The cement production process emits a large amount of carbon dioxide. However, the demand for housing and public buildings in most major cities around the world continues to grow. This trend is contrary to the international consensus on reducing greenhouse gas emissions. How to reduce carbon dioxide emissions in the cement industry has become a focus of attention from all walks of life.
Startup Synhelion uses photovoltaics to produce cement clinker. Mirrors concentrate solar radiation onto Synhelion's solar tower receiver. Image source: Synhelion
According to McKinsey, a US management consulting firm, approximately 7% of global anthropogenic carbon emissions come from the cement industry, making it one of the heaviest emitters of carbon within heavy industry. Claude Loréa, Head of Cement Innovation and Environmental, Social, and Governance (ESG) at the Global Cement and Concrete Association (GCCA), stated that even by 2050, three-quarters of the world's public infrastructure will still be waiting to be built, and cement consumption is expected to continue to grow.
The Wall Street Journal explains that Portland Cement is the most widely used cement in various countries. During the production process, raw materials such as clay and limestone are first ground into raw materials. The raw materials are then placed in a cement kiln at a high temperature of approximately 1500°C to make clinker. Cement manufacturers will finally grind the clinker and mix it with materials such as silica sand, hearth stone and water to make the common Portland cement.
The newspaper further pointed out that currently 90% of the carbon dioxide produced by the cement industry is released during the clinker burning stage, of which about 2/3 is released by heating limestone, and the remaining 1/3 is produced by coal combustion.
Considering the significant carbon dioxide emissions from the cement production process, some in the cement and building materials industries are currently exploring new approaches. The Wall Street Journal and other foreign media outlets have highlighted four approaches being explored in cement production: improving energy efficiency, using clean energy, using alternative raw materials, and using carbon capture technology. These approaches aim to effectively reduce carbon emissions and achieve the 2050 net-zero emissions target.
Improving Efficiency: Using Artificial Intelligence to Reduce Cement Carbon Emissions
Carbon Re, a British artificial intelligence (AI) materials science startup, uses AI and machine learning (ML) algorithm analysis to accelerate the decarbonization of building materials such as cement, thereby optimizing cement industry processes and fuel use.
Adian O’Sullivan, co-founder of Carbon Re, said that the main problem facing the cement industry is fuel waste. In particular, most cement production plants use excessive or poor-quality coal to produce clinker, which leads to large amounts of carbon dioxide emissions in the process.
According to Carbon Re's official website, the startup primarily uses AI digital twin analysis to analyze the control systems of cement kilns and related equipment. This digital analogy process determines the optimal parameters for the cement production system to achieve "minimum fuel consumption and maximum output."
"The application of AI in the cement industry has been relatively slow, but the AI machine deep learning (DL) used by Carbon Re can effectively improve the operating efficiency of cement plants and provide plant operators with more clear process operation suggestions. Most importantly, energy consumption and carbon dioxide emissions will be significantly reduced throughout the production process." O'Sullivan wrote on the company's website.
O'Sullivan gave another example, saying that if every cement plant could reduce fuel consumption by 2%, the world would have the opportunity to reduce carbon emissions by millions of tons. If this AI model can be further applied to heavy industry, which accounts for about 20% of total carbon emissions, it will be a great benefit to reducing global energy consumption and carbon emissions.
New fuel: Solar energy can also produce cement clinker
Germany's PV Magazine noted that Swiss-based solar startup Synhelion has partnered with Mexican building materials supplier Cemex to build highly concentrated solar receivers near Madrid, Spain, starting in 2022. The goal is to use these receivers to produce cement clinker that does not use fossil fuels.
Synhelion CEO Gianluca Ambrosetti explained that solar receivers can provide enough heat to produce concrete clinker. They work by installing mirrors on the equipment to reflect sunlight. When the light is concentrated on the top of Synhelion's solar receiver, it can heat the cement kiln to approximately 1482°C, thus producing clinker without using fossil fuels.
The company further explained, "Conventional clinker production is typically performed in rotary cement kilns at 1500°C, a process that is both extremely energy-intensive and emits significant amounts of CO2. However, the technology jointly developed by Synhelion and Cemex effectively separates and captures residual CO2 during the high-temperature clinker calcination process, eliminating the need for additional steps to address carbon emissions."
