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If I was to ask you today what technology breakthrough the world needed most right now.
What would you say? This needs to be a technology that we could realistically develop in the
next 10 years. So none of that sci-fi non-sense. This is something I think a lot. Nuclear Fusion
or cheaper, safer and cleaner fission energy are good candidates. Human society would be
transformed by economic fusion power, but fusion is most certainly not a technology
that can be commercialized in the next 10 years. Many people are working on safer and
cheaper nuclear fission, but that too has many hurdles to overcome. I think about how
the world would change if carbon nanotubes somehow became a viable material. A new stronger
and lighter material of carbon nanotubes calibre wouldn’t open doors to new design possibilities,
it would open portals to new dimensions. But that again is not going to happen any time
soon. No, if I was to pick one technology that would have the biggest impact on our
society today, that is within grasp, it would be cheap, scalable energy storage for the
grid.
The electricity grid works nearly entirely on a just in time manufacturing method. We
generate the electricity just as it’s needed. There is no warehouse of electricity that
we can dip into.
Pumped hydroelectricity does provide some storage and is a nearly century old technology,
but is not scalable to our current needs.
Lithium ion batteries are our best option right now. They have proven their worth in
the Hornsdale Power Reserve in Australia. It was commissioned primarily as a fast frequency
response service. [1] This means it can act as both a load when the frequency of the grid
gets too high, or as a power source when the frequency of the grid gets too low. Kind of
how a flywheel maintains the rotational speed of an engine.
You see our grids are designed to operate a particularly alternating current frequency.
If the grid deviates from that frequency, it can cause all kinds of issues that generally
just result in protective measures being activated to protect the infrastructure, and ultimately
cuts power to it’s users. A blackout.
South Australia was struggling with these blackouts.
In 2016, tornadoes ripped through South Australia and damaged some power lines. This caused
the voltage and frequency of the grid to deviate from its baseline. [2]
This caused the wind turbines to trip their protective measures and lower output. Now
this was a massive problem because this is what South
Australia’s power generation looked like on that day, with nearly 50% of their power
coming from wind. [3] To deal with the sudden decrease in output in wind the interconnector
to Victoria attempted to increase its power transfer, but rather quickly shut itself down
to prevent the line frying itself.
The grid basically did the technological equivalent of a human passing out when seeing a drop
of blood. A chain reaction of panic. Leaving 850,000 people without power.
In response, the Australian Energy Regulator is trying to sue the wind companies it had
approved for not doing a job they were not capable of doing in frequency regulation.
[4] I feel like they only have themselves to blame. South Australia had built far more
wind power than it’s grid could reliably handle. It lacked the necessary interconnections
to neighbouring grids and energy storage facilities like pumped hydro, batteries, or simply reserve
power natural gas plants. It was a poorly planned grid. Instability was inevitable.
We are thankfully learning from these mistakes, but as renewables grow the challenge of preventing
blackouts like this is only going to grow. We won’t just need fast frequency response,
but we will also need load shifting. Where we have enough storage to charge batteries
when renewables are available and discharge them when it isn’t. This is going to be
expensive.
Lithium ion batteries are the cheapest we have right now, but when it comes down to
it, they weren’t designed for this job.
They are designed to be light and energy dense for portable electronics, but for a stationary
battery that's a pretty useless trait to have. It’s like having an underwater hair dryer.
Just doesn’t make sense.
Lithium ion batteries are the cheapest form of energy storage available because their
mass market adoption has allowed for the economics of scale to reduce their price, but what if
we designed a new type of battery. A battery that was designed from the ground up specifically
for the grid. To learn more about this, I spoke with Donald Sadoway, a renowned professor
of materials chemistry at MIT and founder of liquid metal battery company Ambri.
Cut to Prof Sadoway interview:
The last thing I do is seek the advice of the incumbents. The incumbents are threatened
by radical innovation. You realize that the lithium ion battery did not come from the
battery industry. The battery industry refused to even manufacture the lithium ion battery.
