I was recently on a mountain bike trip in Italy. And while I
was riding one day, I thought there are a lot of similarities
between mountain biking and energy storage. "How?" you might
ask? In this video, I'm going to show you how my body takes
energy stored in food and converts it to mechanical energy
similar to how a fossil fuel power plant works. Then I'm
going to show you how pedaling up a hill or using an electric
motor on an e-bike to climb a hill stores energy through
gravitational potential in a similar way to how
hydroelectricity does and then I'm going to talk about other
emerging energy storage technologies and how they fit
in.
So this is a typical day in the life of a mountain biker, you
eat a bunch of breakfast, you pedal and push your bike up the
hill for a while. And then the fun part, you descend. And since
this ride was in Italy, there were a few stops for pastries
along the way. So how does this relate to energy storage? The
breakfast part: energy is stored as chemical potential energy in
the food. If it's a plant based food or something that eats
plants, then the energy originally came from the sun.
When I eat my digestion system creates some chemical reactions
which release energy that I can use to move my legs and pedal my
bike up a hill. Similarly, a coal mine or an oil or gas
reservoir contains chemical potential energy that was
created by plants who got their energy from the sun millions of
years ago. And then instead of a digestive system, it's a power
plant that will burn the fuel to create the chemical reactions
that transform the energy to heat. The heat is used to create
steam, which turns a turbine that's connected to a generator,
which then converts it to electricity. Fossil fuels don't
allow us to control the energy storage at all. It happened
millions of years ago. And we can't create more fossil fuels
if we have surplus energy in some other form. Plus, when we
release its stored energy, we also release greenhouse gases
that would have stayed locked underground for millions more
years. And now that we know that this is causing problems, we
don't want to do that anymore.
There are other ways to store chemical potential energy
though, that we can control. The most common way is in batteries.
We're all used to using batteries to store energy to
power our devices. We've been using them for years and each
development in battery technology has allowed whole new
classes of technology to develop. They started with wet
cells in the early 19th century to power electrical telegraphs,
moved on to try cells towards the end of the century, which
allowed portable electrical devices to develop. Then came
rechargeable batteries like lead acid still used in cars. And
most recently, the focus has been on new metals like lithium
to reduce the weight of batteries. Lithium ion battery
developments over the past couple of decades have seen
mobile phone sizes shrink and increased the range of battery
electric cars. And now they're also starting to be used in the
electricity grid like the Hornsdale battery in South
Australia. And you may have noticed that batteries are also
being used by cyclists these days, there are more and more
e-bikes around. As batteries get lighter and cheaper people are
choosing to get the energy they need to get up a hill from
electricity stored as chemical energy in a battery. And my
method of eating food to get the energy to pedal up hills is
starting to look a little bit old school.
So batteries are one way we can store electricity to use later.
It's a big topic and I'm going to be returning to it in future
videos to look at specific applications. And alternative
way to store surplus electricity in the form of chemical
potential energy is hydrogen. If you use electricity to split
water into pure hydrogen and oxygen in a process called
electrolysis. You can get the energy stored in hydrogen back
again either by burning it similar to how natural gas is
burned or via a fuel cell. In either case, hydrogen reacts
with oxygen which transforms the chemical potential energy to
electricity either directly in the case of a fuel cell or via
heat and a turbine and a generator in the case of a
natural gas style power plant. In either case, the byproduct is
water. Now this sounds absolutely perfect having only
water as a byproduct, but there are some downsides to hydrogen
too and some challenges that need to be overcome. Again, that
is a huge topic. And so I'll be exploring the opportunities and
challenges associated with hydrogen applications in depth
in an upcoming video series.
So like I said, my energy storage method that I've chosen
for this bike tour is starting to feel a little bit old
fashioned, I'm eating food that I can essentially burn for
energy just like a 19th century coal powerplant. As I pedal up
the hill, I'm converting the energy again, this time to
gravitational potential energy. And then on the descent, I
convert it to kinetic energy, as my altitude decreases and my
speed increases. Now at least this part of the energy
transformation is starting to feel a bit more modern. Just
like I'm doing here, pumped hydro gains gravitational
potential energy as water is pumped uphill, and then
transformed into kinetic energy when it descends. But of course,
using gravity to store energy isn't new. Humans have been
taking advantage of this for thousands of years starting with
waterwheels turned by the flow of water running downhill
through to hydroelectric dams located high in the mountains
that control when to allow the water to flow downhill and turn
a generator. But widespread pumped storage is pretty new, or
at least it's experiencing major growth right now. In pumped
storage, water is allowed to flow downhill to generate
electricity at times when it's expensive or in short supply,
and then it's pumped back uphill to the reservoir when
electricity is cheap or oversupplied. Traditional
hydroelectricity without pumping capability allows us only to
store as much energy as falls as rain. If there's a drought, the
water could run out. And where I'm from in Australia, this does
happen pretty regularly. Pumped hydro allows a lot more control
to balance out peaks as well as troughs in the electricity
supply. But you can't put pumped hydro just anywhere, you need to
have a suitable site for it, which means big elevation
difference, and you probably want a water source. And
hopefully you're going to stay away from damming beautiful and
ecologically important valleys. So there are a lot of places on
earth that need energy storage but don't have a suitable site
for pumped hydro. There are alternative ways to use gravity
storage like hauling massive blocks up and generating
electricity when they're allowed to fall again, there are several
variations of this concept under development currently, including
one company from very close to here who use cranes to stack
concrete blocks into a tower, and then they generate
electricity by lowering them again.
I think the topic of energy storage is interesting because
on the one hand, it's a very modern technology. But on the
other hand, very ancient. We've really only needed it in a
widespread way now that we'r starting to add sign
ficant amounts of variable rene able energy to our elec
ricity grid. And I think that that's why we've seen such a re
ent explosion in different kind of energy storage tech
ology development. But on the ther hand, as I've shown here
the basic principles of ener y storage and the different kind
of physics and chemistry that we can exploit to get ener
y when and how we need it, thos are not modern at all. Natu
e has been storing the sun' energy as chemical pote
tial energy in plants, anima s and fossil fuels for milli
ns of years, and humans have een exploiting gravi
ational potential energy as a eans to create mechanical energ
for thousands of years. But w at is new is that we have gaine
the capability to take large amounts of excess elect
icity at times of overs pply and store it for futur
use. This is a crucial part f our green energy trans
tion as it frees us from needi g piles of coal or oil or gas r
servoirs as the only means of en rgy storage. The better our e
ergy storage options get, the m re easily we'll be able to incor
orate large amounts of varia le renewable energy into our e
ergy mix.
Yeah, of course, I've only barely touched on the basics of
energy storage in this video. It's a really important but also
really complex topic and like, like everything that I talked
about, like every kind of technology development, there
are advantages and disadvantages for every type of energy
storage. And as always, there are complex trade offs to be
made. And I'm going to be making more videos delving deeper into
these topics in the future. So if you have a favorite emerging
energy storage technology, tell me in the comments so I can make
sure I cover it. And please remember to like and subscribe
if you want to see more videos like this.
In a future video, I'm going to be taking this bike ride example
a little bit further and this time doing some calculations to
allow a comparison of some specific details. I'll be
looking at the round trip efficiency and energy density of
some different energy storage technologies. And I had the
thought that since e-bikes, are becoming so popular and hydrogen
is becoming so popular... Why haven't we seen a hydrogen fuel
cell a bike yet? So I thought it would be cool to do some
preliminary design for a bike like that. So if that sounds
interesting to you, then keep an eye out for that video in the
future. Thanks for watching, and I'll see you next time.