The CO2 emission reduction levers

Savings in Clinker Production

This includes CO2 reductions through use of decarbonated raw materials, energy efficiency measures, use of sustainable waste materials (“alternative fuels”) to replace fossil fuels and innovations such as use of hydrogen and kiln electrification.

Use of decarbonated raw materials to replace some of the limestone in the kiln reduces the total emissions from decarbonation of the limestone. By definition the decarbonated materials, such as the fine material from recycled concrete, do not emit CO2 when heated because they have already had the CO2 removed (de-Carbon-ated). Globally this is forecast to provide a 2% reduction in total emissions from the sector.
Thermal energy efficiency measures are already widely implemented across the globe through deployment of existing state-of-the-art technologies in new cement plants and retrofitting existing facilities. Further improvements will be made. with many newer energy efficient cement plants in emerging economies, this is an area where these regions have already made good progress.

It is to be noted that with an increase in use of alternative fuels, there can be a slight decrease in the thermal energy efficiency. Higher substitution rates of alternative fuels in combination with different parameters, for example burnability, higher moisture content, design and size of the plant, can typically result in a slight increase in thermal energy demand. This effect was taken into account in the forecasting.

Alternative fuels are derived from non-primary materials i.e. waste or by products and can be biomass, fossil or mixed (fossil and biomass) alternative fuels. There are current examples of cement kilns operating with greater than 100% alternative fuels which demonstrates the technical and environmental potential of this lever.

The industry is a well-established consumer of non-recyclable waste-derived alternative fuels from a range of sources, for example, municipal, agricultural, chemical and food production. The extremely high temperatures and residence times reached in cement kilns ensure these are managed in a safe and environmentally sound way. Supply chain logistics and infrastructure, permitting and waste policy to reduce/eliminate waste to land fill are required to support the industry in increasing their use of alternative fuels.

Use of Alternative fuels deliver CO2 savings

• Emissions from pure waste biomass and from the biogenic carbon content of mixed fuels is considered as climate neutral in accordance with the Greenhouse Gas Protocol. Therefore, with an increasing use of these there is a corresponding reduction in fuel CO2 emissions. These are reported in the roadmap as part of the “saving in clinker production”.

• Utilisation of fossil waste fuels in cement plants results – in accordance with the Greenhouse Gas Protocol – in CO2 and even GHG emission reductions at landfills and incineration plants. “Savings in fossil waste fuels” reflect the CO2 emission reductions achieved at waste disposal sites as a result of alternative fuels utilisation in cement plants.

On average globally, alternative fuel use is forecast to increase from the current 6% to 22% and 43% by 2030 and 2050 respectively. Higher percentages are forecast in North America and Europe. The biomass fraction of alternative fuels is forecast to remain at one third.

On average globally, fossil waste fuels use is forecast in line with alternative fuels to increase from the current 4% to 15% and 28% by 2030 and 2050 respectively. Innovations such as use of hydrogen and kiln electrification are forecast to play a small role from 2040.

Savings in cement and binders

At the cement plant or the concrete plant, fly ash, ggbs, ground limestone and other materials can be added to deliver concretes with reduced CO2 emissions but still the required performance. In some applications the concrete performance is enhanced. This lever is also referred to as clinker02 substitution. In this roadmap we use the term clinker binder ratio.
Availability of suitable materials around the world varies now, and will into the future, because for example fly ash comes from coal fired power stations and ggbs from the steel industry’s blast furnaces and these industries are also transitioning.
In coming decades there will be increased use of ground limestone and the introduction of calcined clays to both compensate for reduced supply of fly ash and ggbs, and further reduce the clinker binder ratio. Calcined clays rely on clay deposits that are geographically spread and sufficiently abundant to meet projected demand.
Whilst availability of materials can be a limitation on clinker binder ratio, client acceptance is a current barrier in fully exploiting this lever in some developed and emerging economies.

Efficiency in concrete production

In terms of concrete production, industrialisation is the key specific lever. Moving from small project site batching of concrete using bagged cement to industrialised processes offers significant CO2 emissions savings because of the adherence to mix specifications and quality control. In some emerging economies such as India, the vast majority of concrete production is currently on project sites. A transition to industrialised production has been seen in other countries.
More broadly utilisation of admixtures, improved processing of aggregates are good opportunities for CO2 emissions savings in concrete production. These savings have already been implemented by parts of the industry, but broader and deeper application will deliver further savings.
On average globally, optimisation of concrete production in terms of binder utilisation can lead to binder demand