Climate change is one of today’s most pressing issues. While cement offers numerous environmental benefits from a lifecycle perspective, production is energy-intensive, representing as much as 4-5 percent of global CO2 emissions. To meet this key challenge, we are increasing our use of alternative fuels and work to improve process efficiency.
CO2 emissions from cement production
Most of the cement industry’s CO2 emissions derive from the calcination process, when limestone is heated and split into calcium oxide and CO2. These emissions are an inevitable result of this key chemical reaction and account for 60-65 percent of total CO2 emissions from the cement production process.
The remaining CO2 emissions derive from the fuel used to generate the energy needed for the limestone to react and become the fine dust that is cement, the binding agent of concrete. Thanks to the CO2 uptake capabilities of concrete, the CO2 emissions from the cement production process are to some degree offset when the concrete is used and disposed of.
Our CO2 objectives and results HeidelbergCement Group has set a target of 15 percent reduction in specific net CO2 emissions by 2010 (CO2/ton cement), compared to levels in 1990. At HeidelbergCement Northern Europe we have already reached this target and are continuously working to do even better. In 2007 the plants emitted 783 kg CO2/ton cement, which is equivalent to a reduction of 17 percent since 1990.
The ambition is to reduce emissions even further at all the plants.
Increasing our use of alternative fuels Although fossil fuels are still our principal energy source, we want to increase the use of alternative fuels. By continuously replacing non-renewable fuels with alternative energy sources, we can preserve natural resources and decrease fossil CO2 emissions. By also increasing the use of biomass, which is neutral in the CO2 accounting, we can reduce the negative greenhouse gas impact from cement production by the same proportion. Significant sources of biomass include
forest products, agricultural crops, paper and textiles, sewage sludge and food production waste.
Turning waste into energy All communities produce waste and while much can be recycled, certain products, such as tyres, plastics and solvents, must be handled with care. The handling of such residual products poses a challenge to society, while, for us, it is an increasingly important source of energy. Since cement kilns require high temperatures, they
are ideal for the combustion of alternative fuels – especially residual products. By using waste, which would otherwise have been disposed of in landfill, we can replace fossil fuels and turn a problem into a resource creating a win-win situation for us and society.
Testing of waste derived fuel (RDF) and hazardous waste was fist started at the Brevik plant in 1987. Today, almost 50 percent of the energy needed in Brevik comes from alternative fuels and the goal is to increase the substitution level to 60 percent by 2010.
In Slite alternative fuels have been used since early 1990’s and today almost 30 percent of fossil fuels are replaced by alternative fuels in the form of car
tyres, pellets and animal meal.
The Kunda cement plant began using alternative fuels in 2000 and the, residual products used, such as waste oils, waste from the oil shale chemical industry and benzoic acid residue provide today about 10 percent of energy requirements at Kunda.
Excess heat from production Cement production involves extensive heating and cooling. Heat is needed to calcinate the limestone and cooling is needed to preserve the cement minerals created in the process. Outside air is used to cool the clinker – this warms the air,
which is then used to dry raw materials entering the process.
At the Slite plant, excess steam is used to generate electricity for reuse in the plants. Here the electricity from excess heat corresponds to 17 percent of the total electricity
consumed.
At the Skövde plant, excess heat from production is used to provide district heating, enhancing energy efficiency in the community.
Using more alternative raw materials We use alternative raw materials both to replace energy-intensive clinker, the main intermediate product in cement production, and as additives in the cement grinding process. Alternative raw materials used include blast furnace slag from steel production and fly ash, a by-product from coal-fired power plants. Combustion ash is also reused in production, replacing energy-intensive clinker and saving non-renewable natural resources such as limestone.