it's 3:00 in the afternoon on a
Wednesday when you hit the afternoon
slump you're tired and probably not just
because you were up late binge watching
season four of Buffy the Vampire Slayer
your body is low on energy so you grab
an apple for a quick snack food is
energy after all that's why we eat it
but instead of throwing away that core
when you're done try putting it in the
garbage disposal there's a lot of energy
left in there in this way it might be
converted into something useful because
when food waste ends up in landfills it
actually creates a lot of problems it
takes time for that uneaten apple core
to decompose and meanwhile bacteria are
turning it into methane that's an issue
because methane is a greenhouse gas and
it's actually significantly better at
trapping heat than carbon dioxide which
got on a scientist thinking what if you
could figure out a way to control how
the food waste decomposes and in the
process produce energy we can actually
use and add the potential to help the
planet and make lots of money so win-win
really but it wasn't gonna be simple the
first challenge was just getting the
food waste itself recycling programs are
pretty successful but it's still hard to
get people to agree to scrape the food
out of the takeout container before they
throw it in the trash or get restaurants
to separate food scraps cities are
slowly starting to get on board
mandating that commercial establishments
like restaurants send no more than a
certain percentage of their waste to
landfills but even after they've
separated out the food waste there's
still the matter of getting it somewhere
to be processed not to mention figuring
out how to process it at first cities
decided to take advantage of existing
sewage treatment systems we've talked
here on scishow about where the stuff in
your toilet and sink goes after you
flush and eventually part of it ends up
in an anaerobic digester basically just
a giant tank full of sludge and some
specially selected microorganisms but
very little oxygen bacteria would
normally digest that sludge using a
reaction that has carbon dioxide as one
of the products but Megan carbon dioxide
requires oxygen and when there isn't
enough around they have to do the best
they can with what they have so they end
up producing methane instead and that's
much more useful to us because the
treatment plant can harness that methane
and turn it into a usable fuel when your
apple core goes down the drain it lands
in the sewage system it eventually ends
up in the sludge where bacteria can use
it to produce even more methane so at
first cities simply added their
food waste to the mix once they'd
figured out that this was an effective
way to turn food waste into methane
companies started building treatment
plants specifically designed to handle
food waste many of these plants have
deals with local utility companies that
are able to sell the extra fuel in the
form of heat or electricity or just
compressed natural gas sell enough and
they turn a profit but that thing still
isn't an ideal fuel to move it around or
burn it you have to compress it first
which takes extra energy and makes the
fuel less efficient and while methane is
easy to use in power plants once they
get it it's more difficult to use
compressed natural gas to save power a
car that's why these days many companies
are looking to turn food waste into an
even more useful form of energy ethanol
the stuff that is in your tequila ethyl
alcohol there are plenty of industrial
plants that produce ethanol from things
like corn and they've been doing it for
decades one of the more common
techniques uses enzymes to convert
cellulose into sugar and that allows
yeast to turn that sugar into ethanol
and carbon dioxide since those plants
use very specific raw materials or
feedstock the chemical reactions are
easier to control producing ethanol from
an unpredictable mixture like food waste
is more complicated but there are
already bio refineries that use other
kinds of ways to produce ethanol like
one in Edmonton Alberta that started
operations last year that plant takes
what's known as municipal solid waste
anything that can't be recycled or
composted then it sorts that waste
separating out stuff that can be used as
feedstock for that plant like non
recyclable plastics and soiled cardboard
the feedstock is processed using
gasification where high temperatures hot
sand steam and oxygen are used to
convert it into a mixture of carbon
monoxide and hydrogen called syngas
using catalysts to help spur the
reactions along the syngas is turned
into chemicals like methanol and ethanol
companies haven't yet applied the
technology to food waste on an
industrial scale but they're working on
it as we develop more ways to use
renewable fuels like methane and ethanol
scientists and engineers all over the
world are working to take advantage of
untapped energy resources like food
waste among them our engineers at the
Emerson Electric Company which sponsored
this episode of scishow thanks to them
for their support and thank you for
watching this scishow dose if you want
to keep getting smarter with us you can
go to youtube.com/scishow and subscribe
you