From leather made from unwanted apples to spandex coaxed from the byproducts of corn production, agricultural leftovers are being transformed in some surprising ways. Farm byproducts once deemed waste are increasingly seen as a resource, and cutting-edge science is driving this innovation.
“Since agriculture relies on natural cycles for its inputs, there is tremendous potential in applying circular bio-economy techniques to the sector,” says Professor Kechun Zhang from the University of Minnesota. He leads a team that has designed a new biosynthetic pathway to turn agricultural waste – the likes of orange peel and maize leaves and stalks – into useful products such as chicken feed.
Most recently, they developed a pathway to convert three of the sugars most common in biomass waste into a useful raw material. The compound 1.4-Butanediol (BDO) and its derivatives are used to produce spandex among other commercial products. In another corner of the lab, the team is working on converting sugars such as glucose into biodegradable polymers that they hope could eventually replace those derived from petrochemicals.
Rooting around in search of the redeeming qualities of farm waste is not everybody’s idea of an enjoyable day’s work. So why pursue this?
“There is an urgent need to move from a fossil-based economy to a bio-economy,” says Zhang. “Lignocellulosic biomass [plant dry matter] is the most abundant organic matter in nature with an annual output of 2x1011 [200bn] metric tons. Thus, it is a very promising alternative to fossil-based feedstocks.”
And he isn’t alone. Italian engineer Alberto Volcan is investigating the creation of leather from waste apples. Wastage in the apple industry is thought to be as high as 40%. Mixing apples, water, apple flour and natural glue creates a gloop capable of producing leather thick enough to be commercially useful.
Meanwhile, Somerset’s Wyke Farms uses cow manure to power the farm’s biogas cheese plant. When it opened in 2013, the plant was only the latest attempt to keep Wyke’s farmland fruitful and healthy by enlisting circular, sustainable techniques.
“We use the ‘muck’ of the land to grow the grass and feed the cows, which in turn give milk and produce the muck to feed the land again, explains managing director Rich Clothier. “With the biogas plant, we are not only preserving the cycle but adding in an additional critical phase to produce green power.”
A shift in mindset meant that manure has become a precious fuel and the farm became the first national cheddar brand to be 100% self-sufficient in green energy generated from solar and biogas. The plant converts 75,000 tonnes of biodegradable farm and dairy waste into energy each year, with two combined heat and power generators being used to power the dairy with biogas. Roofs on farm outbuildings hold solar arrays while a £1.3m water recovery plant enables the recovery of up to 90% of water on the farm.
“I’m massively excited by the untapped potential on UK farms,” says Clothier. “There is a mine of highly calorific organic waste that just gets land spread, wasting its energy value. If we could get all of this organic waste into anaerobic digestion plants then farms around the UK could be the key to energy generation going forward.”
But how receptive is the industry to these sorts of ideas?
“Uptake of renewables in the farming business has been slow,” admits Clothier, citing the main barriers to the adoption of more circular solutions as finance and mindset. “But we are seeing change. Some businesses have found that, like we did, when you start to think sustainably, it can take hold and change the business and the people forever.”
The EU is taking an interest in integrating the circular economy and the bio-economy to create a circular bio-economy within agriculture and forestry. What could this look like?
“In practice there will be myriad circular bio-economies operating on a variety of scales and in different contexts,” says Dr. Ben Allen, senior policy analyst in the agriculture and land management programme at the Institute for European Environmental Policy.
“The circular bio-economy is not an entirely new concept in agriculture. For example people have been using livestock manure to fertilise land to grow crops to feed animals for centuries. Yet as our knowledge increases and our technological capacity grows, we have increasing potential to use a whole range of waste streams and bioresources to produce new and novel products.”
However, for Allen, this is not all about the new. Traditional products such as food and timber remain important elements of any developing bio-economy initiative.
“What I find most exciting is that the idea is gaining traction, not just in response to an issue that needs to be tackled, which of course it is, but because it is a positive and beneficial thing to do.”
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