Scientists are trialling out new techniques for converting food waste into graphene and hydrogen. Scientists at the City University of Hong Kong can turn coffee grounds
and stale bakery goods into a sugary solution that can be applied to
manufacture plastic.
Blended cocoa beans, rice, fruit skins, leeks and asparagus sounds
like it should be a recipe for a disastrous smoothie. But these are just
some of the wasted foodstuffs that are being treated and converted into
materials, with environmental benefits.
Scientists at the City University of Hong Kong have found that they can turn coffee grounds and stale bakery goods – collected from a local Starbucks – into a sugary solution that can be used to manufacture plastic.
The food waste was mixed with bacteria and fermented to produce
succinic acid, a substance usually made from petrochemicals, that can be
found in a range of fibres, fabrics and plastics.
Meanwhile, engineers at the Colorado School of Mines have discovered a way to turn banana peels, eggshells and rice husks into glass.
By blending, drying and pounding it into a fine powder, and with a
little help from the magic of science, they found the mixture could
provide some of the metal oxides required in the composition of glass.
Ivan Cornejo, a professor at the university, told the Denver Post at the time that such an innovation could reduce the need to mine for silica, one of glass’s primary components.
Food into graphene
Now, a new EU project, PlasCarb,
is researching a way to fashion food waste into graphene. It’s
perfectly timed, given the recent buzz surrounding the material and its
potential to revolutionise the green industry. The material, discovered in 2004, is so super, Bill Gates is even investing in it to develop an ultra safe condom.
The project uses a process known as anaerobic digestion (AD), where
waste is converted into biogas. Finding a new lease of life for food
waste using AD isn’t anything out of the ordinary. Businesses have been
using the process to make energy for some time. Most notably, early last
year, Harvest Power, a Brooklyn-based waste treatment plant, built a
digester to deal with waste coming from Disney World. More recently, Sainsbury’s partnered with recycling specialists Biffa to launch their first shop powered by food waste collected from the chain’s stores. But PlasCarb takes the process one ambitious step further.
“Together with an innovative low-energy plasma reactor we convert the
biogas from AD, which is mainly methane and carbon dioxide, to
graphitic carbon [from which comes graphene] and renewable hydrogen,”
explains project manager Neville Slack, from the Centre for Process Innovation.
Beyond the science and technicalities of the process, PlasCarb offers
a possible dual advantage over how traditional materials and gases are
produced: a happier environment and a commercial use for food waste from
a range of industries including retail and hospitality.
“The obvious benefit is taking waste destined for landfills and
transforming it into raw materials in a sustainable way,” adds Slack.
“Graphene is the latest wonder material. Hydrogen has also been
identified as a future transport fuel for a low carbon economy.”
Food mountains
According to the PlasCarb, 95% of hydrogen currently comes from
fossil fuels. And some bioplastics produced from crops such as corn are
beginning to be deemed unsustainable. The belief is that there won’t be
an endless supply of crops, but whether we like it or not, there will
probably always be a high volume of discarded food. Growing materials
from waste streams could also reduce concerns over how corn-based
biopolymers may impact on crop prices, land availability and food
shortages.
Graphene and hydrogen from surplus food are desirable alternatives,
but despite the exciting prospects they offer, Slack and his team aren’t
getting ahead of themselves. There is still a question of scalability
and how both small and large businesses could access the technology to
deal with their waste. He says the project is still in its infancy –
it’s in its second year of its three-year duration – and that the
economics of it all need to be ascertained. A pilot trial lasting at
least a month will see 150 tonnes of food transformed into 25,000 cubic
metres of biogas and then on into the graphitic carbon and renewable
hydrogen. The results of this will give the team some indication about
future market interest and uptake.
There’s no doubt that, if scaled up successfully, PlasCarb could play
a key role in helping prolong food’s life cycle. But Slack suggests
that it doesn’t take away from the fact that, in an ideal world, there
wouldn’t be any waste at all. Even though the EU has steps in place to
improve the situation (including a target to reduce waste by about 30%),
estimates indicate
that more than 100m tonnes of food is thrown away annually across the
union, and this could rise to 126m by 2020 if not enough action is
taken.