Solar Energy Magazine revealed that Synhelion and Cemex recently received US$3.2 million (approximately NT$100.2 million) in funding from the U.S. Department of Energy (DOE) to develop more efficient thermal energy storage systems and accelerate their mass production. The two companies aim to achieve commercial production of solar-powered cement clinker by 2030.
New Materials: Developing the World's First Negative Carbon Emission Technology Using "Natural Substances"
According to the American news website Quartz, Bahamian startup Partanna has broken away from the traditional building material model of using Portland cement as a binder and instead developed a carbon negative building material. This binder can enable buildings to continuously absorb carbon throughout their entire life cycle, similar to the carbon sequestration ability of forests.
Quartz Financial Network stated that the technology developed by Partanna is a world first. The adhesive is a new type of cement made from brine produced by desalination plants and slag produced during the steelmaking process.
Rick Fox, co-founder and CEO of Partanna, said that when carbon dioxide comes into contact with a natural mixture made of brine and slag, it can be processed to form a binder that is equally useful as traditional cement. "We cure this mixture at normal room temperature, so there is no excess heat generated in the cement production process," Fox said.
In addition, the adhesive strength of traditional concrete will gradually weaken after long-term contact with seawater. However, because Partanna adhesive is made from brine, the adhesive strength of this material after being affected by seawater is 25% higher than that of traditional cement. It is expected that this building material will help low-lying coastal areas resist the impact of climate change.
"Hurricane Dorian in 2019 wreaked havoc on my home island of the Bahamas, and I believe this sturdy building material is even more crucial to keep Bahamians safe in areas most vulnerable to climate change," said Fox, who was born in the Bahamas.
Partanna's official website also emphasizes that a 1,250-square-foot (116.13-square-meter) house built with brine cement is estimated to remove 182.6 tons of carbon dioxide from the atmosphere, equivalent to the annual carbon sequestration of 5,200 mature trees. Partanna is also collaborating with the Bahamian government, where approximately 1,000 houses are currently being built using this brine cement. Partanna is also in discussions with hoteliers in Las Vegas about using this new cement in future projects.
Carbon capture and storage: 400,000 tons of cement carbon emissions transported to the seabed for storage
The International Energy Agency (IEA) points out that carbon capture, utilization, and storage technology (CCUS) is a key means of reducing carbon emissions in the cement industry. It is estimated that by the end of 2030, 8% of the carbon dioxide produced by the global cement industry will need to be effectively stored. However, the cement industry's current investment in CCUS is still insufficient, and the research and development of related technologies is also progressing slowly.
Faced with this urgency, Heidelberg Materials, a listed German building materials company, announced that it has begun constructing a submarine CCUS facility and will use amine absorption to capture the carbon dioxide produced during the cement production process. The captured carbon dioxide will then be compressed into a liquid and sent into submarine pipelines owned by its partners, the Norwegian oil companies Equinor, Shell, and TotalEnergies, before being transported to the seabed near Bergen, Norway, for permanent storage.
The Wall Street Journal stated that Heidelberg Materials, the world's largest cement producer, expects to have the opportunity to officially put CCUS into cement production by the end of 2024. Once fully operational, it is estimated that it will be able to absorb approximately 400,000 tons of carbon dioxide annually. This capture and storage capacity will make the seabed storing carbon dioxide around Bergen, Norway the world's first large-scale CCUS site operated by the cement industry.
Christoph Beumelburg, Heidelberg Materials Communications Director, said: "The cement industry currently has considerable decarbonisation potential, and if the industry wants to effectively address its excess CO2 emissions, CCUS is definitely a technology we need to consider."
This article is reprinted with permission from Critical Commentary. The original title is "European and American startups create 'zero-carbon cement': using AI to accelerate decarbonization, solar-powered cement clinker production, and developing carbon-negative building materials." It is not subject to the terms of the CC license.
References:
1. The Wall Street Journal (August 24, 2023), Building Green: New Technologies to Create Less Polluting Cement
2. PV Magazine (August 7, 2023), Synhelion starts building solar tower for cement production
3. Quartz (October 20, 2023), The Bahamas is introducing the world’s first carbon-negative construction tech
4. Carbon Re (April 7, 2022), How AI is helping cement plant operators reduce energy consumption and carbon emissions
Source: Environmental Information Centre
