So, Lithium-ion batteries then. They're an astonishing piece of technology developed
back in the 80s by the legend that is John B Goodenough who, by the way,
is still working on new energy systems today at the age of 100!
Without the breakthrough that John and his colleagues achieved more than 40 years ago it's
probably fair to say that most of the technology we use today wouldn't exist. No MP3 players,
no smartphones, no life-saving medical implants or portable hospital devices, no electric vehicles
and no energy storage to complement intermittent grid scale renewable technologies like wind and
solar, without which the transition away from fossil fuels would be even more impossible than
it seems right now. So thank you Mr Goodenough for everything you've done for humanity. Happy belated
birthday greetings and congratulations on reaching the century mark. But fantastic as they are,
Lithium-ion batteries do have their drawbacks. Despite rapid cost reductions over the past decade
they're still relatively expensive, and although there are versions now that don't use any cobalt
or nickel, most do still contain those problematic commodities, along with lithium itself of course,
all of which are in short supply in today's troublesome global market. There's also the
problem of self-combustion, which while very rare is nevertheless a potential eventuality in
every single lithium-ion battery on the planet as those pesky little dendrites gradually form
inside the battery until they cause a short and ignite the volatile electrolyte. Chances
are you'll never witness such a conflagration but when they do happen they're pretty dramatic and in
extreme cases they can shut down sections of a power grid or even threaten lives.
So a great deal of work is going on all over the globe to develop cheaper, more reliable,
more efficient and more environmentally friendly solutions to our rapidly growing energy storage
requirements. And now a world record-breaking zero emissions energy storage facility has stirred into
life which doesn't contain a single lithium-ion battery. So what is this eco-friendly behemoth,
and does it represent another step change in how we power the sustainable societies of the future?
Hello and welcome to Just Have A Think. Before I dive into today's topic I've just got a slightly
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It might not come as a total surprise to you to learn that the new installation I mentioned
earlier is over in China. Seems like just about every new energy initiative they embark upon these
days has some sort of record-breaking dimension to it. This one's called the Zhangjikou power
plant and it uses nothing more complicated than compressed air to store energy. Now I'm sure many
of you, especially in Germany in the States will be yelling at the screen that this is nothing new
and you've had compressed air energy storage for decades. But hang on! Don't click away just yet,
because this new technology is a big leap forward from those existing systems. And don't worry if
you are in North America or Europe or Australia because there are similar projects in development
in your part of the world as well. We'll come to those a bit later in the video. But first of all,
let's take a look at why the installation in China is such a step forward. And to do that we first
need to have a look at how traditional utility scale compressed air energy storage systems work.
The basic principle is dead simple really. When excess power is being generated on the grid,
often from intermittent renewables like wind and solar, that power can
be diverted to drive an industrial scale air compressor which draws air in, compresses it,
and shoves it into a large storage chamber which is typically either a huge pressurized vessel or
something like an underground salt cavern or aquifer. The laws of thermodynamics tell us
that gases get hot when they get compressed, so to ease the process that heat has to be somehow drawn
away from the air. That's a very important step which we'll touch on in more detail in a moment.
When there's a demand for extra grid power the cold compressed air is heated up to
help it rapidly expand so that it can be directed across a turbine to drive an electrical generator.
The world's first compressed air storage system was the Huntorf Power Plant built
way back in 1978 in lower Saxony, Germany. It had a generating capacity of 290 megawatts which it
dispatched with an efficiency level of around 29 percent. A few years later, in 1991, the McIntosh
power plant was opened in Alabama USA with a capacity of 110 megawatts and 27% efficiency.
So how do these plants deal with that heat generation that I mentioned a moment ago?
Well, they both use a process known as diabatic compression. Diabatic is one of those sciency
words that you and I are unlikely to come across in our everyday lives and it sits alongside two
other sciency words - adiabatic and isothermal. All three of them describe how the temperature
of a gas changes as it's compressed or expanded. Adiabatic compression usually happens very quickly
with the gas getting hotter and hotter as it gets compressed. It's what happens as a piston
pushes air in the cylinder inside a diesel engine for example. In that case you want the air to get
extremely hot so that it ignites atomized diesel fuel inside the chamber which then
causes an explosion that pushes the piston back to rotate the crankshaft. At the other end of
the thermodynamic scale is isothermal compression where the temperature of the gas remains constant
as it gets compressed. To achieve that you have to find a way of removing all the heat as the gas is
compressed, either by going incredibly slowly so that the temperature gradually equalizes with the
ambient surrounding air, or by using some kind of non-compressible thermal mass right next to
the gas that's being compressed to very quickly absorb the heat and keep the gas as close to a
constant temperature as possible. In between those two extremes is the diabatic compression technique
used by the Huntorf and McIntosh plants. Diabatic compression is generally achieved with huge
intercoolers which are specialized heat exchangers specifically engineered to cool a gas after it's
been compressed. Most of us probably know of intercoolers in the context of turbocharged
vehicle engines. The intercooler dumps most of the heat straight into the air, essentially
throwing away the energy used to compress the gas. The result of this method is a large amount
of cold air that's been compressed down to as smaller volume as possible and stored in those
underground caverns. The stored air is very cold, which is why the warming step is required to cause
rapid expansion ahead of the turbine. And I'm sure you're at least one step ahead of me here... yes,
you've guessed it, the easiest way to heat up cold air is in a burner powered by fossil gas,
which means the Huntorf and McIntosh plants generate large quantities of
those pesky greenhouse gas emissions. They're like everywhere aren't they? They're really irritating!
