Civil Engineering Reference
In-Depth Information
including CO
2
during cement manufacturing. These efforts also reduce the nega-
tive environmental impact of the cement industry.
For example, due to improvements in fuel efficiency as well as in power util-
isation technology in Australian cement manufacturing industries, a reduction of
about 23 % in emission of CO
2
per tonne of cement production was observed in
2009, in comparison to that observed in 1990, which is depicted in Fig.
1.3
(Cement Concrete Aggregate Australia
2010
). However, the application of modern
technology to reduce CO
2
emissions and improving the fineness of cement clinker
for getting better technical properties can increase the thermal and electrical
energy consumptions. Research is going on to develop nano-catalyst to reduce the
clinkering temperature which will subsequently reduce the emission of CO
2
(Sobolev et al.
2006
).
One recent global effort is the ''The Cement Sustainability Initiative (CSI)''. A
total of 24 major cement producers, which account for about one-third of the
world's total cement production with operations in more than 100 countries, got
together to reach the goal of sustainability in cement industry. In this initiative,
four points were identified to control the emission of greenhouse gases: thermal
and electric energy efficiency, alternative fuels, clinker substitution, carbon cap-
ture and storage (CCS) (CSI Report
2009
). Except for the last point, which is still
at a demonstration stage, positive impacts of the other three points can already be
seen.
Carbon capture and storage (CCS) is not yet a fully developed technology and
additional research and demonstration are necessary to get benefits from this
technology. However, several feasibility studies were already conducted and gave
promising results. Post combustion capture techniques such as chemical absorp-
tion, membrane technology, oxy-fuel technology and carbonate-looping technol-
ogy are some promising technologies that can provide solutions to control CO
2
emission. Moreover, technological, societal and economical aspects of these
technologies must properly be addressed before their application.
In the next two sections, two common practices used to reduce global fuel
consumption and emissions of CO
2
into the atmosphere of the cement industry,
namely the use of alternative fuels and waste materials, will be briefly described.
1.5.2.1 Use of Waste Materials in Cement Kiln and Clinker Production
Several waste materials are nowadays used in cement kiln either as alternative fuel
or as raw materials. According to a GNR report in 2006 (CSI Report
2009
),
globally 7 % of total fuel energy consumption in manufacturing of cement came
from alternative fuels comprising biomass and energetic waste materials. Biomass
has a great potential to be used as alternative fuel in cement kiln. Pure biomass
such as animal meal, waste wood, saw dust and sewage sludge can be used to
replace large amounts of fossil fuels and has the potential to reduce the emitted
amounts of CO
2
. Cement kilns can burn some waste materials such as used motor
oil, spent solvents, printing inks, paint residue, cleaning fluids, waste textiles,
