Between four and six percent of the total worldwide carbon dioxide emissions related to human activity stem from the global cement industry. Minimising these emissions is one of the main sustainability challenges facing our industry.
Some 60 percent of carbon dioxide emissions from cement production come from the calcining process, when we produce the intermediate product clincer. The remaining 40 percent of emissions come from the combustion of fuels used to produce heat during the production process.
The carbon footprint from the production of both concrete and aggregates is relatively small compared to that for cement production and relates primarily to transportation and energy use during production.
Direct CO2 emissions = CO2 from fuels and raw material (Business Line Cement only)
Direct CO2 emissions; kg CO2 per ton cement
We have formulated a zero vision for CO2 emissions over the product’s life cycle. It requires actions in five areas:
- Energy efficiency
- Using biomass as energy
- New cement types
- Carbon capture and storage (CCS)
1. Energy efficiency
We are continuously improving our energy efficiency step by step by replacing old machines, improving processes and optimizing production.
2. Using biomass as energy
As part of our work to replace coal with alternative fuel sources, we strive to increase the amount of biomass in our fuel mix. In Northern Europe we have total of 19 % biomass in our fuel. Our best plans in Slite and Brevik has 23 % of biomass in its fuel mix. The main sources of biomass are woodchips, paper, textiles and animal meal.
3. New cement types
Clinker is an intermediate product in the cement production. The clinker is grinded to produce cement. By replacing parts of the clinker with other products, we lower the carbon footprint of the cement. The main replacement material is fly ash, which is a waste product of coal-fired power plants. Lime and slag which are both waste products from the iron industry, are also used to reduce the clinker content. Our cement has an average clinker content of 83 %.
4. Carbon capture and storage (CCS)
A world-first project for carbon capture within the cement industry has been underway at our plant in Brevik, since 2013. Four technologies have been tested with good results. A feasibility study with the aim of establishing a framework for a full-scale carbon capture facility will be run in 2016. The project and the study are government funded and are managed in cooperation with the European Cement Research Academy (ECRA).
Hardened concrete absorbs CO₂ through a slow process called carbonation. This process continues even after the concrete products many years of use. If used concrete is crushed down, the speed of the carbonation can be further increased. Calculations show that concrete constructions in Sweden and Norway absorb 500,000 tonnes of CO₂ per year.
We produce large volumes of products, and transporting these is a source of carbon emissions. We aim to use sea transport wherever possible especially for cement and aggregate deliveries. Ready-mixed concrete and concrete elements are mainly transported by road.
Development of new concrete mixes with a lower carbon footprint is based both on new cement types as well as optimizing the concrete mix. It is possible to produce carbon with as much as 50% reduction in CO₂ footprint compared to standard European concrete. In Norway, low-carbon concrete products have their own standardization.
Comment: KPIs regarding NOx and SOx emissions will be added in August 2016.