So Sony, Sony wanted a better battery to power their handheld devices
And this is 1990. And Sony goes to all of the big battery producers in Japan , And they
go, and they say, here's the here's the formulation, build this. And here's a purchase order for,
pick a number, some 10s of millions of dollars. And each and every Japanese battery manufacturer
said, “No, I’m not building that.” “We have all this capital investment in the manufacture
of nickel metal hydride batteries. We can't build this battery in that plant.” And so
they said no.
And somebody at some point said, you know, if we want to have lithium ion batteries for
appliances. There is only one way we are going to have them. We're going to build them ourselves.
And Sony says “We aren’t a battery company” says, “We need batteries. And there's only
one we're going to get them we're going to build them ourselves. And so Sony built the
first lithium ion battery manufacturing facility.”
And very soon thereafter, they were getting inquiries from people who are building mobile
phones, saying can we have those? And then people who are building mobile computers,
laptop computers, can we have those? And by 1995, nickel metal hydride was pretty much
displaced.“
So what battery chemistry is Prof. Sadoway is trying to build and can it have the same
revolutionising disruptive effect on grid storage that lithium had for consumer electronics?
The idea started simply. Professor Sadoway had decades of experience in electrolysis
refining for metals like iron and aluminium. That process takes a lot of energy to refine
the metal. Why not try to make that process reversible and allow the reverse reaction
to give electricity back.
This is the basic concept of liquid metal batteries. We alloy and de-alloy metals in
a perfectly reversible reaction. They don’t need to be light. They need to be cheap. And
as Prof. Sadoway says
“I say, if you want something to be dirt cheap, make it out of dirt”
So how do we go about choosing materials for a battery like this? What does the design
ideation phase look like? Professor Sadoway is a professor of Materials Chemistry at MIT.
Looking at a periodic table is a different experience for him.
This is what he sees when picking materials for a technology like this. For the liquid
metal battery, we first need to refine our search down to metals and metalloids, which
are these elements.
Next, we need to maximise the difference in electronegativity to maximise our voltage.In
general, electronegativity is highest on top right of the periodic table and lowest on
the lower left. So, our electrode materials can be further narrowed down to elements in
these two groups. [5]
Next, as Prof. Sadoway said, if we want our battery to be dirt cheap, we have to make
it out of dirt. So let’s plot our relative abundance of elements. [6]
Of the candidate elements for our negative electrode, Calcium is by far the most common.
Which is the negative electrode for the Ambri Liquid metal battery. However, they didn’t
arrive at their current electrode materials just by analyzing the periodic table. Experimentation
was vital as this is a complex and dynamic system. They have tested several combinations
of different electrode materials from these two groups, and there are a lot of complicated
interactions to consider. [7]
Ambri has landed on a Calcium Antimony cell chemistry. So how does it work?
These materials are placed into a ceramic insulated cell together. When a current is
applied the materials begin to heat up. Eventually they will turn liquid and the metals will
separate naturally as a result of their density differences. The heavier positive electrode
sinks to the bottom with a neutral density electrolyte separating the lower density negative
electrode on top. This makes building the cell very simple. Lithium ion batteries use
complicated coating processes to build their electrodes.
This is the charged state, now when a load is applied the opposite electric current is
experienced. This causes the calcium electrode to break into a calcium cation and 2 electrons.
The cation travels across the electrolyte bridge and combines with the antimony and
the electrons that have travelled on the external circuit to form a new alloy. This continues
to happen until the calcium electrode is completely consumed. Now we just have the new mixed alloy
and the electrolyte. This is the discharged state. To get back to the charged state we
simply apply the opposite current and the reverse reaction occurs and creates a fresh
battery.
Now this brings another advantage. Lithium ion batteries degrade over time. As they are
charged and discharged, chemical reactions occur that damage the electrodes and reduce
their ability to hold a charge, and many of the ways we need a load shifting battery to
operate are the exact ways that accelerate this degradation over time.