But this new advanced compressed air energy storage facility in Zhangjikou uses no fossil
fuel combustion at all. Instead they've developed a technology that draws the heat off the gas as
it compresses and instead of releasing it into the atmosphere they divert it into an insulated
thermal storage facility. Then, when the grid demands extra power, that stored heat can be
put back into the air to accelerate the expansion before it goes over the turbine. The facility has
a generating capacity of 100 megawatts, releasing up to 400 megawatt hours of energy. Capturing that
heat in a thermal storage tank increases the system design efficiency to over 70 percent,
which completely eclipses the efficiencies of the fossil fuel combustion technology used at
the existing Huntorf and McIntosh plants. It's enough to generate more than 132 million kilowatt
hours of electricity a year, serving around 60,000 households during peak electricity consumption.
According to the Institution of Engineering and Technology, or IET, the Zhangjikou plant will
prevent the burning of about 42,000 tons of coal and reduce carbon dioxide emissions by a hundred
and ninety thousand tons every year. But China isn't alone in diving into this very promising
technology. I promised you earlier that we'd talk about opportunities in other parts of the world,
and one of the front runners in the field is a Canadian company called Hydrostor.
They've been on the go for 11 years now and in that time they've developed a very similar
non-combustion system to the one being used in the Zhangjikou plant, with a compressor,
generator, and thermal management system that can capture the heat from the air as it's being
compressed. Hydrostor combines all that with a closed-loop water reservoir providing what
they describe as hydrostatic compensation to maintain the system at near constant pressure
during operation. That means the reservoir water is sent down into these purpose-built subterranean
air chambers where it gets pushed back out again by the compressed air coming in the other side.
Once the chambers are full of air and the reservoir is back at full level the system is
fully charged and it can stay that way for days if necessary. Then when there's a power demand
the reservoir water is pushed back down into the chambers to force the air back up to the
surface under pressure where its temperature is rapidly increased by the stored heat in
the thermal management system before being sent across the turbine. Hydrostor has had to overcome
a range of pretty challenging obstacles to get their technology to market, not least of which
is the very long payback timeline that venture capitalists and other investors have to accept.
Those folks are used to getting a return on their money in about 10 months on average.
But Hydrostor projects can cost as much as 500 million dollars overall and have a payback time
that's more like 10 years, which is longer than some investment funds even run for!
Company Chief Executive Curtis Van Walleghem has shown himself to be a very dogged and determined
operator though, and the company now has several projects on the go in various parts of the world,
ranging from a 10 megawatt hour facility already in operation in Ontario Canada and a UK project
converting a disused gas storage site to some very large installations under active development in
Australia and the USA that'll have generating capacities as high as 500 megawatts. Additional
competition comes from an Israeli technology company called Augwind Energy that's developed
a slightly different solution to the heat loss and efficiency challenge. Their system also uses water
and air but instead of pushing air down into deep underground chambers they use a series of modular
air tanks which they tell us are made of unique polymers that reduce production and maintenance
costs. The tanks are cemented in just below the surface with installation taking just a few days.
Then they use renewable energy to run water pumps to compress the air into the tanks. That has the
secondary advantage of removing a bit of heat from the air as it's compressed, but Augwind run their
system extremely slowly too, which means they stay very close to the isothermal compression
we looked at earlier. Then when there's an energy demand the compressed air is used to push the same
water over a hydroelectric turbine to produce the electricity. It's just a different route to the
same end result. An Augwind claim a very similar efficiency rate to the Zhangjikou plant. They've
been developing their air battery technology for about 12 years now, and they've secured
more than 200 megawatt hours worth of projects in Israel that they hope to get up and running over
the next few years. But in typical fashion China isn't resting on its laurels either.
There are apparently at least nine compressed air energy storage plants there that are either under
construction now or have already entered into service. The total combined capacity of those
plans is 682 megawatts and there are another 19 projects in the planning stages with a combined
capacity of 5.38 gigawatts. By 2030 China expects to have more than 43 gigawatts of non-combustion
compressed air storage facilities in service representing about 23 percent of the country's
total energy storage capacity. There will no doubt be pitfalls along the development pathway
for this fossil-free energy storage technology, especially in western democratic countries.
Getting one of these projects off the ground entails securing the land and interconnections,
seeking community engagement and applying for all sorts of permits and regulatory approvals. But the
prize for patient investors could be very large indeed. According to a recent McKinsey report,
long duration energy storage has the potential to deploy as much as two and a half thousand
gigawatts of power capacity by 2040 to become the vital key to unlocking 24-7 clean grid energy in
a more sustainable future world. So what's your view? Do you think this advanced compressed air
solution could be a market disrupter that displaces the dominance of Lithium-ion
batteries? Maybe you work in the industry and you can share some insight with us all.
If you do, then why not jump down to the comments section below and leave your thoughts there?
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