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Humans use around 90 billion metric tons of materials every year, creating about ⅓ of total global greenhouse gas emissions. Which materials produce the most emissions? You might be surprised.
In this episode of TILclimate (Today I Learned: Climate), MIT professor Elsa Olivetti joins host Laur Hesse Fisher to talk about materials, or as Prof. Olivetti calls it, “the study of stuff”. Prof. Olivetti explains where these emissions come from and how to reduce emissions and waste in our manufacturing.
Prof. Olivetti is the Atlantic Richfield Associate Professor of Energy Studies in the Material Science and Engineering Department at MIT. Prof. Olivetti focuses her research on developing strategies to make materials and manufacturing more efficient, inexpensive, and environmentally-friendly.
For other climate explanations, check out: www.tilclimate.mit.edu.
Laur Hesse Fisher, Host and Producer
David Lishansky, Editor and Producer
Cecelia Bolon, Student Production Assistant
Ruby Wincele, Student Researcher
Music by Blue Dot Sessions
Artwork by Aaron Krol
Special thanks to Tom Kiley and Laura Howells.
Produced by the MIT Environmental Solutions Initiative at the Massachusetts Institute of Technology.
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Elsa Olivetti: [00:00:00] Just the quantity of materials is kind of astounding. I think that's partly what's tricky about any of these conversations around CO2 or you know materials use is that the numbers are huge and how do you relate them to anything that feels more concrete to us is difficult.
Laur Hesse Fisher: [00:00:16] Thanks for joining us on Today I Learned Climate, where you learn about climate change from real scientists. I'm your host Laur Hesse Fisher. Today I asked an MIT Professor about stuff: the materials that companies use to build our infrastructure and that we use in our everyday lives.
Elsa Olivetti: [00:00:35] My name is Elsa Olivetti. I'm the associate professor... Wait no. That's not right. I'm the the Atlantic Richfield Associate Professor of Energy Studies. I work in the department of Material Science and Engineering here at MIT.
Laur Hesse Fisher: [00:00:50] Professor Olivetti studies the impact of materials on our environment and how we can lighten the load.
Elsa Olivetti: [00:00:56] I was always interested in the broader implications of materials and how they fit into the systems and society, you know how we interact with them as people.
So for example, if we were to increase the electrification of the vehicle fleet dramatically there would be a significant increase in demand for the derivatives of cobalt. So trying to understand kind of the match between the supply of those materials and the demand for those materials.
Laur Hesse Fisher: [00:01:19] And some of Professor Olivetti's work is at the lab bench where she and her students try to better understand the chemical makeup of materials.
This helps them explore how these materials can be used reused or recycled.
Elsa Olivetti: [00:01:32] A lot of times the way we currently dispose of those materials -- waste materials from different industries -- is either just in a landfill or as volume that would go into roads. And so that's that's a use, but it's not a particularly high value use, right?
So in order to understand how we might make use of those waste materials in higher value or more environmentally beneficial materials, we need to understand what's in there, what is their chemical composition, how reactive might they be under certain conditions...
Laur Hesse Fisher: [00:01:59] And the innovations that come from this research can be simple, yet pretty impactful.
Elsa Olivetti: [00:02:05] So one when thing we make that's pretty easy to wrap your head around is a brick right? So you.. But it's a brick that's fired at pretty high temperatures. So it's you know, we make that, the processing of that is upwards of a thousand degrees Celsius, but if we're able to make use of the chemistry, you know, we can do that instead of 30 degrees C.
Laur Hesse Fisher: [00:02:24] That's only 86 degrees Fahrenheit
Elsa Olivetti: [00:02:26] Or a warm day in India, which is where the project is based, so that works out. And so in order to do that, in order to enable that reaction to happen at 30 C, we need to understand how durable is that over time, is there going to be an issue if it's, you know in the monsoon season if there's a lot of water that's taken into those materials, those bricks. You know, we can develop a really fancy technology, but if we don't understand what the local context is then maybe that's not useful.
Laur Hesse Fisher: [00:02:53] So I've heard you share that materials and manufacturing make up about one-third of carbon emissions globally. Can you break that down for us? So what's causing these emissions?
Elsa Olivetti: [00:03:03] The majority of it is steel and cement. 25 to 30 percent is steel, and about 20% is cement. You know, aluminum and paper, and plastic are all about five percent, five to ten percent depending a little bit of how you group these things, but there are these big contributors and so it's just important not to forget that: that from a mass perspective that focusing on innovations in steel and cement are always useful. So if you want to move the needle on CO2 emissions when it comes to materials, you have to think about those those two.
Laur Hesse Fisher: [00:03:33] After water concrete, which is made from cement, is the second most widely used material on the planet. Think of all of our pavement all of our factories and buildings, Bridges and highways.
Elsa Olivetti: [00:03:47] To give a little bit of a scale, just the quantity of materials is kind of astounding. So it's I think it's 90 billion metric tons per year of materials.
And so cement is you know upwards of maybe between 3 and 4 billion metric tons per year.
Laur Hesse Fisher: [00:04:05] How can I even start thinking about billions of metric tons? Do you have any way that I can visualize that or try to understand that?
Elsa Olivetti: [00:04:14] Probably not. I mean, I don't know we--with it with the project in India we were thinking about the waste generation that was happening per day in these facilities in terms of elephants. Like you could sort of think about an elephant...
