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Grid-scale lithium-ion batteries are our current go-to chemical energy storage solution, but
they present their own challenges in safety, sustainability, cost, and longevity. However,
the competition is … heating up. New forms of thermal energy storage systems built using
abundant, cheap materials are on the rise. One company is aiming to sidestep the complications
that come with chemical batteries…with bricks. And another company’s weapon of choice is
crushed volcanic rock. Talk about going back to basics to store massive amounts of energy.
But is simple really best?
I’m Matt Ferrell … welcome to Undecided.
Why are people looking to store energy in bricks and crushed volcanic rock? It shouldn’t
be a shocking revelation to say that renewable energy like solar and wind is intermittent.
The sun doesn’t always shine and the wind doesn’t always blow, so we need to have
cheap, reliable energy storage to save excess renewable energy production for when we need
it. How much renewable energy are we losing out on? A 2022 report by Lane Clark & Peacock
for Drax estimates that enough wind energy to power 800,000 homes in the United Kingdom
went to waste over two years due to lack of storage.
So, to make the most efficient use of our wind and solar power, we need more reliable
storage. On a grid level, lithium-ion batteries have considerable perks. They boast a high
energy density, a high round-trip efficiency, and decently long cycle lives. However, Li-ion’s
advantages are costly in more ways than one. Lithium is expensive, extraction is slow and
not always environmentally friendly, and it has a lot of price volatility. Li-ion batteries
also don’t last as long as some other forms of energy storage tech.
Thermal energy storage (or TES) systems are heating up as an appealing alternative. For
one thing, TES systems don’t necessarily require converting energy (keeping heat as
heat), which means higher efficiency. In district heating systems or industrial applications,
which we’ll talk about more later, the heat put into the battery is taken right back out
as-is.
Another significant edge is that TES systems are based on tech that’s more down to earth.
We’re talking batteries that store excess energy as heat in water, molten salts, sand,
gravel, and, more recently, brick and rocks. With these materials at the core, you don’t
have to worry about scarcity, environmental impact, or explosions. They don’t degrade.
And they’re _cheap_.
This is the foundation that the California-based company Rondo Energy and the Israeli company
Brenmiller Energy built their TES systems upon. They’ve each developed heat batteries
offering similar benefits in almost identical language: low-cost heat that can be stored
for hours or days, decades-long lifespans, “unlimited” cycles free from performance
degradation, zero emissions. These batteries operate using bricks and rocks, respectively.
Both companies promise similar outcomes, emphasizing reduction in the costs and the emissions associated
with the industrial sector. They also both happened to make notable moves in November
2022. Early that month, Brenmiller inaugurated its latest project: the testing of a utility-scale
TES at a thermal power plant in Italy as part of a collaboration with Enel, Europe’s largest
energy company. A week and a half later, Rondo officially announced the launch of its Rondo
Heat Battery or “RHB.”
How does brick and rock translate into efficient heat storage?
Before I get to that, I’d like to thank Incogni for sponsoring this portion of today's
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the channel. Now back to how brick and rock translate into efficient heat storage.
Let’s start with Rondo. Its heat battery has been likened to a giant brick toaster,
and the company’s CEO, John O’Donnell, has also referred to it as an “insulated
shoebox full of brick.” I don’t want to know what kind of shoes he’s wearing. When
the battery is charged, renewable energy from wind or solar, or electricity from any source,
is converted into heat by its oven-like electric heating elements. This thermal radiation fires
up the thousands of tons of bricks inside, which can reach temperatures up to 1,500 C.
The battery can store this energy for hours or days.
The company claims that a RHB can last over 40 years, with several of its individual components
able to last even longer, as well as being recyclable. As O’Donnell pointed out in
an interview last June, their bricks are “inert, and known to last for 100 years.” This also
means that their systems don’t contain anything that, in his words, “can physically spill
or release gas, or catch fire.”
Once you want to pull the heat back out of a RHB, a blower sends air up through the bricks.
The air is superheated to above 1,000 C, and the end result is heat in the form of superheated
air or superheated steam released on demand. These high temperatures are especially useful
in industrial applications, which is Rondo’s main target. RHBs are intended to directly
replace fuel-fired boilers, furnaces and kilns.
