Page 42 - 2021 Sustainability Report

ENVIRONMENTAL STEWARDSHIP

1 Limestone and other raw
materials quarried

2 Raw materials are ground
and blended

3 Raw materials are heated
to 2,850° F in a kiln

4 Heat transforms the materials
into pellets of “clinker”

5 Clinker is ground with gypsum
1 5 6
cement

6 Cement is stored and shipped
via truck or rail

7 Primary end use consumption
is concrete

During the calcination process, limestone is heated in excess of 2,800 degrees Fahrenheit. This breaks down the molecular
structure of the stone into clinker (mainly comprised of calcium oxide (CaO) compounds) and CO gas. While the solid
2
is emitted from the plant. In a modern kiln, more
clinker is subsequently ground and incorporated into cement, the CO 2
than 50 percent of the Scope 1 GHG emissions are a result of this calcination process, with the remaining emissions
coming from the combustion of fuels needed to heat the kiln and the on-site generation of electricity. 1

Cement producers have limited ability to abate or reduce process emissions resulting from calcination due to the
fundamental chemical composition of the limestone. While awaiting development of commercial-scale carbon capture
and storage technologies that may provide new, practical means of addressing the CO emitted from limestone, cement
2
producers must focus on opportunities to use lower-carbon fuel sources and improving energy efficiency in the
manufacturing process.

Carbon Capture and Sequestration

As recognized by a number of international organizations (including the International Energy Agency) as well as various
industry associations, the cement sector’s ability to contribute to limiting GHG levels in a manner consistent with the goals
of the Paris Agreement depends on successful future development and implementation of carbon capture and
sequestration (CCS) technologies on a commercial scale. In fact, the Science Based Targets Initiative (SBTi) at page 10 of
its draft Cement Science Based Target Setting Guidance published in March 2022 specifically acknowledged that “(i)n
addition to more traditional decarbonization levers already being implanted today, such as energy efficiency, fuel
switching, and clinker substitution, the IEA Net Zero report describes carbon capture and storage (CCS) as “central” to
mitigating process (geogenic) emissions in clinker production.” Similarly, further acceptance of even lower clinker content
cements by Departments of Transportation and ASTM in the United States will also be critical in allowing the cement
sector to achieve carbon neutrality across the value chain by 2050. We are monitoring these developments closely.

1 Testimony for the Congress of the United States House of Representatives Select Committee on the Climate Crisis hearing on “Solving the Climate
Crisis: Reducing Industrial Emissions Through U.S. Innovation”, September 26, 2019. Jeremy Gregory, PhD, MIT on behalf of the PCA.

40 2021 SUSTAINABILITY REPORT