After water, concrete is the most used material in the country. But concrete has also historically been harmful to our environment. According to a study published in 2019, the combination of calcination in the production of concrete, which in many places uses coal or natural gas as the main heat source, and the transportation of concrete are important reasons why concrete adds seven percent of the world’s greenhouse gas emissions per year worldwide.
“If the cement industry were a country, it would be the third largest emitter of greenhouse gases in the world,” said Eric Miller, director of energy policy for the Natural Resources Defense Council (NRDC) in New Jersey.
Concrete has been used for over 5,000 years, and during most of that time, its environmental impact has not changed much. But can the negative qualities of concrete become a thing of the past?
The term “low-carbon concrete” has entered the dictionary in recent years, part of a general change in all sectors of the construction industry to produce less carbon-intensive materials and also to reduce the carbon production of the construction processes themselves. Most of this is all about concrete, as it remains one of the most versatile, strongest, and affordable materials on Earth.
Low-carbon concrete examines the entire life cycle of the product. The heavy burden is in concrete production but also in transport and other areas.
Emission reductions in concrete can be achieve over the lifetime of the material, not just with one change. This includes component selection; production, transport, and construction processes; and post-construction maintenance, repair, and disposal or recycling.
First Movers and Legislation
One of the most important announcements at COP27 was that the concrete and cement industries joined First Movers. The First Movers Coalition is an initiative with 65 members (companies) committed to clean technology, and in 2022, concrete and cement will join aluminum, shipbuilding, steel, freight, and aviation. Big companies like GM and PepsiCo have joined First Movers.
At COP27, Shilpan Amin, senior vice president and president of GM International, noted that GM’s Tennessee plant has already begun using carbon capture technology on its electric vehicle. Mafalda Duarte, CEO of the Climate Investment Fund, noted that developing countries are the biggest industrial emitters, saying, “That’s why I was particularly happy that concrete and cement joined the First Movers Coalition because those products are in high demand in the developing world.”
First Movers is a private industrial consortium. But there has also been a lot of movement on the legislative side to promote the greenness of the concrete space. Some of the most notable are the climate investments that were included in the Inflation Reduction Act of 2022. This includes money for a new DOE project called the “Deployment of Advanced Industrial Facilities Program” that provides grants to companies to modernise and upgrade their functions. The “Buy Clean” initiative, which directs agencies to purchase green building materials for their projects, has also received a lot of attention.
According to Construction Dive, The bill’s funding includes the following:
- $2.15 billion to install low-carbon materials in buildings owned by the General Services Administration.
- $2 billion to replace low-carbon transportation subsidies and encourage the use of low-carbon materials in Federal Highway Administration projects.
- $250 million in grants and technical assistance to manufacturers to develop and standardise environmental product statements for building materials.
- $100 million to identify and label low-carbon materials and products for federally funded transportation and construction projects.
The author writes:
Although there are alternatives to cement, many are under development, and the traditional Portland mix is still viable. New federal funding allows contractors to use low-carbon materials at no additional cost and develop their green building expertise.
At a local level, states such as New Jersey are also encouraging the production of low-carbon concrete. The New Jersey Assembly recently passed legislation that would “provide a corporate income tax credit (CBT) and gross receipts tax credit (GIT) to concrete manufacturers who supply greenhouse gas reduction concrete for use in certain state-funded projects.”
“This bill is a smart and pragmatic step to reduce emissions from the construction industry while providing a competitive marketplace for New Jersey businesses,” said Ed Potosnak, executive director of the New Jersey League of Conservation Voters.
If we look at different states in the US, different low-carbon initiatives have been adopted. Colorado now has the Buy Clean Colorado Act, and New York has legislation creating a low-carbon procurement standard for concrete for public construction projects. Other legislation is being considered in California and other states.
On the new technology front, several breakthroughs are helping to make concrete production a much less carbon-intensive process.Carbon Cure’s technology embeds captured carbon dioxide into mixed concrete, where it turns into a mineral. It has been used in dozens of projects across the country, including at Amazon’s headquarters in Arlington, Virginia. Sublime Systems makes concrete that avoids the kiln entirely and uses an electrical process to transform the limestone at room temperature rather than the hot temperature of a kiln.
Another technology under investigation is biocementing, which uses microorganisms to create calcium carbonate, which gives concrete highly desirable bonding and strength properties.
In the near future, the most used technology will be carbon dioxide recovery, where carbon generated during production is captured, stored underground, and then put back into concrete to strengthen it or stored for other purposes.
Ars Technica recently published a detailed article on all kinds of new concrete technologies, such as kiln electrification, raw material switching, and alternative cements.
Thus, the concrete industry seems to be moving towards a low-carbon future at an early stage.