Here’s where we need to zoom out to get the full picture. Heat is central to a massive
number of industrial processes, from sterilization to smelting. A 2014 study by the U.S. Department
of Energy estimated that the country’s industrial sector uses about 24 _quadrillion_ Btu, or
British thermal units. Btu measure the amount of heat it takes to raise the temperature
of one pound of liquid water by 1 degree Fahrenheit. 24 quadrillion Btu is equivalent to roughly
a third of the United States’ delivered energy supply. It’s a lot of energy.
Fossil fuels continue to be the primary source of energy for factories precisely because
burning them is a quick and easy source of heat. As you might expect, that has major
consequences. According to the International Energy Agency, a quarter of the world’s
emissions — about 9.4 Gt of CO2 — were directly produced by industrial activity in
2021. It’s important to note that this figure doesn’t include the indirect emissions from
the electricity used to power them.
Within the broad category of industry, the top three emitters of greenhouse gasses include
the production of iron and steel, chemicals and plastics, and cement. The influence of
cement in particular is pretty shocking: If it were a country (a really drab, gray country),
it would be the world’s third-largest CO2 emitter behind China and the U.S. 70% of the
emissions released by cement-making come from the chemical reaction that produces clinker,
its main ingredient. So, the recipe shoulders most of the blame. But the remaining 30% is
a result of using fossil fuels to fire up the furnaces.
Cement is a component of concrete, and concrete is the most-consumed material on the planet,
second only to water, which is kind of crazy. On a global level, cement and concrete production
accounts for 8 to 9% of greenhouse gas emissions and 2 to 3% of energy demand. But while concrete
isn’t going away anytime soon, maybe its reliance on fossil fuels can. This isn’t
just about reducing emissions though, it’s also about saving money.
This is where Rondo is stepping up to help. Last July, the company announced its collaboration
with TITAN Cement Group. The goal is to reduce emissions that would otherwise come from burning
fossil fuels by using Rondo Heat Batteries to capture energy from kiln flue gasses, then
taking that heat to produce clinker. Later, in September, Rondo announced a partnership
with Siam Cement Group, which also produces chemicals and paper.
So far, RHBs are making a big difference, according to Rondo’s claims. On the date
of the battery’s commercial launch, the company’s Senior Vice President, Jeremy
Keller, said that facilities outfitted with RHBs are “showing 50% to 90% reductions
in emissions and reductions in operating costs of 30% or more.” A nice one-two punch on
emissions and costs.
Rondo also claims a whopping 98% efficiency, which the company’s YouTube channel clarifies
is because “the roundtrip efficiency of basically all electric thermal energy technologies
will be in the 95%+ range.” In O’Donnell’s words, the conversion of electricity to heat
happens at 100% efficiency every time you turn on a heating appliance. We’re back
again to the toaster metaphor. Get your Pop Tarts ready.
As for Brenmiller Energy, its line of bGen batteries work like RHBs and are trying to
accomplish the same thing: provide industry with a clean source of heat. The main differences
are that bGen batteries stick within a lower range of 100 to 500 C for heat output, and
instead of bricks, Brenmiller uses crushed rocks.
Executive Vice President of Operations Nir Brenmiller explains that rocks store heat
inside “cells that are stacked into a module, then into a pack.” Electricity or heat goes
in, and hot water, hot air, or steam comes out. The energy input can be anything from
exhaust heat, surplus steam, electricity straight from the grid during peak hours, wind, solar,
or biomass. Dealers choice.
For example, Fortlev, Brazil’s largest manufacturer of water storage products, began using a bGen
unit at its factory in Anápolis, Brazil, last August. The company needs hot air to
run its machines that mold plastic into water tanks, and its 1MWh bGen battery allows the
company to swap natural gas for biomass. Brenmiller claims that by making this switch, Fortlev
lowers the fuel costs of heating air by over 75% and lowers its greenhouse gas emissions
by about 800 metric tons a year.
