Let me set the scene: You finish work late one evening, you come home, turn the lights
on and put a pizza in the oven. It’s quite a hot evening as well, so you turn a fan on.
While your dinner cooks, you sit down and watch
the hot new viral video that everyone is talking about.
Right now millions of people are doing the same as you, so those good folk over at the electric grid
see a sharp rise in demand, and they increase production at power stations to meet it.
You have a great evening, with delicious food and excellent entertainment.
Now imagine a different scenario.
The world you live in is pretty much the same,
except fossil fuels were eliminated a long time ago.
But there’s a problem: the sun went down at 6pm and there’s no wind. The folk at
the grid are panicking as they’ve got no way to increase power production.
Meaning once again there’s no lights to turn on,
no pizza, no video and worst of all … you might still be at work!
*Blood curdling scream*
OK so that might all have been a bit extreme, but there is a big problem
with renewable energy and I’m not talking about how much, or how little, we use.
While we might be used to seeing more wind turbines and solar panels in recent years, for
the green energy revolution that’s only half the solution. We also need lots of battery storage.
In the past the question of “what happens when the sun doesn’t shine and the wind
doesn't blow” was more of a hypothetical problem, but with renewables making up
an ever greater percentage of our energy mix, it’s now a serious problem that needs solving.
In the UK, the National Grid is trying to increase its storage capacity to 200 GWh by
2050 to reach net zero targets. That’s a whopping 640 percent more than it could store in 2021.
You may think the first choice for this surplus storage is lithium ion batteries.
These are the gold standard for short term energy storage – it’s the same kind you’ll
find in your laptop or electric car – and in 2020 the UK opened its largest lithium ion facility.
But here’s the catch: even if lithium ion batteries were useful for long term storage,
which they’re not, and if mining the raw materials wasn’t terrible for the environment,
which it is, there’s just not enough of it in the world to meet demand.
So the folks back in the control room might be able to draw a little bit of energy from lithium
batteries, but another lever they may want to pull is marked “Pumped-Hydro”, here’s how it works:
When energy is abundant, water is pumped uphill to a reservoir.
When more power is needed in the grid, water is released to a lower reservoir,
turning a generator on the way and producing electricity.
It's a clean, elegant, tried and tested solution. In fact, it’s already the
biggest form of stored energy in the US. But: It’s expensive and takes up a lot of land.
Which is why another technology is being looked to as the future of green energy: gravity
fed batteries. The principle is similar to the pumped-hydro, instead of water a weight is lifted
up using power from the grid, then when power is needed the weight is lowered, producing power.
One way this is being explored is by Scottish start-up Gravitricity,
who are planning a trial in an abandoned mine in the Czech Republic.
But if you don’t happen to have a spare mine shaft lying around
then don’t you worry because there’s a more high-tech option: Energy Vault.
We started with combining software with some innovation in structural
engineering to essentially mirror what is most of energy storage today.
What we're doing is mirroring that process and utilising instead of water these composite blocks.
Through the night, for example, when consumption of energy is very low. So there's excess potential
energy that then can be used to raise those blocks at height. And then when the energy's needed,
of course, they're lowered, it turns the motors that generate and discharge the electricity
Just like a mine shaft battery, Energy Vault generates power by
driving a turbine with a gravity fed weight. The main difference between the two, though,
is that where a mine shaft uses one single weight,
a typical Energy Vault would use thousands, all housed in a structure above ground.
Energy Vault says the benefit of this is that it can serve the needs of multiple
customers at any one time, with the power input and output controlled by software.
And unlike pumped hydro or a mine shaft, these can be constructed pretty much anywhere.
We decoupled energy and power with our design… That means that essentially the customer can
define how much power output they want and how much storage duration they want. And we build
it out in a modular way like any building. So a customer could decide to discharge 25 megawatts
over 4 hours and that would be 100 megawatt hours of storage capacity…. So versus, you know,
versus a single mine shaft with a single weight, it's very difficult
to get economies of scale. You know, you're essentially limited to where you deploy to
where there’s 200 metre holes in the ground. But what makes it attractive is also what’s
brought energy vault some criticism. Unlike pumped-hydro or mine shaft batteries there’s
a big materials cost to creating these vaults, which some say could outweigh any carbon savings.
For any gravity solution like pumped hydro,
we have to build a structure. We use very little steel in our solution. So for example,
we're using a fibre reinforced concrete material for the structure.
The composite blocks are about 25 metric tons each …
those are all made locally so we don't transport them. That reduces greenhouse
gases from the transport sector, which is one of the highest one. So we we make that
all on site utilising the soil as a default solution, but can also use waste materials.
Energy Vault has come a long way from its initial design.
Whether or not it takes off remains to be seen,
but what’s important is that we have a variety of solutions to support renewable energy.
As different technologies come to maturity they may succeed or fail. So,
placing bets on many different types stops us from being overly reliant on any one solution.
Hopefully a few years from now you can relax safely in the knowledge that although it’s
a still, dark night your power could be coming from chemical batteries, water,
mines, Energy Vaults or all of them at once.
You can learn more about how to solve the battery crisis and the other topics on our
channel over on the energising World’s Best Construction Podcast – available now wherever
you get your podcasts. And as always, if you liked this video and you want to learn
more about where construction is headed, make sure you’re subscribed to Tomorrow’s Build.