Climate change is considered one of the most critical environmental concerns facing the world. It is caused by increased concentrations of greenhouse gases (GHGs) - mainly carbon dioxide (CO2) - in the atmosphere. These gases prevent reflected and radiated heat from the earth returning to space. The global cement industry significantly relies on energy to operate and produces about 5% of all man-made CO2 emissions. Depending on the process, making a metric ton of cement  typically produces more than 700  kilograms

of CO₂. About half comes from the chemical reactions in clinker production and 40% from burning fuel. The rest comes from electricity use and the transportation of raw materials and final products.

Monitoring is the first step to reduce emissions. We need accurate information on our emissions to develop effective strategies to curb them. All our cement plants are connected to an online reporting tool called the CO₂ Emissions Inventory Electronic Platform. This platform measures a range of indicators (e.g. volume of clinker, cement production, and fuel consumption) and then calculates CO₂ emissions based on the CSI protocol. The data help us to define actions to increase our efficiency, improving both our business and environmental performance.

Air emissions

Cement production releases different types of pollutants into the environment, mainly as airborne emissions. These emissions, primarily nitrogen oxides (NOx), sulfur compounds (SOx), and dust, are often controlled by national legislation and local regulation. We conform to the CSI reporting protocol on these emissions and approved a five-year capital expenditure of US$10 million, starting in 2007, to achieve our target of continuous monitoring of all of our kilns by 2015. We have invested in new equipment to reduce our air emissions at many of our sites. We believe that using residues from other industries as a fuel source helps to reduce our emissions, while safely disposing of society's wastes. Read some of our case studies on the use of alternative fuels and renewable energy >>

We have developed a CO2 strategy that takes into account all options to reduce emissions available to the cement industry. The following are the most important.

1. Use substitute materials that use less energy in their manufacture
   One of the most effective ways to reduce emissions is to replace clinker with less CO2 intensive materials. Substitute materials must have similar cementitious properties to clinker, maintaining the high quality of our cement. Suitable substitutes include blast-furnace slag from iron and steel making, and fly ash from coal-fired power stations. This method of substitution, known as co-processing, also provides a safe means of disposing of these industrial wastes.
   The clinker content of traditional Portland cement is around 95%. In Germany, we can produce high-quality cement with a clinker content of less than 35% using substitute materials. However, in many regions, reducing clinker content is often limited by the availability of suitable substitutes and government regulation.
2. Alternative fuels
   Cement kilns provide a valuable resource for burning society's wastes, such as biomass, household refuse, and used car tires. Such wastes provide substitutes for fossil fuels, reducing overall CO₂ emissions.
   Biomass such as wastes and by-products from forestry, agriculture, and food processing can be converted to alternative fuels. These are considered to have a neutral climate impact because biomass fixes carbon when it grows and releases it when burned as fuel, creating a neutral CO₂ cycle.
   We use advanced technologies to co-process alternative fuels in our plants. We have developed our own technologies for some waste streams like used tires, spent oils, and solvents.
   Alternative fuels provide a quarter of the total energy used in our European cement plants and a growing percentage of our fuel worldwide. Increasing the proportion of biomass fuels is an important part of our CO₂ strategy.
3. Energy efficiency
   We have reduced specific fuel consumption in some of our recently acquired European cement plants by sharing best practices from other sites.
   Co-processing also improves energy efficiency. For example, our Tamuin plant in Mexico adds ash from a nearby power station to its raw materials for cement making, reducing the temperature needed to form clinker. This technique has significantly reduced energy use.
4. Renewable energy
   Energy generated from renewable resources, such as wind, is carbon free. Our Mexican operations are participating in the development of a new wind farm in Oaxaca. The 250-Megawatt plant will be the largest in Mexico, supplying 25% of our annual electric energy needs in Mexico and reducing our CO2 emissions by 600,000 metric tons a year. The project has been registered as a Clean Development Mechanism (CDM) project under the United Nations Framework Convention on Climate Change.
   We continue to seek opportunities to generate and use renewable energy around the world.