Cement is an essential component for our economic and social development as it is a vital component of concrete, water will be the second ingredient used commonly. Nowadays, cement is used for the construction of homes, hospitals, schools, roads, dams, bridges, and tunnels. It is an essential part of virtually all types of construction projects. The annual global production of cement is around 3.5 billion tons of ordinary Portland cement, which contributes approximately 7-8% of global anthropogenic CO2 emissions and equates to about 622 kg of CO2 per ton of cement produced, significantly impacting the environment.
Cement acts as a binder in concrete, holding fine and coarse materials together and although it only accounts for approximately 12% of its volume, it is responsible for almost all of the CO2 emissions associated with its production. The process begins with raw materials such as limestone (CaCO3) and clay, which are grounded into a fine powder and then heated to high temperatures (around 1450°C) in a cement kiln to form clinker (rounded lumps of 1 to 25 mm). The clinker is then grounded into a fine powder and gypsum is added to produce cement.
Reducing CO2 emissions in the production of this material while meeting the expectations of its growing demand is a major challenge. As part of this challenge, improving energy efficiency can significantly reduce emissions. This may involve upgrading equipment such as kiln inlet and outlet seals, among others; optimizing processes that directly impact production; and employing advanced technologies available on the market.
Other strategies involve the use of alternative fuels, better design and construction practices, and increased use of building information modeling (BIM) and modular construction.
With the same goal, the implementation of carbon capture, use and storage (CCUS) is a fundamental technology to decarbonize cement manufacturing. CO2 emissions in cement production arise from both the production process and the combustion of fuel. This method involves a set of technological processes with the purpose of reducing carbon emissions in the atmosphere, capturing the CO2 generated on a large scale in fixed sources to store it underground safely and permanently.
Today, although the commercial deployment of CCUS in the cement industry is limited, there are several notable examples as the following:
• Texas, USA: One site has been in operation since 2014, capturing 15% of CO2 emissions through post-combustion capture with solvent absorption.
• Anhui Conch, China: Operational since 2018, this plant captures 50,000 tons of CO2 per year.
• Norcem, Norway: A large-scale plant is scheduled to be operational by 2024, with a target of a high CO2 capture rate.
• Lehigh Cement, Canada: Feasibility studies are underway for a large-scale CCUS implementation.
• Dalmia Cement (Bharat) Limited, India: This company is working with a CCUS technology provider to build a plant capable of capturing 500,000 tons of CO2 per year in Tamil Nadu, India.
Carbon capture, use and storage has a lot of potential, as do other available technologies, however, several challenges remain. The processes are usually energy-intensive, expensive, and the investments are high as well if they are to be economically viable. In addition, the infrastructure to capture, transport and store CO2 needs to be developed and expanded.
Implementation of these technologies, along with other emissions reduction strategies, such as reducing false air in the process, which contributes to reduced fuel consumption and can be achieved mainly with an efficient kiln seal. All of this can help the cement industry move towards net-zero emissions. Continued innovation, supportive policies, and investments in research and infrastructure will be crucial to harnessing the full potential of these technologies and achieving a sustainable future.
Source: https://energycentral.com/