Award-winning compostable ‘plastic’ bag launched

A new, affordable design replaces plastic with biodegradable fibres from waste paper and food.

Plastic bags get such a bad rap that you begin to wonder if they’re just the sustainability scapegoat, or if they actually deserve it. But with between 500 billion and a trillion consumed worldwide every year (around 100 per person), it’s fair to say that they do. Local initiatives to ban them (from Modbury in Devon, to San Francisco) are all very well, but behaviour is a slow-moving bus…

So the commercial development of an affordable, compostable replacement is good news. Start-up Cyclewood Solutions has licensed a technology developed by the University of Minnesota for a bag made from lignin. This is one of the most abundant polymers on the planet, naturally occurring in wood and plant stems. Millions of tonnes of it are discarded each year as a waste by-product of the food and paper industries.

“By using a waste stream, we can offer retailers a product that is comparable in price to conventional plastic products”, says Nhiem Cao, President and CEO of Cyclewood. The Xylobag, he claims, biodegrades in 150 days, following exposure to bacteria or fungus. It costs $0.015/bag, only slightly more than the average cost to a retailer of a standard bag made from polyethylene ($0.012).

Ramani Narayan, professor in chemical engineering and materials science at Michigan State University, says Cyclewood will face competition from other biodegradable bags already on the market. But these competitors don’t do quite the same job: they may release carbon and methane as they decompose, and can’t be thrown onto the compost heap as a useful resource. 

The new business was awarded a $10,000 prize in the Austin Technology Incubator regional Cleantech Open, which aims to recognise big business ideas that tackle “urgent energy, environmental and economic challenges”. – Nick Huber