Reported emissions from the minerals sector increased from 103.2 million metric tons (MMT) CO₂e in 2011 to 116.4 MMT CO₂e in 2018, an increase of 12.8 percent. Reported emissions reached a maximum of 117.0 MMT CO₂e in 2014 before decreasing slightly in 2015 and 2016 and increasing slightly in 2017 and 2018. The cement production subsector is responsible for the majority of the emissions from this sector (nearly 60 percent). Gradual emission increases in the cement subsector were the most important driver of the overall increase emissions in the minerals sector, balanced somewhat by emission decreases in the lower-emitting glass and lime subsectors.

Cement Production. The emissions for cement production include both the process emissions and the combustion emissions from the burning of fossil fuels. Reported emissions from the cement production subsector have increased by 21.2 percent, from 56 MMT CO₂e in 2011 to 67 MMT CO₂e in 2018. Emissions increased by 2 percent to 7 percent each year until reaching peak emissions of 68 MMT CO₂e in 2015, dropping slightly in 2015 and 2016, and then increasing by about 1 percent per year in 2017 and 2018. Clinker is the component of cement that is responsible for most of the GHG emissions. The increase in clinker production can be attributed to an increased demand for cement in new residential and non-residential construction. As shown in the table below, there is a high correlation between clinker production and emissions.[1]

*Values for 2018 are preliminary figures.

Lime Manufacturing. The emissions for lime manufacturing include both the process emissions and the combustion emissions from the burning of fossil fuels. The process emissions consist of CO₂ generated during the calcination of limestone. Major uses of lime include industrial, chemical, and environmental applications. Reported emissions from the lime production subsector have remained relatively steady as demand for lime remained fairly stable. The emissions have varied from a low of 27.6 MMT CO₂e reported in 2016 to a high of 31.6 MMT CO₂e in 2014. Emissions for this sector increased between 2016 and 2018 due to increased lime production.[2] 

Glass Production. Glass production is an energy and raw-material intensive process that results in the generation of CO₂ from both the energy consumed in making glass and the glass process itself. The U.S. glass industry can be divided into four main categories: containers, flat (window) glass, fiber glass, and specialty glass. The majority of commercial glass produced is container and flat glass.[3] From 2011 to 2018, reported annual emissions from the glass production subsector has decreased from 8.4 MMT to 7.8 MMT CO₂e per year. However, there were 8 fewer glass production facilities reporting in 2018 than in 2011. In general, these fluctuations were related to the behavior of the export market and the U.S. economy. However, some commercial food and beverage package manufacturers are reportedly shifting from glass containers towards lighter and more cost-effective polyethylene terephthalate (PET) based containers, putting downward pressure on demand for glass.[3] 

Soda Ash Manufacturing. CO₂ is generated as a byproduct of calcining trona ore to produce soda ash. Commercial soda ash is used as a raw material in a variety of industrial processes and in many familiar consumer products such as glass, soap and detergents, paper, textiles, and food.[3] Approximately 50 percent of soda ash is used for glass production. Soda ash production has remained relatively steady over the last few years, which has resulted in little variation in the annual emissions from this subsector.[4] The annual emissions reported include both the process emissions and the emissions from burning of fossil fuels. The reported emissions have varied from a low of 3.8 MMT CO₂e in 2016 to a high of 5.4 MMT CO₂e in 2014.

Other Mineral Production. The other mineral production facilities are those operating under NAICS codes beginning with 327 (non-metallic mineral product manufacturing). Unlike the other subsectors, these facilities report only GHG emissions from stationary fuel combustion sources. Between 2011 and 2018, the emissions reported for the other minerals production subsector increased by 74.2 percent (2.6 MMT CO₂e), which was due to both an increase in the number of facilities reporting (30 more facilities reported in 2018 than in 2011) and an increase in the average annual emissions per facility (up from about 45,000 MT per facility in 2011 to 57,000 MT per facility in 2018).

References

[1]    U.S. Geological Survey (USGS), Cement. Mineral Commodity Summaries, February 2019.

[2]    USGS, Lime, Mineral Commodity Summaries, February 2019.

[3]    U.S. Environmental Protection Agency (USEPA), Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990-2017, 2019.

[4]    U.S. Geological Survey (USGS), Soda Ash. Mineral Commodity Summaries, February 2019.