Photo of Blue Circle Southern Cement factory near New Berrima, New South Wales, Australia, by WikiMedia Common contributor AYArktos

Portland cement is named for the area in England where it was first made almost three-hundred years ago, and is the standard ingredient used to create concrete around the world. Despite being a very useful building material that can be applied in a variety of ways without expensive technology, cement production is associated with carbon dioxide emissions, primarily from when the original limestone is decarbonized and from the massive amounts of fuel needed to fire up the kilns to make cement. Robert Hutchinson of the Rocky Mountain Institute writes an informative piece for GreenBiz on how the industry might change, and why:

The toughest climate challenges involve large global industries, with no good substitutes. One of these produces the material literally under our feet — concrete. Every year, each of us in the U.S. uses about one-third of a ton. Fast-growing developing countries use far more. Globally we produce over 4 billion metric tons of Portland cement per year — the key ingredient in concrete and responsible for the majority of its CO2 footprint — driving over 5 percent of total anthropomorphic CO2.

Rocky Mountain Institute’s research on the topic reveals that, to have a chance of significantly shrinking the industry footprint and meeting our Paris Agreement goals, revolutionary thinking and significant disruption is needed — a Tesla for cement, as it were. The industry-sanctioned traditional levers are not enough. And the new cement has to be really cheap. We have found three important opportunities that might work.

Why cement and concrete are huge

Finding a new, broadly applicable solution will not be easy, because the world needs so much concrete. It is the most flexible, cheap and universally used building material on the planet. The only thing we use more of globally is water.

Total Portland cement volume — making up about 20 percent of concrete by weight (the other main ingredients are sand, aggregate and water) — has more than tripled in the last 20 years (a growth rate of close to 6 percent per year), most of the growth being in China.

As China slows, another wave of countries such as India, Turkey and Indonesia may take over as growth drivers, plus the U.S. if needed infrastructure rebuilding takes off. Global cement production growth may stay in the 2 to 4 percent range for a long time.

New plants being built in developing countries are much more efficient than the oldest plants anywhere — and much better than the average in the U.S. (India’s national cement industry average CO2 emissions rate is 25 percent lower than that of the U.S.) However, the total improvements that the best companies are making — about 0.5 percent per year over the last few years — cannot come close to counterbalancing even their own growth. And not all players are really trying.

Standard Portland cement cannot be made without releasing significant amounts of CO2, which is done in two ways: through burning fuel to produce the very high kiln temperatures needed; and through a calcining chemical reaction that occurs when the limestone is heated. At the most efficient plants, 60 percent or more of CO2 released might be from this unavoidable chemical reaction.

Although other natural or waste materials such as rice hulls, limestone, blast furnace slag and some kinds of fly ash can be partially substituted for Portland cement, the very standardization of Portland cement into a small and specific set of high-performing global products has helped it become so dominant. This standardization is a huge barrier for any specific substitute.

What the industry is doing today

Like any industry that has been around a long time, some well-established levers make it more efficient and emit less. The problem is, they are voluntary, coordinated by the Cement Sustainability Initiative (CSI) and do not go far enough to do more than slightly slow the growth of industry CO2 emissions. The CSI recommends the following to its members and the global cement industry:

• Plants and transportation of raw materials and products can be made more efficient, both thermally and electrically, and the worst plants can be shut down.
• Plants can burn organic waste or biomass to heat kilns (as in Brazil, which may lead the world in low CO2 emissions related to cement production).
• Supplementary cementitious materials (SCMs) such as fly ash can be used instead of some — and often quite a lot — of the Portland cement.
• Alternative lower carbon chemistries such as magnesium oxide-based cement, using special additives or simply more judicious and use-specific mixing can reduce the amount of Portland required to achieve specific properties of a concrete.

All of these are actively underway in some of the world’s cement markets. Leading players have targets in place for emissions intensity and use all these levers. However, progress has not been and likely never can be fast enough. This is partly because the industry focuses first and foremost on reliability and product quality, which makes introducing any change challenging, slow and costly.

There must be proof that new approaches work. What’s more, the industry is very asset-intensive, having a lot of money sunk into plants and equipment compared with its revenues and profits. Changing plants is expensive, and industry cash flows are not enough to make those changes quickly and still satisfy investors’ or government owners’ cost of capital.

Change is also slow because most new plants are built in the developing world — typically not a good place to try innovative approaches given the on-site expertise needed to ensure something new or different actually works. And finally, industry dynamics sometimes have kept things slow.

For instance, few companies want to invest in higher efficiency and “greener” cement if cheaper “dirty” cement can be imported from another country without being blocked or taxed. Such “carbon leakage” is a particular problem in Europe due to its proximity to North Africa and the Middle East, which have no regulations and can ship product cheaply across the Mediterranean.

Read the concluding sections of Hutchinson’s piece, including how the industry can become more sustainable, here.