Technology Roadmap Low-Carbon Transition in the Cement Industry

4. Carbon emissions reduction levers

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Technology Roadmap
Low-Carbon Transition in the Cement Industry
A theoretical minimum energy requirement of 
1.85-2.80 GJ/t clinker is defined by chemical and 
mineralogical reactions and drying needs, which 
vary depending on the moisture content of the raw 
materials (ECRA and CSI, 2017).
Long-dry-process kilns can be retrofitted to 
incorporate a precalciner and multistage preheater
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to dry and precalcine raw materials with recovered 
process excess heat before they enter the kiln. 
Different strategies can be implemented to improve 
the thermal energy intensity of clinker, beyond 
operating state-of-the-art kiln technology. These 
include increasing the burnability of raw materials 
by adding substances called mineralisers, which 
lower the viscosity and the temperature at which 
clinker melt begins to form. Operating the kiln 
with oxygen-enriched air can lead to up to 5% 
thermal energy savings (ECRA and CSI, 2017). In 
comparison with planetary and rotary coolers, grate 
clinker coolers enable greater EHR from hot clinker, 
which can be used for drying of raw materials 
when integrated with a precalciner (equivalent to 
0.1-0.3 GJ/t clinker energy savings) or for enabling 
electricity generation (ECRA and CSI, 2017). 
Some of these strategies have an impact on the 
electricity intensity of cement due to side effects. 
For instance, the addition of mineralisers may 
worsen the grindability of clinker. Other strategies, 
such as installing a precalciner, increasing the stages 
of the preheater or upgrading the clinker cooler, 
involve additional electricity needs to operate 
the new or upgraded equipment. These could be 
offset in specific terms, as many of these measures 
increase the clinker production capacity.
Electricity in cement production is used for cement 
grinding (31-44%), raw material grinding (26%), 
fuel grinding (3-7%) and clinker production 
(28-29%), with solid fuel grinding, cement loading 
and packaging accounting for the remainder 
(ECRA and CSI, 2017; Madlool et al., 2011). The 
use of efficient grinding and milling technologies 
decreases the global electricity intensity of cement 
by 14% by 2050 compared to 2014 in the 2DS.
The state-of-the-art grinding technologies 
considered in the analysis are high-pressure grinding 
rolls and vertical roller mills. These can theoretically 
19. An additional cyclone stage in a multistage preheater can result 
in a thermal energy intensity reduction of 0.08-0.10 GJ/t clinker. 
However, this is only possible if the raw material moisture 
content is below that which the preheater design considered, 
and if there are no dimensional constraints on the site (ECRA 
and CSI, 2017).
provide up to 50% (high-pressure grinding rolls) 
and 70% (vertical roller mills) electricity savings 
compared to the current widely used ball mills 
(ECRA and CSI, 2017). Electricity demand for cement 
grinding is highly dependent on product quality 
requirements. The higher the strength class needed, 
the finer the cement needs to be ground. Therefore, 
in-field achievable electricity savings from installing 
an efficient grinding technology rely on product 
fineness requirements. Other electricity saving 
strategies include cross-cutting measures such as 
upgraded cement process controls and the use of 
variable speed drives to run mechanical equipment 
across the site (e.g. grinding machines, fans, solid 
matter transport or kiln rotation).
Energy efficiency improvements are offset by 
additional energy requirements related to the use 
of other carbon mitigation levers. For instance, a 
greater use of alternative fuels (from 6% to 30% 
globally by 2050 in the 2DS), typically with lower 
calorific content, results in an increased specific 
thermal energy demand of clinker (an additional 
0.11 GJ/t clinker globally by 2050 in the 2DS). 
The reduction of the clinker to cement ratio can 
also incur an additional energy demand, such 
as the need to calcine raw clays used as cement 
constituents. This is estimated to result in almost an 
additional 0.35 GJ/t clinker produced by 2050 in the 
2DS globally, or around 11% of the global average 
thermal energy intensity of clinker in that year 
(Figure 8). 
The integration of carbon capture
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equipment 
in cement plants
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in the 2DS similarly leads to 
additional electricity demand and thermal energy 
use, with thermal energy use being specific 
to post-combustion capture technologies to 
regenerate the saturated sorbent. For instance, 
capturing CO
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from cement plants in the 2DS 
globally results in an additional 15-19 kWh/t cement 
or 19-24% of the electricity intensity of cement 
production considering only efficiency gains by 
2050. Environmental regulations to lower dust and 
emissions of nitrogen oxides and sulphur dioxide also 
lead to higher cement-specific electricity demand 
levels, as additional electricity is required to operate 
emissions avoidance or abatement equipment.
20. See the section below discussing carbon capture technologies 
for details of the technologies.
21. The 2DS vision considers CO
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emissions capture starting 
commercial-scale deployment in 2030.

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4. Carbon emissions reduction levers