this episode is sponsored by LastPass
humanity hasn't exactly done a great job when it comes to energy production I
mean don't get me wrong we're good at producing enough electricity to meet our
needs but it's come at the cost of releasing billions of tons of carbon
dioxide into the atmosphere and wreaking some pretty serious havoc on the climate
not to mention that the planet has a fairly limited supply of the main fuels
we use like oil and gas one way of reducing our reliance on them is with
nuclear fusion releasing energy by fusing atoms together the idea is so
much potential that researchers have been working on it for at least half a
century the problem is we're still a long way off
there's a running joke among physicists that fusion power is always 30 years
away but that doesn't mean we've given up there are experiments in the works
right now that are way more advanced than anything we've ever done and if all
goes well the future of energy production might involve much more power
and way less pollution than we could ever hope for with the technology we
have today we already have a few options when it comes to clean energy but they
all have their drawbacks things like solar and wind power are great because
they're renewable and don't cause climate change but they can hurt the
ecosystems around them and usually aren't very efficient they're also
inconsistent and we're still trying to find practical ways to store enough
power to compensate for times when say it's super cloudy for a week and there's
also nuclear fission which releases energy from splitting atoms usually
uranium or other heavy elements like plutonium specifically fission involves
splitting the center of the atom it's nucleus which is where the term
nuclear energy comes from but supplies of the heavy elements we need for this
could run out pretty easily too even worse fission generates tons of
radioactive waste from the leftover fuel we don't want that hanging around on the
planet for a couple thousand years polluting the environment and
threatening lives nuclear fusion on the other hand avoids
all of these problems it barely releases any co2 doesn't produce radioactive
fuels as waste and unlike renewable sources such as
solar and wind we could control how much power we generate to keep things in line
with demand if we could figure out how to use it effectively that is to
generate power all we have to do is get nuclei defuse and capture the energy
from the particles that are released in the process unfortunately getting them
to fuse involves an enormous amount of pressure and heat just temperature-wise
we're talking close to a hundred and fifty million degrees Celsius
least in the conditions here on earth sure we can get atoms to fuse in h-bombs
thermonuclear weapons use a fission explosion to set off a fusion explosion
but while that's a super effective way to blow something up it isn't really a
safe useful or efficient way of generating energy the problem is it's
hard to get fusion going without using the energy from a massive explosion to
do it a few different chemical elements can undergo fusion on earth but
scientists have pinned most of their hopes on combining deuterium and tritium
those are just ordinary hydrogen nuclei with one or two extra neutrons tacked on
respectively the two nuclei are able to fuse into helium releasing a neutron
with a bunch of energy in the process even better that helium nucleus can give
up some of its energy to nearby electrons which in turn can heat up more
deuterium and tritium causing even more fusion to happen that process is called
alpha heating and without it a fusion reactor isn't likely to produce enough
energy it's sort of like trying to start a fire in a cold environment unless you
supply enough heat in the first place your fuel will just lose energy to the
surrounding cold air instead of igniting and starting a self-sustaining burn when
the conditions are just right for fusion to deliver more energy than the heat
energy required to get it going it's called ignition in thermonuclear weapons
that's what the fission explosion is full in a fusion reactor it means you
need to be able to hit some seriously high temperatures and there are two
major approaches to this ICF and mcf ICF or inertial confinement fusion involves
filling a tiny pellet with deuterium and tritium and getting them to fuse by
imploding the pellets with high-powered laser beams the National Ignition
facility in California has aimed to do exactly that firing the world's most
powerful laser split into a hundred and ninety-two beams onto fuel pellets the
size of a pinhead when the pellet implodes the fuel inside undergoes
fusion and releases energetic neutrons but for full ignition the pellet would
have to collapse perfectly inward to transfer all of the energy from the
lasers into the fuel and start a self-sustaining reaction focusing the
lasers onto a target that small is tricky enough but the real difficulty is
making the pellet collapse in on itself in just the right way it has to be made
as perfectly spherical as possible and pressure has to be applied equally in
all directions so far the most successful strategy has been to put the
pellet in a pencil eraser sized gold cannister with the lasers firing into
that instead when the gold heats up it emits x-rays on the inside generating a
more symmetric pressure on Pellatt so it collapses in on itself and
if' has been able to generate small amounts of energy from this type of
fusion in 2013 the lab actually achieved a gain in energy for the first time
getting more energy from the neutrons exploding out of the pellet than the
energy delivered to it from the x-rays in the canister unfortunately it wasn't
more energy than the total amount going into the system from the lasers and
ultimately that's the benchmark for turning fusion into a practical way of
generating power getting more energy out than the total we put in to get it going