The bGen BS-7011 (a name that rolls off the tongue) is charged by the combustion of wood
chips or pellets and boasts an 80% efficiency. That said, burning wood and wood pellets in
the name of sustainability is a controversial subject to say the least. The potential effects
depend on where exactly that wood is coming from. But the use of biomass as fuel could
be a video subject all on its own. If you would be interested in that, let me know.
And if the concept of using earthy materials to store heat sounds familiar, you might be
thinking back to the sand battery built last summer in a small Finnish town by the country’s
own Polar Night Energy, which I covered in a previous video. Like Rondo and Brenmiller’s
batteries, the sand battery is a TES system that takes advantage of excess renewable power
to squirrel away heat until it’s needed. The sand battery is already warming homes
and offices through the local district heating system. And like the sand battery, district
heating is a potential application for both Rondo and Brenmiller’s tech.
District heating is basically an underground network of pipes that delivers heat to buildings
from a central plant. It offers a great opportunity for decarbonization by using renewable energy
to distribute steam or hot water instead of relying on individual boilers. As a concept,
it’s actually been around since the use of geothermal water to warm houses in Pompeii.
These days you can find this kind of infrastructure all over China and Europe. There’s also
over 660 district energy systems throughout the United States, including in major cities
like New York and San Francisco.
In fact, Brenmiller has already been collaborating with the New York Power Authority since 2017.
In 2020, the company installed a cogeneration system, which generates both heat and electricity
at the same time, in the P.E. building of Purchase College at the State University of
New York. This replaced its existing district heating loop. The system takes exhaust from
a turbine and uses it to provide about half the building's electricity alongside all its
heating and hot water. More recently, during a December 2022 call with Brenmiller Energy
investors, Nir Brenmiller said that the partnership is currently “examining solutions for industrial
manufacturing and for district heating in big buildings in cold locations.”
These examples only scratch the surface of what’s possible. For a deeper dig into energy
that travels underfoot, check out City Beautiful’s video on district heating. It’s a great
YouTube channel and they’ve just released a video about this.
Now, back to the batteries and some of the gotchas, or potential cons, about the tech.
Rondo and Brenmiller share another trait: Despite both companies’ heavy promotion
of their products’ potential for industry, these things just don’t get hot enough for
steelmaking. Getting serious about decarbonization requires that we tackle steel specifically.
The industry was responsible for over 3.3 billion metric tons of greenhouse gasses in
2021. Meanwhile, wind turbines are, ironically, mostly made of steel.
For now, Brenmiller is deliberately focusing on supplying medium range temperatures, citing
the complexity of integration into steel factories. This caveat also means no cement. That’s
not to say that bGen batteries can’t do much: in European countries, 30% of industrial
heating applications require temperatures of less than 100 C. Another 27% do just fine
with heat between about 100 and 400 C, which is well within a bGen’s maximum of 500 C.
Rondo provides a higher temperature range, but its upper limit is 1,500 C. You need at
least 1,600 C to produce steel. O’Donnell did say in an interview, however, that it’s
possible for the Rondo Heat Battery to hit 1,800 C in the future.
In other words, things are only just getting started. RHBs haven’t been commercially
available for long and neither have Brenmiller’s pilot projects in Brazil and Italy. Brenmiller
also has another TES in the works: a $9.2 million, 31.5 MWh bGen unit set to replace
the boilers in a Philip Morris tobacco plant in Romania. For me that raises the question
of, “why a tobacco plant?” Anyway … they plan to break ground in early 2023.
So, we still have to wait to see what these batteries are really capable of. In the meantime,
thermal storage is continuing to gain traction, with plenty of TES systems in development
across the globe. Two of the largest upcoming projects are both 600MW molten salts plants,
one in the United Arab Emirates, and another in China. Let’s hope they can do more than
toast.
So are you still undecided? Do you think storing heat is a smart move? Jump into the comments
and let me know. And be sure to check out my follow up podcast Still TBD where we'll
be discussing some of your feedback. If you liked this video, be sure to check out one
of these videos over here. Thanks to all of my patrons, who get ad free versions of every
video, for your continued support. And welcome to Support+ member Paul Maack and Producer
Rick Cosgrove. You're helping to reduce my dependence on YouTube to pay for producing
these videos. And thanks to all of you for watching and commenting. I’ll see you in
the next one.