Opinion: Cement doesn't have to be a big part of the carbon problem


In 2014, hundreds of Angelenos gathered downtown to watch more than 2,000 trucks pour concrete into a gaping hole. During that event, Los Angeles established a world record: 80 million pounds of concrete were placed for 18 hours straight to form the foundation of the Wilshire Grand Center, which now rises 73 stories above the city.

This material that has been used for thousands of years, which formed the Colosseum and the Pantheon, has become indispensable. Is he most consumed material of human origin on earth. It is also one of society's largest sources of greenhouse gas emissions.

Globally, the manufacture of cement, which joins sand and rock to form concrete, emits 8% of carbon dioxide pollution into the atmosphere, contributing to climate change that is causing wildfires, hurricanes and record heat waves. Cement and concrete manufacturing. emits as much carbon dioxide as India.

We can't stop building the homes, factories and roads we depend on, but we can and must stop rampant emissions from cement. Fortunately, new technologies are beginning to show the way forward, and even promise that cement production could one day extract carbon from the atmosphere and become part of the solution to global warming.

In cement manufacturing, limestone and other ingredients are added to a kiln. In the current standard process, fossil fuels are burned to heat the furnace, emitting carbon dioxide. The heat breaks down the limestone, releasing carbon trapped within the rock and emitting more carbon dioxide.

This makes cement a massive source of greenhouse gas emissions that accelerate climate change, and its use is expected to increase. continue increasing until 2050driven by the world's growing population, urbanization, wealth and infrastructure needs.

Here in California we produce more cement than any other state except Texas. In 2022, our state's cement plants emitted more than 9 million metric tons of carbon dioxide, equivalent to the emissions of 2 million cars and SUVs or 22 gas-fired power plants. This makes our state an excellent laboratory for finding solutions.

Electrically heated cement kilns and alternatives to limestone could dramatically reduce climate pollution. For example, an Oakland-based company markets cement made from carbon free calcium silicate rockwhich does not emit carbon dioxide when processed in an oven.

By combining clean heat with carbon-free minerals or equipment to capture carbon emissions from the breakdown of limestone, cement manufacturing could become carbon neutral by 2045. That's a great first step, but the innovations that are underway happening today could take us beyond carbon neutrality.

Once concrete is made, it gradually absorbs carbon dioxide from the atmosphere in a process called carbonation. With today's common ingredients and techniques, making cement produces more emissions than the material can subsequently absorb, so each new ton of cement worsens climate change. But if cement kilns are heated with clean electricity and emissions from mineral decomposition are avoided or stored underground, then simply pouring concrete would remove carbon pollution from the air. New construction would help repair our climate.

This will not happen on its own. Governments will have to implement smart policies to incentivize clean cement manufacturing. California is taking the lead, but the race is not over.

In 2021, Governor Gavin Newsom signed Senate Bill 596requiring the state's cement producers to achieve net zero greenhouse gas emissions by 2045. Then, last August, the California Building Standards Commission established limits on emissions derived from the manufacturing of materials used in large commercial and school buildings. We are the first state in the country to consider these emissions “built-in” into building codes.

Next, California should do more to help cement manufacturers reach their net-zero emissions goal. The 2017 Buy the Clean California Act ordered that state infrastructure projects prioritize steel, glass and insulation made with low-emission processes. This provides a protected market in which low-carbon manufacturers can sell products without competition from dirty materials, helping to scale up clean manufacturing and reduce its costs.

Unfortunately, concrete was removed of the bill before it became law, which at the time seemed designed to prevent the industry from being regulated. In retrospect, his exclusion denied cement and concrete manufacturers a lucrative market that could have paid above-market rates to help them commercialize clean cement technology. The state Legislature should amend the statute to include cement and concrete, as well as other important construction materials, such as aluminum.

Additionally, the Building Standards Commission can expand the market for clean cement by expanding the limits on embodied emissions for other types of buildings. And support clean cement used in projects funded by the California Infrastructure and Economic Development Bank could provide incentives in a way that does not worsen California's budget deficit.

Cement is an ancient invention that remains crucial to the modern world. But producing it using outdated methods is taking a terrible toll on our climate. Fortunately, innovative cement technologies can build stronger societies and simultaneously fight climate change by removing carbon dioxide from the atmosphere.

One of today's biggest climate threats could become the foundation of a sustainable future.

Jeffrey Risman is senior industry program director at Energy Innovation, an energy and climate policy research firm in San Francisco. The book of him”Zero carbon industry”will be published on February 27.

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