This video was created in partnership with Bill Gates,
inspired by his new book “How to Avoid a Climate Disaster.”
Earth’s climate is changing rapidly. The world is heating up. These are undeniable facts,
and the culprit for this very recent, very rapid change is us. With the help of fossil fuels,
humans emit billions of tons of carbon dioxide into the atmosphere every year. But, when you
think of carbon emissions you probably imagine the cars on the road, the power running your apartment
or even the electricity in the lightbulbs above your head. If we look at the breakdown of the
51 billion metric tons of greenhouse gases we emit every year, however, electricity only accounts 27%
of the problem. It’s not even the biggest sector in terms of emissions.
That award goes to the oft-forgotten manufacturing sector. Emissions from manufacturing come from a
wide range of building materials like plastics, steel, glass, aluminum. But,
today we’re going to zoom in on one of the most polluting materials in the manufacturing world,
which is also one of the least mentioned materials in terms of emissions: cement.
The Problem with Cement
We build a lot of stuff, and a lot of that stuff, from the Three Gorges Dam to the Sydney Opera
House, is built with concrete, which is a mixture of sand or gravel and a cement paste. Globally,
we produce 4.1 billion tons of cement every single year. The U.S. alone creates roughly 96 million
metric tons and China develops over half of the world’s cement at 2.2 billion per year. We use
so much of it because to be quite honest, it’s the perfect building material. Concrete is extremely
durable, versatile, inflammable, and weatherproof. But concrete also has a large downside. In order
to create cement (and ultimately concrete), you also have to emit a lot of carbon dioxide. In
fact, for every ton of cement made, a ton of carbon dioxide is released into the air. This
happens because of a particular chemical reaction that occurs when raw materials are turned into
finished cement. After raw limestone and clay have been ground up and mixed with other materials like
ash, they are fed through a massive cylindrical kiln that gets heated up to 1450 degrees celsius.
Within these large kilns, a process called “calcination” occurs wherein the raw materials
are split into calcium oxide and carbon dioxide and the final product becomes solid grey balls
known as clinker. The byproduct of conventional cement, then, is carbon dioxide. CO2 emissions
from the chemical process account for 50% of cement’s total footprint. Another 40% of
cement’s emissions come from the burning of fossil fuels to heat the kiln up to extreme temperatures,
and the final 10% comes from mining and transporting raw materials. In short, 90% of the
CO2 emissions from cement come from what happens in and around that big cylindrical kiln. As a
result of these emissions, the cement industry generates 2.8 billion metric tons of CO2 every
year. That’s 8% of the total global CO2 emissions. This means that, if left unchecked, the growing
cement industry could prove a huge obstacle to getting to zero emissions by 2050. It also
means that cement offers a chance to drastically reduce global emissions quickly if done right.
Concrete Solutions: When it comes to greening the cement industry,
there are a lot of proposed solutions. From geopolymers that harden at room temperature,
to using bacteria to grow concrete blocks, innovators are all scrambling to find the
next alternative cement. One of them, a 2013 startup called Solidia, represents an exciting
development in the world of cement. The company has developed an alternative chemical process for
cement which reduces both energy use and emissions by 30% during the manufacturing phase. But the
most promising part about Solidia’s cement is that they use CO2 instead of water in order
to harden their concrete blocks. This means that not only does Solidia cement conserve freshwater,
which, for an industry that accounts for 9% of total global industrial water use is huge,
but it also means that Solidia’s concrete blocks can sequester carbon. As a result
of the decreased energy demands, reduction in emissions in the kiln process, and the absorption
of carbon during curing, Solidia claims they can reduce cement’s carbon footprint by 70%.
Meanwhile, in Silicon Valley a startup called Blue Planet is approaching the cement problem
from a different angle. They’ve developed a technology to create synthetic limestone
aggregates, which are basically just rocks, by capturing carbon emissions from flue gas. This
synthetic aggregate can then be used to replace the traditional materials like sand and gravel
in the final concrete mix. Blue Planet claims this low-cost carbon sequestration method
could theoretically offset all of the emissions from the cement creation process.
In essence, the amount of carbon that Blue Planet’s synthetic limestone captures could
potentially equal the amount of carbon the cement production process creates.
Pipe Dreams or Realities? These solutions, however,
aren’t without barriers. Solidia’s cement curing process can only happen at a factory,
which means it’s applications are limited compared to conventional cement. Blue Planet’s aggregate
process only comes in after the cement has gone through the kiln, meaning that its carbon capture
properties are really just trying to make up for the emissions created during the kiln process.
On top of all of that, both these companies have yet to really hit the market and be proven at
scale. In short, these alternatives have a long way to go in part because they’re entering an
industry where safety and durability are king, so in the eyes of builders and safety inspectors the
tried-and-true conventional cement almost always trumps new varieties and inventions. Which means
that without significant government backing and policy change, the concrete industry will
stay rigid. But we should not just wait for new technologies to hopefully save us one day, the way
we build and how much we build can also greatly influence how much cement we use. According to
a research paper by Chatham House, designing cities based on a “capillary web system” could
decrease car use by two-thirds and cement demand by one-third. If employed in places like China and
India where construction is booming, this type of smart design could mean huge reductions in
concrete use and ultimately emissions. At the end of the day, developing new technologies is just
one part of our global concrete problem. Only combined with government policy, smart design,
and reducing consumption, can we truly create the building blocks of a zero carbon world.
Bill Gates’s new book, “How to Avoid a Climate Disaster,” does a great job outlining the
technical challenges that lay ahead of us in terms of climate change. Gates and I can sometimes take
different approaches to climate change and that’s part of the reason why I found this book useful.
It concisely outlines what needs to be done in order to get to zero emissions by 2050.
Throughout the book Gates unpacks the five biggest emissions-causing sectors and explains how we can
minimize the greenhouse gas footprint of each one. There is even a whole chapter
about how we can get zero-emissions in the steel, cement, and plastics industry
by 2050! You can find out more about the book, and how we can all work together
to avoid a climate disaster using the link in the description below.
Hey everyone! Thanks for making it to the end. If you’ve already grabbed the book,
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Our Changing Climate stay afloat. Thanks for watching and I’ll see you next week!