Taking a lithium ion battery from full to zero charge is particularly damaging. As few
as 500 deep cycles, can reduce the capacity of the NCA batteries that Tesla uses by as
much as 20%. [8] That represents about a year and 4 months of daily use for our load shifting
battery, whose job will be a daily one.However LFP batteries, which Tesla has started using
in it’s Chinese Model 3s, degrade much slower even under deep cycling and they have stated
that they will use LFP batteries for stationary storage in the future. Depending on the temperature
they operate at LFP batteries drop to 85 to 95% capacity after three thousand cycles.
Higher temperatures result in higher capacity drop.
However, Ambri have shown that their capacity fade is minimal even after 5000 cycles [9],
thanks to the continual creation and destruction of it’s electrodes. Allowing us to fully
discharge our batteries on a daily basis for upwards of twenty years.
However, as I’m sure you have been wondering, keeping the calcium and antimony electrodes
so hot that they melt comes with disadvantages. For one, we are going to lose some of our
electricity to heating the materials up to operational temperature. This reduces our
round trip efficiency.
So, to explain it, if you put 100 units of electricity in, there are some losses because
there's some joule heating, and so on and so forth. With liquid metal battery, it's
about 80%. Because the difference, the 20% is the energy lost desirably to heat the battery
to keep it at temperature. So you say wow, 80%, that's 20% loss. What's up with that?
The round trip efficiency of pump hydro is 70%. So we're better than pumped hydro. But
the thing is that this is a case of don't don't answer irrelevant questions, because
the key question is, what is the cost of electricity.
So this is where things get a little complicated, luckily we have an equation to calculate the
levelized cost of electricity storage. [10] It’s determined by the total costs, which
are the sum of the initial capital cost, the continual operations and maintenance cost,
the cost of charging and the end of life costs, divided by the total electricity discharged.
Based on Ambris calcium-antimony cell chemistry, the cost of electrode materials vastly undercuts
current generation lithium ion batteries. With the total cost of the liquid metal battery
electrode materials coming in at 17 dollars per kiloWatt hour versus 51.2 dollars per
kiloWatt hour for the most common nickel manganese cobalt batteries. [11]
If they manage to get the initial capital cost down 66%, that decrease in round trip
efficiency is a minor concern.
These continual costs are hard to predict. Operations and maintenance costs for lithium
ion batteries could include buying more batteries to bring total capacity back in line as the
batteries fade. We also have very little data for end of life costs, which will primarily
be determined by how easily disposed of or recyclable the batteries are. For both of
these metrics, liquid metal batteries will likely have an advantage.
However, even with the promise of liquid metal batteries, Lithium ion batteries have a major
leg up on any potential competitors. They have had decades to work on the manufacturing
process and reduce their price, and they are still getting cheaper.
Ambri have proven this cell chemistry works on the bench scale, but actually bringing
a product to market is much harder than proving the science works.
“It's simply the the long journey from lab bench to, to marketplace. We, you know, here
at MIT, I with my my team of students and postdocs, we worked on this. I had a concept
and then we we reduced it to practice and then got it to the point where we said it's
time to start a company.Now, how do you take that and turn it into a marketable product
that is able to be manufactured? At the university, you know, you make five cells and one of them
works and you get a publication out of it and everybody's high fiving and so on. But,
but in manufacturing, you have to have, everything has to work. So, so we had to design the manufacturing
process. And there's nobody to turn to there's no there's no model. I can take the most brilliant,
the most competent people in the lithium ion battery sector. And almost everything that
they know is in applicable because they're the lithium ion chemistry is different, which
means that the format of the battery is different. their needs are different. I mean, they have
to guard against thermal rise, we have to guard against thermal fall. We want to keep
our batteries hot, they're trying to prevent their batteries from getting hot.
