Do you, like many Americans, enjoy the tangy taste and thick creaminess of Greek yogurt? Well, one day your yogurt could help fuel airplanes.
Researchers at Cornell University and the University of Tübingen in Germany have developed a method of turning yogurt whey, the liquid left behind after straining out the milk proteins, into bio-oil. This bio-oil could then potentially be processed into biofuel for vehicles, including planes.
Lars Angenent, the microbiologist and environmental engineer who led the research, says he watched the Greek yogurt craze explode in upstate New York while he was working at Cornell. Local Greek yogurt producers used fleets of trucks to haul away liquid whey – for every kilogram of yogurt, there’s two to three kilograms of whey left behind, and America produces more than 770,000 metric tons of Greek yogurt annually.
“If we treat the waste on site – that means at the yogurt plant – less trucking is needed, which reduces the carbon footprint,” Angenent says.
His lab had discovered how to convert lactic acid into bio-oil, and Angenent knew whey would be a good source for lactic acid. They tested the process and found that it did indeed work the way they’d hoped. The team recently published their research in the journal Joule.
The bio-oil produced from whey could also potentially be used as animal feed. Its natural antimicrobial capabilities could help replace antibiotics, which are commonly used to treat farm animals but bring risks of antibiotic resistance.
“[If] the bio-oil can be fed to the cows and acts as an antimicrobial, we would close the circle, and the Greek yogurt industry could become more sustainable,” says Angenent.
Angenent has created a company to explore the commercial potential of this technology, and hopes to see the bio-oil in use by 2020. He and his team are also investigating the biofuel potential of other waste liquids.
Joanne Ivancic, executive director of Advanced Biofuels USA, a nonprofit dedicated to promoting biofuels, says Angenent’s research is promising, but that the future of any biofuel depends on numerous political and economic factors.
“The commercial potential of anything that’s going to take the place of petroleum or natural gas fuels depends on the price of oil and the price of natural gas,” Ivancic says. “They have to be competitive because supportive government policy is just not there.”
Since the early 2000s, conservationists and manufacturers alike have hoped that biofuels could help deal with both climate change and issues of fuel security. But growing crops like corn and soybeans to produce ethanol, the most common biofuel, has some major environmental and social downsides. These crops require massive amounts of fertile land, displacing crops that could be used for food and sucking up resources like fertilizer and water.
So researchers have been turning to other potential biofuel sources. Some are looking at plants such as hemp and switchgrass that are less resource-intensive than corn or soybeans. Sugar beets, termed “energy beets,” by their supporters, is another crop with fuel potential, and has the added benefit of remediating phosphorous in the soil, helping to keep nearby watersheds healthy. This past summer ExxonMobil announced the creation of a strain of genetically modified algae they say produces twice as much oil as regular algae. One company is beginning to process household garbage like eggshells and coffee grounds into jet fuel. In late 2016, Alaska Airlines powered a cross-country flight with a new biofuel produced by wood scraps. Like the yogurt whey, the wood has the benefit of being a waste product that would otherwise present a disposal challenge; many of the most promising potential biofuel materials are waste products or "co-products" of other processes.
Ivancic is optimistic that increasing cultural awareness about the perils of climate change will help make these kinds of biofuels economically feasible.
“In the 1970s we recognized the Clean Water Act and the Clean Air Act,” she says. “If we can tap into that same kind of concern for the environment then we may get the policies and the consumer demand that we need.”