Preface. This is one of the best articles I have seen in years on concrete – its climate effects, how it is made, and ways that it could be made that would emit less carbon dioxide. Biomass does not scale up, hydrogen and electricity are not mentioned, and carbon sequestration is only done when subsidized by governments and captures very little CO2. In the U.S. the Trump administration cancelled most Biden-era “Buy Clean” initiatives for reducing CO₂ emissions in federal construction projects and another $1.6 billion to develop the market in sustainable concrete. What little CO2 is captured is valuable for the oil industry, one of the few that can use it, to produce even more oil by using CO2 to push it to the surface. Yet sequestration is the only way to reduce CO2 emissions for the foreseeable future. There are other materials that emit less carbon being experimented with, but the problem is, Portland Cement has proven itself for over 100 years and it will take decades or more for other options to convince builders to use alternatives. And it had better be cheaper.
There was no mention of using (renewable) electricity or hydrogen to replace fossil fuels in making cement.
Do read all of this excellent article if you can get past the paywall, so much is left out.
Alice Friedemann www.energyskeptic.com Recommended books author of “Life After Fossil Fuels: A Reality Check on Alternative Energy”, 2021, Springer; “When Trucks Stop Running: Energy and the Future of Transportation”, 2015, Springer, Barriers to Making Algal Biofuels, and “Crunch! Whole Grain Artisan Chips and Crackers”. Podcasts: Collapse Chronicles, Derrick Jensen, Practical Prepping, KunstlerCast 253, KunstlerCast278, Peak Prosperity , XX2 report
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Fishman TC (2026) The Spread of Concrete Is Damaging the Planet. Bloomberg Businessweek
The industrialized economy has sped up cement production and released hundreds of thousands of years of carbon the past 150 years and today produces 7% to 8% of all human-caused carbon emissions. Cement manufacture uses primarily fossil fuels to heat giant furnaces to 2,700F, to cook the carbon out of 4.5 billion tons of limestone a year.
About half of the world’s more than 1 trillion tons of human-made stuff is concrete (by mass), most made in the last 50 years. It takes 4 billion tons of cement to make 30 billion tons of concrete, enough for 3 to 4 tons for the 8.2+ billion of us on earth was made last year.
Quite a bit of coal, diesel, and other energy is used throughout the whole process. Many cement plants are next to thick-bedded limestone deposits where limestone chunks are blasted out and excavated by huge diggers to feed kilns. The stone is dumped into a powerful crusher that reduces the big pieces to chunks, which are then fed into a grinder that further reduces the stone to a finely powdered product called raw meal. That powder, mixed with some clay, is conveyed to the top of a steel pre-heater tower, where it travels through several stages designed to drive most of the CO₂ out of the rock. Most of this happens by spinning the stone and clay in a super hot cyclone that cooks it in stages until it goes inside a furnace called a calciner. The stone’s temperature reaches about 1,800F to release carbon dioxide. Unless captured, the gas heads into the air. This is the process that makes cement production so destructive to the environment. The remaining solid, calcium oxide, also known as quicklime, then travels again, to a giant, tubular rotary kiln that can be 300 feet long with heat up to 2,700F. Eventually small gray pellets called clinker emerge, the ingredient that makes Portland cement reactive. When the clinker is finely ground and mixed with gypsum, the Portland cement is finished. And even more energy to make and deliver to construction sites.
The vast majority of the world’s cement is Portland cement, a manufactured chemical powder that’s the crucial binding ingredient in most modern concrete. Portland cement is produced by more than 1,200 companies in 3,500 plants in 163 countries, with the top ten producing 40% of the global supply. Cement usually makes up 10% to 15% of the volume in a basic concrete mix. The rest is aggregate, mainly stones and sand. Water will be the binding that holds them together.
Cement and the concrete are central to modern living. Habitation, with over 90% of new homes made with it. Office buildings, factories, the floors in factories with the heavy machines on top to make motors, silverware, just about any product you can think of. Steel miles are anchored to concrete foundations, and a fifth of steel is used to reinforce concrete. Millions of miles of roads. 340,000 concrete bridges in the U.S. and over 800,000 in China. Canals, ports and airports. Nuclear power plants use 700,000 tons of concrete. The Hydropower infrastructure slated to be done in Tibet will use 300 million tons of concrete.. The municipal systems that deliver drinking water and remove sewage, the storm basis that would flood homes and leave toxins and trash. When concrete replaces dirt in poor regions, parasites and anemia drop in children about 80%, diarrhea in half.
