Collaboration was part of the package from the start for Canadian PHA start-up Genecis. By piggybacking off the infrastructure provided by existing biogas plants, the company has a head start over fellow PHA producers in terms of feedstock sourcing and scaling. Using food waste yields a competitive advantage for Genecis, while enabling the production of both biogas and PHA. It’s an impressive demonstration of the power of circularity.
It's also a story about how one PHA producer decided it is going to do things differently than the rest.
Food waste is an anathema to Luna Yu, the founder and CEO at Genecis Bioindustries, a start-up company based in Toronto, Canada. The way it is disposed of today – mainly in landfills – creates problems in terms of both available space and greenhouse gas emissions. Increasingly, organic waste diversion is a growing priority at landfills.
Having previously gained experience in the biogas industry, Yu saw an opportunity. She was told that, without subsidies, biogas plants were inherently unprofitable, despite being, as she said ‘one of the best ways to repurpose food wastes and divert them away from landfills and an offset carbon emissions’. But without subsidies, she was told, a biogas plant was never going to be profitable.
“I thought, well, why not take those really valuable fatty acids that you get from the process and instead of making methane out of them, which is a super low value product, what if you could create much more efficient bacteria, to make a much higher value product instead?” she said.
That idea grew into what is today a full-fledged biotech company that is fast working to progress from pilot scale towards demonstration and commercial scale production of PHAs, with plans in the longer term to explore the production of chemicals and materials using the volatile fatty acids in the platform thus far developed.
Plastic from microbes
In 2017, Yu and a group of like-minded scientists started on a quest to find, identify and create the microorganisms suitable for the process she envisioned; specifically, bacteria able to convert short-chain fatty acids from food waste into PHAs.
The PHA family is a big one. Scientists have found more than 150 PHAs with different polymer structures. The kind of bacteria and the substrate used— sugars, starches, glycerin, triglycerides, methane—determines the type of PHA produced. At Genecis, drawing on the diverse backgrounds of the scientists and engineers at work there, a combination of artificial intelligence and genetic engineering was used ultimately to develop microorganisms that could handle the task.
Deposited as water-insoluble granules inside the cells, PHAs are composed of hydroxy fatty acids and are produced by microbes as a source of metabolic energy as well as a carbon store. Cultivated in fermentation tanks, the bacteria, once mature, undergo mechanical or chemical lysis, after which the PHA is separated from the cell debris in a washing step to obtain the pure polymer. This is then compressed into pellets, which can be further blended into compounds or processed into end products.
PHAs are biopolyesters, and as such they are not only 100 percent biobased, but they also biodegrade in soil, freshwater, and marine environments, and are both industrial- and home-compostable. While that alone makes them an interesting class of materials, they can also offer physical properties and functionalities that are comparable to polyethylene and polypropylene, and even PET, and are suitable for use in a wide range of applications, such as cutlery, cups, films, bottles, and other packaging.
Yet despite these highly attractive characteristics, PHAs have been a research target for many decades, without ever having become more than an expensive niche product. It is not hard to see the reason for this: the traditional methods for PHAs production are extremely expensive.
Most other commercial PHA manufacturers rely on high-cost substrates: pure sugars, fats, and animal or vegetable proteins. “Expensive and hard to scale,” said Yu. She added that the cost of the carbon source can contribute some 40–60 percent of the overall cost of PHA production. For production to become cost-effective, an abundant, inexpensive source of carbon must be found.
“Which is exactly what we have done,” explained Yu. “Instead of buying sugars, we use organic food waste, which literally costs nothing, while our bacteria allow us to produce PHAs at the same efficiency as sugar feedstock. So, our feedstock is more challenging to work with and to control, unlike sugars, which have a very consistent quality but by using a zero-cost feedstock, we’ve eliminated all those costs at a single stroke.”
Plus, as she pointed out, using waste not only means there is no competition with the human food supply, but the PHAs Genecis produces are also more carbon negative than those of competitors. By diverting food waste away from landfills where it degrades and produces the greenhouse gas methane, the company can offset 0.8 tonnes of carbon emissions per tonne of food waste processed.
“Food waste on its own is actually the third largest methane emitter right after fossil fuels and livestock or agriculture,” said Yu. “It’s exciting to be able to offer a solution that tackles the problem of food waste, finite resources and pollution, all at the same time.”