And there are dielectric hermetic seals that have to survive 500 600 Celsius. So obviously,
they're going to have to be ceramics. But ceramics are brittle, fragile, and they don't
like thermal excursions, but we have to be able to, to endure thermal excursions, and
I can give you a ceramic and you can do it like that. But it's going to cost something
around a NASA price point”
Designing an entirely novel product is not easy. Those dielectric hermetic seals in particular
are a tricky bit of engineering. They need to be dielectric, to separate the positive
and negative electrodes. They need to form a seal to prevent gases and moisture from
entering the battery and causing corrosion and secondary reactions. It needs to be corrosive
resistant as those molten salt electrolytes can corrode many materials and to boot it
needs to be heat resistant since the battery operates at 500 degrees celsius. Those are
4 very specific combinations of material properties that don’t come with an off the shelf rubber
o-ring.
It’s one thing to design a prototype that works, but it's an entirely different beast
to design a product that can be manufactured cost effectively and reliably.
When lithium ion batteries first came to market in the 90s, their price per kilowatt hour
was upwards of three thousand dollars, but over the past 3 decades that price has continually
dropped to about 150 dollars per kilowatt hour. [12]
There is no scenario where Ambri comes out of the gates at this price point, no matter
how cheap their electrode materials are, the price of a novel manufacturing method will
offset any cost savings until economies of scale take over.
This difficulty of bringing a new technology to market, despite the obvious potential advantages,
is called technological lock-in. And it makes it incredibly difficult for newcomers to enter
the market. If they can’t compete with cost straight out of the gate, they are going to
struggle to find buyers.
In order for new products like this to get to market and start their journey to affordability,
they often need to find a niche market where their advantages outweigh their cost. So where
could liquid metal batteries find this niche market?
As we explained lithium Ion batteries are temperature sensitive. Without proper thermal
management lithium ion batteries will at best degrad faster, but they can also malfunction
or even catch fire. [13]
This has already happened, with a large grid scale lithium ion battery in Arizona. Where
battery degradation led to a thermal runaway. In other words a rack of batteries failed
and caught fire. [14] Leading to the shut of every battery storage facility in the state
until the cause of the problem was found.
These disadvantages of lithium ion batteries are exactly what is going open the door for
liquid metal batteries. The liquid metal battery can work just fine in extreme conditions.
After all, the entire product is designed to operate at 500 degrees. No cold or warm
environment is going to interfere with its operation. Making the battery better suited
for hot weather climates.
In an application where the batteries need to operate in a warm climate, while being
used daily and under deep cycling, liquid metal batteries may be able to justify their
initial high price for the right early adopter, and that’s exactly what has happened.
Terrascale is a data centre company that is building a scalable data centre that will
operate on it’s own renewable microgrid in the warm desert climate of Reno, Nevada.
It has already built 23 Megawatts of geothermal and 10 Megawatts of solar, as part of their
phase one 20 MegaWatt data centre. [15] This will be attractive to companies wanting to
use green energy to run their servers and companies that want to shield their data from
potential power outages or even cyber attacks through grid vulnerabilities, which have become
increasingly common over the last decade. [16]
This microgrid will shield Terrascales customers data from such vulnerabilities, but to run
on renewables reliably they are going to need a lot of energy storage and for that they
have turned to Ambri. Announcing very recently that they will partner with them for a massive
250 MWh battery that will begin construction in 2021. Enough storage to run that 20 MW
data centre for 12 and half hours straight.
This will be an excellent test of the technology, and I for one will be following it closely,
because if it succeeds it’s going to revolutionize how our grids operate. Forming that missing
link of renewables.
We spoke with Professor Sadoway in far greater detail about his work with liquid metal batteries,
but it’s difficult to squeeze all that detail into a YouTube video. That’s why we started
Modulus, a podcast hosted by me and Stephanie from Real Science. A podcast where we will
dive into the people behind the scientific stories we tell you here on YouTube. We will
talk to the scientists who are on the cutting edge of research, and the people who are affected
by the topics we discuss.
We learn what it’s like watching your life's work descend onto the Martian surface with
Bobak Fedowsi. We get inside information with people like Professor Sadoway pioneering revolutionary
technology.. This podcast will show the real life people behind these topics, and the real
life impact these scientific stories have on the world.
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