Turning trash into treasure: biorefinery converts food waste to fuel

Food waste is bad news for the environment: not only do the resources used to grow, process, package, store and dispose of the food go to waste, but the waste also produces methane emissions. The UK Waste Resources and Action Programme (WRAP) estimates that for every tone of food wastage, the equivalent of 3.8 tonnes of CO₂ is generated.

In Australia, programs such as Foodwise and the NSW Government’s Love Food Hate Waste encourage consumers to minimise food waste, but retailers, food processors and primary producers are also responsible for significant amounts of food wastage.

While reducing food waste is one way to address the issue, there’s no denying that food waste will still continue to be produced. But rather than viewing food waste as, well, waste, what if we saw it as a resource?

City University of Hong Kong and Starbucks Hong Kong have collaborated to develop a ‘biorefinery’ intended to use food waste to produce plastics, laundry detergents and other everyday products.

In the same way that oil refineries convert petroleum into fuels and ingredients for consumer products, biorefineries convert plant-based material into a range of ingredients for biofuels and other products.

“We are developing a new kind of biorefinery, a food biorefinery, and this concept could become very important in the future, as the world strives for greater sustainability,” said Carol SK Lin, who led the university research team.

“Using corn and other food crops for bio-based fuels and other products may not be sustainable in the long run. Concerns exist that this approach may increase food prices and contribute to food shortages in some areas of the world. Using waste food as the raw material in a biorefinery certainly would be an attractive alternative.”

Starbucks Hong Kong produces nearly 5000 tonnes of used coffee grounds and waste bakery items each year, which is usually incinerated, composted or disposed of in landfill.

The biorefinery process involves blending the baked goods with a mixture of fungi, which excrete enzymes to break the products’ carbohydrates down into simple sugars. The blend goes into a fermenter where bacteria convert the sugars into succinic acid, which can be used to make laundry detergents, plastics and medicines.

Using the food waste to create succinic acid has a number of environmental benefits. By avoiding incineration, fewer pollutants enter the atmosphere, and the carbon dioxide produced during the biorefining process is re-used. The products made from succinic acid are sustainable alternatives to products made with non-renewable fossil fuels like petroleum.

The initial research was funded by donations raised by Starbucks Hong Kong, and Lin says the process could become commercially viable with additional funds from investors.

“In the meantime, our next step is to use funding we have from the Innovation and Technology Commission from the Government of the Hong Kong Special Administrative Region to scale up the process,” Lin said. “Also, other funding has been applied to test this idea in a pilot-scale plant in Germany.”

Lin’s research team reported on the project at the 244th National Meeting & Exposition of the American Chemical Society. The idea for the project was sparked by a discussion between not-for-profit organisation The Climate Group and Lin in 2011, when the group asked Lin whether her biorefinery technology could be applied to Starbucks Hong Kong’s food waste.