
But under current technology the biofuel would need to be blended with conventional jet fuel, meaning the waste technology could supply at best half of the country's needs, she said.
This story was reported by the Thomson Reuters Foundation.