The cement industry has attempting to become carbon neutral by 2050. But production of green cement relies on technologies that are still years away, as a factory in Rüdersdorf, Germany, is showing.
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00:00You take this common raw material, limestone, grind it down, mix it with some rocks, heat
00:07it up to the temperature of molten lava, then let it cool, grind it again, and what do you
00:13have?
00:14Well, that's the basic recipe for cement.
00:16Sounds relatively simple, right?
00:19But there is a major complication.
00:21The cement industry is a massive CO2 emitter.
00:24The business wants to go carbon neutral, so is that even possible?
00:33Roads and highways are made with cement.
00:35High-rise skyscrapers, cement.
00:37The building where you're watching this video right now, somewhere there's cement.
00:42The cement industry has quietly doubled its emissions in the last 20 years.
00:46The main reason?
00:47The amount of this material needed in both industrialized and developing countries.
01:06The cement industry is one of the world's most carbon intensive.
01:10If it were a country, it would be the third largest carbon dioxide emitter on the planet.
01:15And its use has exploded in recent decades, led by far by China.
01:21That country so outpaces the rest of the world's cement consumption that in 2020, it used nearly
01:2610 times as much cement as its closest competitor, India, around 2.4 billion tons compared to
01:32290 million.
01:35And use is expected to continue to grow globally.
01:38Worth nearly $327 billion in 2021, cement production is anticipated to increase dramatically
01:46before the end of this decade.
01:50Just outside of the German capital, Berlin, Mexican cement giant Cemex is trialing new
01:55solutions to combat some of the problems plaguing the industry.
02:01It's one of several flagship factories around the world where Cemex is trying to tackle
02:05the massive problems.
02:08This one in the European Union.
02:11After growth of the industry comes heat.
02:13Back to our recipe from the beginning, limestone and these other rocks we mentioned need to
02:18be heated to the temperature of molten lava.
02:21That's not an exaggeration.
02:23Huge ovens known as kilns like this one need to reach temperatures of over 1400 degrees
02:28Celsius.
02:30We're standing dozens of meters above the Cemex kiln, and you can still feel the heat
02:34and see the air shimmer.
02:37We don't need to have that temperature just for a couple of minutes or an hour.
02:41We need to have that temperature 24-7.
02:45Whole day long, whole week long.
02:48Keeping a kiln at this temperature, it's one big energy suck, and it's mostly being powered
02:53by fossil fuels, think coal, oil and natural gas.
02:57And a massive part of the industry's emissions come from the energy to run a cement factory,
03:02which includes the kiln.
03:06Now you might be wondering, why not just use solar panels like these or other renewables
03:11to heat that kiln that needs so much energy?
03:14Well, simply put, renewable energy can't generate the kinds of heat needed, especially not on
03:21an industrial scale.
03:23That's how Robbie Andrew, a senior researcher at the Cicero Center for International Climate
03:27Research explained it.
03:29He's been following how industry emits CO2.
03:32Traditionally, they kind of topped out around 100 degrees or something like that.
03:37So there are new developments there getting up to 400 or 500, which is kind of the middle
03:42range for industrial heat usage.
03:44But in cement manufacturing, we're talking about over 1400 degrees Celsius.
03:49So it's really high temperatures.
03:52Rather than relying just on fossil fuels, Cemex has been increasing its mix of so-called
03:57alternative fuels.
04:00In 2022, these fuels made up approximately 35% of the energy mix used to heat that kiln.
04:07We're talking burning waste plastics that would otherwise have ended up in landfills,
04:11dried sludge from sewage and industrial management plants.
04:14Yes, that can mean human waste.
04:17And biomass, essentially shredded wood that is at least on paper, made carbon neutral
04:22by the planting of replacement trees.
04:26Right now, there are test projects under development that could let renewables play
04:30a larger part in cement production, like this concentrated solar energy field, which uses
04:35massive mirrors to really focus the sun's rays and could one day be used to heat kilns
04:40to those super high temperatures.
04:42But it's fair to say that they're not quite there yet, and until the technology is ready
04:46to use, it could take some time.
04:52Of course, the whole reason that companies need so much energy to create so much heat
04:57is because of this guy, limestone.
05:00Chemically known as calcium carbonate, when heated, a limestone molecule separates, leaving
05:05behind calcium oxide, or CaO, which is a great binding agent in cement, but also left behind
05:13carbon dioxide, not so useful and a big contributor to global warming.
05:18In fact, at least half of CO2 from cement manufacturing comes from this so-called calcination
05:23process.
05:24That is fundamental because it means that you can't simply move away from fossil fuels.
05:32Joanna Lina works for the climate change think tank, E3G, where she leads the industry transition
05:37and trade program.
05:38You can't simply use a more energy efficient kiln, you need to actually either fundamentally
05:44change the kind of chemistry of how you're producing cement, move towards different raw
05:48materials, or you need to capture that carbon and store it.
05:53Reducing the amount of this limestone mixture in a cement recipe has been a decades-long
05:57goal of the cement industry.
