Page 64 - Martin Marietta - 2024 Sustainability Report

ENVIRONMENTAL STEWARDSHIP

Understanding the Impact of Blending Alternate Fuel Use
and Fuel Choice
Similarly, not only is clinker substitution different around
While we are proud of these achievements — and, in fact, the world, but the reported numbers are being generated
as discussed below, we have committed to further reduce using different calculation methods. Our reported intensity
the carbon intensity of our cement and Magnesia is based upon the USEPA Clean Air Act Part 98 and the
Specialties businesses — we also believe it is important to data generated by our Continuous Emission Monitors
recognize both critical regulatory differences between the (CEMs) and reflects actual measured CO .
2
U.S. and the EU (and other international jurisdictions) and
In addition, alternative fuel use by the cement industry
differing calculation methodologies that result in
in the United States averages only 15 percent of the fuel mix,
meaningful differences in the makeup of corresponding
compared to 36 percent of the fuel mix used in the European
end-products and reported emissions metrics. Those
Union and as high as 60 percent in Germany. In large part,
differences, in turn, make like-for-like comparisons of the
this is because combustion of secondary alternate fuels is
emissions performance of such companies challenging.
incentivized in the European Union, whereas in the U.S.
environmental laws and USEPA regulations create hurdles to
Clinker Substitution and Blending
using these materials as fuel sources. Moreover, the
calculation of reportable CO emissions under international
2
For example, outside of the U.S., the allowable rate of
regulations differs materially from the calculation allowed
“clinker substitution” — the replacement of ground clinker
under USEPA regulation. The European Union Gross CO 2
in cement with alternate materials such as pozzolan, slag
Emission rates exclude CO emissions from biogenic fuels
2
and fly ash — is much higher than it is in the U.S. because
while the widely reported Net CO emission rates using the
2
of the limitations imposed by ASTM and Department of
GCCA method as noted above do not include the biogenic or
Transportation (DOT) standards for cement. While our
alternative fuel CO contributions. Again, if we used a
2
clinker substitution rate (like other U.S. producers)
hypothetical 75% clinker factor and calculated our
generally does not exceed 20 percent, the average clinker
emissions using the GCCA calculation method and our
substitution rate for international cement companies is in
current fuel mix, we estimate that our carbon intensity
the range of 28 percent to 50 percent, depending on the
would see a further reduction to approximately 0.489
type of cement. Accordingly, even where their clinker
1
net metric tonnes of CO /metric tonnes of cement
2
intensity (the amount of CO generated in producing a
2
equivalent basis.
tonne of clinker) is comparable to our 2024 rate of 0.685
gross metric tonnes of CO /metric tonnes of clinker (and in
2
many cases is actually higher), international cement
companies can reduce the carbon intensity they publicly
report by simply substituting higher percentages of non-
clinker products for clinker in their end product, rather
than actually reducing total emissions or improving
efficiencies in the manufacturing process.
In fact, if we used a hypothetical 75% clinker factor
for our cements, we estimate our carbon intensity
would be reduced from 0.550 to approximately 0.514
gross metric tonnes of CO /metric tonnes of cement
2
equivalent.

1 European cement standard EN 197-1 “Cement – Part 1: composition, specifications and conformity criteria for common cements”, as reported by CEMBUREAU.

62 2024 SUSTAINABILITY REPORT