It is the only affordable material with enough mass to hold large wind turbines in place against gravity, torque, and wind sheer with the turbines you see driving on roads using 1,000-2000 tons of concrete platforms.
The security and defense industries depend on concrete too. In 2016 the Modern War Institute at West Point identified concrete, not weapons or vehicles or computers, as the US Army’s most important strategic battle asset.
Jakarta and its 42 million people are sinking under the weight. About 90% is covered in cement and dropping 10-30 centimeters (4-11″) a year.
Decarbonizing cement is a hard problem for three main reasons. About 40% of the CO₂ comes from burning fuel, usually coal and a mix of industrial waste, to sustain high temperatures. Efficient furnaces and recycled fuels can reduce emissions, but the industry needs new supply chains to provide alternative fuels. Second, the other 60% of emissions are caused by the chemical transformation of the stone. Electricity is not used to cook cement, but the equipment (crushers, grinders, conveyors) use about 1.5% of global electricity. Third, the vast amount used in the world. Though steel emits 38 times more CO2 and glass 6 times more by volume. Even wood for construction can emit more CO2, especially if it is from a clear-cut forest, where the material left over will decay for 25 years and emit quite a bot of CO2 until new growth starts to grow.
Cement and concrete are not the same material. We build with concrete. Cement is just a constituent. In the U.S. 80% is ready-mix that can be poured wet produce in several acres of industrial yards. When cement and concrete materials (sand, stone, chemicals, coloring) and water are poured into concrete mixer trucks, the concrete begins harden inside the trucks’ barrels as they travel to their destinations. On its way to becoming rock-hard, concrete is highly perishable. It takes about 90 minutes of churning in a truck before hydration goes too far and concrete becomes too stiff to mold, smooth or push into place. So production must be very local. In big cities the dispatch centers look like air traffic control rooms, as 40-ton trucks are timed and steered through packed streets and around road construction and bridges unfit to carry their weight. There are 7,000 ready-mix batch plants in the US.
Half of the world’s concrete is made from bags of cement combined with other ingredients on-site, about 36 billion 110-pound bags of cement annually. Much is used in small projects in emerging economies, such as family home construction. There are roughly 280 million construction workers in the world, and almost all construction involves concrete. The International Finance Corporation estimates that cement and concrete’s “long and diverse supply chain” makes up 5.4% of all the world’s goods and services and employs about 1 in 13 workers.
Concrete formulas that rely heavily on Portland cement have track records that reach back more than 100 years. It’s tough to simulate in a model or lab 100 years of stress and environmental wear and tear on structures made with new, radically innovative materials. Except for devastation from wars and natural disasters, structural failure of concrete buildings built to code is statistically rare. New materials must prove themselves against this record.
With half a megaton captured here and a megaton captured there, carbon capture can’t yet promise carbon reductions close to the scale of the cement industry’s 1.6 gigatons of yearly emissions. (A gigaton is 1,000 megatons.) And carbon capture still needs huge subsidies, which makes the technology vulnerable to fickle politics. Last year the US Department of Energy pulled the plug on a $500 million grant Joe Biden’s administration had signaled it would fund for carbon capture at Heidelberg’s cement plant in Indiana. In November the Swedish Energy Agency refused to commit $870 million to a long-planned project.
The other big hope is biochar, which does not scale up. It is charcoal made from heating plant waste in the absence of oxygen. Leaves, sticks, tree bark, corncobs, manure and more can be used. Because plants absorb CO₂ through photosynthesis as they grow, biochar made from plant material contains carbon. Making biochar usuallyreleases some CO₂, but as much as 10 times more carbon is sequestered. Lock biochar up in the mass of concrete and the carbon is entombed too. It also makes concrete stronger, more durable and more resistant to the kind of cracking that afflicts concrete reinforced with steel. But there isn’t enough of it available. And very little infrastructure to move and process it.
Architecture 2030 estimates that by 2060 the world will have constructed enough new buildings to add 2.6 trillion square feet of floor space. That’s double the floor area of all buildings that exist now. The UN Environment Programme estimates the world’s cities will be home to 2.5 billion additional inhabitants by 2050. Extrapolating from that figure, engineering software maker Autodesk Inc. has calculated that “the construction industry will need to build an average of 13,000 buildings every day and construct 700,000 miles of roads and nearly 90,000 bridges every year by 2050. More than half the mass of what’s coming will likely be concrete.
And that doesn’t include the cement and concrete needed to fix what the world has already built.