The third largest country?


What country is synonymous with economic development, rampant with highways, tall buildings, bridges and dams; and is the third largest emitter of CO2 on earth?

Maybe the photo gave it awy. It’s not a country at all—it’s concrete.

I’ve come to love and appreciate this age-old, humble and grand material. And beautiful: the Roman Colosseum and the Pantheon, Fallingwater, the Sydney Opera House, and Sagrada Familia. From Le Corbusier to Zaha Hadid; the ancients to the modernists. The Grand Coulee Dam. The tallest buildings in the world. The Panama Canal. A 125-foot-tall statue of Jesus in Brazil. (Stop me now—I could go on.)

My point is: it’s the most practical, cost effective, most widely-used, and (potentially) handsome structural material in the world—and it’s helping to kill the planet.

What is it exactly? Concrete is a mix of cement, aggregates like sand and gravel, and water, and in structures it's generally reinforced with steel. Cement is the lime-based, kiln-baked binder, and that’s where the problem lies. The kilning (technically, the calcination process) is the source of about 8% of the world's carbon dioxide emissions (says Chatham House, a British think tank). If the cement industry were a country, it would be the third largest emitter in the world—behind China and the U.S. It contributes more CO2 than aviation fuel (2.5%) and it’s not far behind the global agriculture business (12%).

Just to convey the scale of this problem: worldwide cement production has increased more than 30x since 1950, and almost 4x just since 1990. Roughly 0.25% of the total energy consumed in the U.S. goes to cement production, according to the U.S. Energy Information Administration. China now uses nearly half the world’s concrete; it used more cement between 2011 and 2013 than the U.S. did in the entire 20th Century. This is mainly driven by rapid modernization both in and by China, especially in Southeast Asia and Sub-Saharan Africa.

India and Indonesia are just entering their concrete-intensive phase of development. Over the next 40 years, the newly built floor area in the world is expected to double. By one ingenious calculation, we likely have passed the point where concrete outweighs the combined carbon mass of every tree, bush and plant on planet earth. Our built environment is overwhelming our natural habitat. All the plastic produced over the past 60 years amounts to 8 billion tons; the cement industry pumps out more than that every two years, yet concrete gets very little public criticism.

Not only that, concrete is a thirsty beast, gulping down nearly 1/10th of the world’s industrial water use. Naturally, this can stress drinking water and irrigation supply, because 75% of this usage is in drought and water-strained regions. In urban areas, concrete also contributes to the heat-island effect by absorbing the sun’s warmth, trapping the gases from car exhausts and air-conditioners (although not as much as asphalt).

So there’s a LOT of bad news. There’s a small bit of good news too, but like most sustainable processes that are essential to turning around global climate change, it requires us to change the way we behave. And that seems damn near impossible in this world.

To reduce emissions, experts push increased use of renewables in production, improved energy efficiency (CO2 reduction), and more recycled substitutes for “clinker” (the end product of kilning, which is then ground into cement powder). These steps are relatively easy and even cost-saving using current cement production infrastructure. But the most important change needed is the adoption of carbon capture and storage technology. And this is expensive. So, while some are testing it, the cement industry hasn’t adopted it on a commercial scale.

There are sustainability-conscious companies in the industry, representing about 35% of cement production, which are actively working to make needed changes. Leaders were in Poland in 2018 for the UN climate change conference and published a Sustainability Charter, defining how the industry must meet the requirements of the Paris agreement. To address the challenge, annual cement emissions overall will need to fall by at least 16% by 2030.

Some point to improvements in the energy-efficiency of new cement plants burning waste materials instead of fossil fuels, which have caused average CO2 emissions per ton of output fall by 18 percent over the last few decades (again per the independent Chatham House report). But if the industry has any hope of meeting its commitments to the 2015 Paris Agreement, it will need to overhaul the cement-making process itself, not just reduce its use of fossil fuels.

All of which stimulates my consciousness about this material I’ve been joyfully working with. I’ve been wondering what I can and should be doing to help us imagine a better way. Recently I visited a Seattle cement plant to learn more about the industrial process and sustainable practices. It was an eye-opener; more to come...

Image credit: lib.Berkeley.edu

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