Laur Hesse Fisher: [00:04:26] How much does an elephant weigh?
Elsa Olivetti: [00:04:27] 2 to 5 tons...
Laur Hesse Fisher: [00:04:30] Okay. All right. So that's still billions of elephants.
Elsa Olivetti: [00:04:34] Yeah
Laur Hesse Fisher: [00:04:34] I can barely imagine a thousand elephants, let alone a billion elephants. That's just such a huge
Elsa Olivetti: [00:04:41] Yeah
Laur Hesse Fisher: [00:04:41] number.
Elsa Olivetti: [00:04:43] I think that's partly what's tricky about any of these conversations around CO2 or you know materials use is that you know, the numbers are huge and how do you relate them to you know to anything that you know feels more concrete to us? It's difficult.
We're on the orders of billions of metric tons. It's still growing, right? We're still building infrastructure. That's why trying to move the needle on CO2 emissions in that is hard because we're still making a lot.
Laur Hesse Fisher: [00:05:10] Okay, so steel and cement make up a majority of where CO2 emissions come from in materials and manufacturing.
But why what causes those emissions?
Elsa Olivetti: [00:05:20] We're talking about CO2 emissions. The majority is in two places really. It's, you know, the energy to run the factories, you know, the CO2 emitted because of energy generation and the CO2 that comes from the chemical reaction.
Laur Hesse Fisher: [00:05:34] To build this out a little so factories use a lot of electricity to make cement and steel, and the amount of CO2 associated with that depends on what kind of fuel is used to make the electricity.
So like you and your house may use as much electricity as I do in my house, but if you get your electricity from wind or solar, and if I get my electricity from coal or gas, then running the lights that your house will contribute a lot less CO2. So in addition to that, making cement requires chemical reactions that emit CO2 and other greenhouse gases. Kind of like how the chemical reaction that happens in your car's engine create CO2.
So when we look at the CO2 released by making steel and cement, we need to look at how much electricity is being used and how that electricity is being generated, as well as how many emissions are released from the actual chemical reactions.
Elsa Olivetti: [00:06:31] That depends on what grid you're using, but it's roughly 50/50 between the energy used and then the kind of reaction of the processing associated with that material.
Laur Hesse Fisher: [00:06:40] So as you're looking at something like steel and cement what are the efforts that are underway either by your team or other colleagues that you know about to reduce the impact of this?
Elsa Olivetti: [00:06:52] Trying to use supplemental cementitious materials, where we're using a little bit of something in place of a little bit of something else.
Laur Hesse Fisher: [00:07:00] So this is using a different ingredient for cement that actually reduces CO2 because there's not as much of a chemical reaction. And because this new ingredient is a waste product from another industry, this also means you're giving that waste and economic value and a second life. Another solution is to use a different material all together.
Elsa Olivetti: [00:07:23] Cars is a great example, right? The material that we're making our cars out of. So aluminum requires more energy to make, more electricity to make, but it'll use less CO2 over time depending on how long we drive the car.
Laur Hesse Fisher: [00:07:35] That's interesting, it would use less CO2 than something like steel, which is heavier, because the car actually takes less gas to run.
Elsa Olivetti: [00:07:42] Yeah.
Laur Hesse Fisher: [00:07:43] So scientists look at both the CO2 emissions from mining and making material and also the emissions that may come with using the material, like making cars lighter and more fuel efficient. But what happens when stuff is done being used? Well, how easily something can be reused or recycled is largely dependent on how it's made.
Elsa Olivetti: [00:08:08] As technology has become, you know, amazing and advanced we increasingly make things more complicated, meaning more elements, which you know, there's more different kinds of stuff in them, which makes it more difficult to manage at end of life. So we sometimes make the joke that you carry the periodic table in your pocket, in your cell phone, and it's not that much of an exaggeration because of the increasing complexity of that, and that's true not just for electronics, but alloys and jet engines and you know, the way we have become more and more advanced is typically adding more complexity to them.
So I think that that's just another tension in terms of the quantity is also the complexity and trying to manage that as much as we can is the challenge we face.
Laur Hesse Fisher: [00:09:01] Steel cement and reusing materials are huge areas for innovation, and many different groups at MIT and around the world are tackling them. To see some new and pretty creative solutions, check out our show notes on tilclimate.mit.edu. That's tilclimate.mit.edu.
What do you want to know about climate change? Do you still have a question from this episode or one of our previous episodes? Let us know. Tweet your question with the hashtag #TILclimate, or sending an email to climate at mit.edu.
Thanks so much to Professor Elsa Olivetti for speaking with us and to you for tuning in to Today I Learned Climate. I'm Laur Hesse Fisher from the MIT Environmental Solutions Initiative. See you next time.
Read more about:
Prof. Olivetti’s projects:
Solutions developed at MIT & beyond:
A company founded by MIT alumni recently developed a new way to process steel, that could cut 5% of CO2 emissions
MIT students found that plastic from disposable water bottles can be used to make concrete that is up to 15% stronger (MIT News)
An MIT Climate CoLab winner designed concrete made from hemp
An MIT research group focused on sustainable concrete
Our modern world uses many different materials, often complexly constructed and difficult to recycle. Students investigate the elements in a smartphone and innovations in cement and steel. They also consider the challenge of communicating about large and complex numbers.