one of the biggest problems is that when the outside of the pellet is heated to
extreme temperatures it tends to burst off in an unstable way creating an
uneven pressure on the target despite those setbacks between 2010 and 2012 NIF
went from needing to produce thousands of times more energy to get to ignition
to only needing tens of times more energy that a hundred fold difference
came from more effective pellet designs but keeping up the pace of improvement
has hit a wall recently the other approach is mcf or magnetic confinement
fusion which works in a totally different way it's based on a type of
reactor called a tokamak a doughnut shaped chamber that produces incredibly
strong magnetic fields inside the reactor there's deuterium and tritium in
the form of plasma or charged gas basically a bunch of nuclei and
electrons just floating around then you blast the plasma with microwaves or a
beam of neutrons heating it up and ultimately making it undergo fusion
better still if you line the outside of the reactor with lithium neutrons
released in the fusion process will generate tritium introducing more fuel
into the reactor a lot of the excitement surrounding fusion has focused on the
MCF approach but the problem is that containing a plasma with magnetic fields
is like trying to herd trillions of uncooperative cats all at once they just
keep trying to escape the magnetic fields and the way they interact with
the plasma leads to what's called turbulent behavior flowing in a way
that's twisted and complex on every scale you look at it turbulent fluids
are tricky to make certain kinds of predictions about even with computers
and I can get even harder as you heat up the plasma to the kinds of temperatures
needed for ignition so designing and maintaining magnetic fields that can
keep the fuel mixture contained it becomes more of a challenge like ICF mcf
experiments have managed to achieve fusion but only a little the record for
energy gained that is the amount of energy that came out compared to the
energy used to heat up the plasma in the first place is still held by an
experiment in 1997 using the jet reactor in England on that
occasion it produced 67% of the energy that was initially put in the reason we
haven't been able to improve on it much in the past couple decades is that jet
can only do so many fusion experiments with deuterium and tritium the neutrons
released in those kinds of experiments tend to make the surrounding material
radioactive so to keep the total radioactivity levels low experiments
tend to only happen every few years plus tritium isn't easy to come by and jet
doesn't have a way of producing lots of it on-site so they have to be sparing
with how much they use but the record could be broken in 2019 when jet is
scheduled to run a new batch of fusion experiments with deuterium and tritium
it's also managed to achieve some seriously high temperatures over 200
million degrees although not for very long
as recently as 2018 though there were a couple promising results from some
smaller mcf experiments for example a Chinese experiment called East managed
to maintain a temperature of a hundred million degrees in its reactor and even
sustained fusion for ten whole seconds one of the biggest developments in 2018
wasn't an experimental result it was a letter signed by experts from the US
National Academies for Sciences engineering and medicine in it they
declared their support for an experiment in southern France that isn't even done
being built yet it's called ITER and when it's done it will be the world's
largest tokamak reactor 35 countries have come together to build it it's a
long road but by 2035 eiders should be ready to start deuterium-tritium fusion
experiments and because it's so much larger than jet the world's current
biggest mcf reactor it should be able to hold a lot more plasma in its magnetic
field the larger volume means the plasma interacts with itself more than in a
reactor like jet this keeps more of the heat trapped in the plasma and makes it
likely or for ignition to happen the goal is to generate 10 times as much
energy from fusion than the amount of energy supplied to it that would be the
first viable demonstration of fusion as a power source but increasing the size
of the experiment brings along a whole set of extra challenges large magnets
require lots of energy and even more work to operate the magnetic fields they
generate and contain such a large amount of plasma in it even if it works there
are still some challenges to tackle like dealing with the radioactive material
that gets generated in a reactor from all the parts being bombarded by
neutrons it's not radioactive fuel waste like an efficient reactor so it's not as
bad but it is still some radioactive stuff that will have to eventually
disposal plus extracting energy from the neutrons generated by
fusion wouldn't be quite as straightforward as it is in conventional
power plant the walls of the reactor are what captured the neutrons and heat up
in a power plant the walls would then heat water surrounding the reactor into
steam to drive turbines but being bombarded by all those neutrons can make
the walls brittle and radioactive over time to handle that damage for a
long-term reactor scientists need to design walls that are more resilient but
still able to efficiently transfer heat out of the reactor
although ITER won't be able to deliver power researchers hope that if it's
successful those issues could be worked out in an even bigger test reactor
called demo in the meantime we'll keep working on all those other options for
cleaner energy like solar power and nuclear fission a lot of work is being
done to make those technologies safer and more environmentally friendly too as
for fusion for now the old joke holds true fusion power is still at least 30
years away but maybe it won't be for long thanks again to LastPass for
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