05:59Not only does less of the mixture, also known as clinker, mean less energy to cook that
06:03rocky mixture, but it also means less leftover CO2.
06:08New recipes for greener cement fall into two main categories, recycled materials and ingredient
06:13replacement.
06:14By recycling materials, there's two theoretical benefits, a circular economy and less energy
06:19used because you don't have to cook that virgin limestone again.
06:24So what kind of materials could be recycled?
06:27In some cases, old concrete from demolished buildings can be ground up and replace a certain
06:32percentage of the essential ingredients that we mentioned at the beginning to make cement.
06:37Hesam Azari Jafari works for the Concrete Sustainability Hub at MIT and says there's
06:43a lot of hesitation about this technique.
06:45It can be used and, you know, replace the virgin aggregates that we are using for concrete
06:56construction.
06:57There's a lot of, you know, precautions with use of this kind of recycled materials to
07:02make sure that it doesn't compromise the performance of the concrete mixture as well.
07:09What type of concrete, and so cement, is needed is dictated by how much pressure or
07:14weight it has to hold or how durable to the elements it has to be.
07:19Think of a load-bearing pillar versus a road, different functions and different exposures
07:23to the elements.
07:24So you need to make sure the recipe you're using makes a cement that is up to the job.
07:31Using recycled materials prevents emissions from machinery that would otherwise be used
07:35to mine for new resources.
07:38But carbon dioxide is still emitted when knocking down and transporting old building pieces.
07:44We have to classify it, we have to crush it, sort it again, and then transport it again
07:50to the next concrete production facility.
07:54That's especially true if buildings aren't properly labeled with the materials that they're
07:58made of.
08:00So sorting the debris has the potential to be more carbon intensive than digging fresh
08:04materials out of the ground.
08:06So what about the other option?
08:08What could limestone be replaced with?
08:11There are a few materials being considered to replace limestone, at least in part.
08:15One is iron slag, the other is calcium silicate.
08:18Whereas limestone has carbon and oxygen in it, which you try to strip out to get your
08:22calcium oxide, the calcium silicate doesn't have the carbon in it.
08:27So that when you break it down to get the calcium that you want, you don't release CO2.
08:32The recipes are still under development on how exactly calcium silicate or other rocks
08:37can replace limestone.
08:40Testing is still needed to make sure that a recipe made with any substitute will stand
08:44the test of time.
08:46Customers want assurances that buildings will stay standing and age well.
08:52The truth is that even if the strategies we've already mentioned work, producing cement will
08:57still emit a lot of CO2.
08:59So the industry has another solution, and a controversial one.
09:03Carbon Capture and Storage, or CCS.
09:06This essentially means that right when a carbon dioxide molecule would be released from the
09:11source, it's chemically captured, meaning it's not released into the atmosphere.
09:16Proponents say CCS is essential if cement is to make a significant dent in its emissions.
09:24CEMEX plans to capture the majority of its emissions at the facility near Berlin through
09:29CCS by 2030.
09:30I wouldn't say easy.
09:32It's expensive and complicated, but it's doable.
09:35It's a proven technology.
09:37The technology is decades old, but it has yet to be used at scale.
09:41Countries like Germany have strict storage regulations, even as projects like this one
09:45here in Norway are hoping to soon accept CO2 from industrial sites.
09:50But critics argue cement business plans that include carbon capture and storage don't make
09:55economic sense.
09:56They say that the plans that include CCS would dramatically increase the price.
10:02And it could simply allow high-carbon industries to keep on emitting.
10:10Big shifts within the construction industry are on the horizon.
10:13The European Union, for example, is discussing stricter carbon emission standards from the
10:19And while some customers want the green shine that comes with lower-carbon cement, many
10:23still want the cheapest and most reliable options.
10:27So can cement be made with fewer emissions?
10:30Yes, it's already happening, to some extent.
10:33But technology needs to accelerate, and companies need to be investing in that technology to
10:37help get them there.
10:38This is especially true in regions that are expected to rapidly develop in the coming
10:42decades.
10:45And as these countries continue to build roads, hospitals and other infrastructure, there
10:50are options.
10:53Carbon capture could help solve the process emissions problem that comes with limestone,
10:58but the technology and regulatory frameworks aren't in place yet.
11:03Improving green energy technology is a possibility for replacing the massive amounts of energy
11:08needed to heat kilns and other parts of the manufacturing process, and of course, recycling
11:13materials and building things to last are also critical to long-term carbon savings.
11:20This new recognition that we need to reduce global emissions from net zero by 2050 is
11:25a real spur to drive that further.
11:27But it's hard for this industry.
11:29The global industry has a roadmap for reducing emissions.
11:34They're very clear that that requires all sorts of changes to the market, the recognition
11:38of value. It requires all sorts of government interventions.
11:43And it requires technology development.
11:46Do you think the cement industry will stay true to these promises and goals?
11:50Tell us in the comments below.
11:52And if you're looking for more business solutions to the climate crisis, check out the
11:55Transforming Business playlist.