New U.S. Energy Information Administration (EIA) figures reinforce a well-worn statistic in the climate change discussion: portland cement production accounts for about 5 percent of global carbon dioxide emissions. The carbon load reflects high temperature raw feed preheating and kiln phases, plus power-hungry clinker grinding.
Drawing data from its just-released 2013 Annual Energy Outlook, EIA cites stark figures cement customers and producers might encounter in a construction market influenced by green building rating systems and carbon-tracking government agencies. Cement is the most energy-intensive of all manufacturing industries; its share of national energy use is roughly 10 times its contribution to gross output of goods and services. In raw numbers for a 2010 baseline, EIA contends, cement production represented a) 0.25 percent of U.S. energy consumption, 97.7 quadrillion Btu; and, b) 0.02 percent of gross national output, $24.6 trillion.
Anticipating a new era of environmental scrutiny for concrete and cement—driven partly by the 5 percent global CO2 emissions factor and consumption benchmarks like those derived from the EIA Annual Energy Outlook—the RMC Research and Education Foundation and Portland Cement Association launched the Massachusetts Institute of Technology-hosted Concrete Sustainability Hub (CSHub) in 2009. Foundation and PCA representatives have steered research to address challenges of a business or product synonymous with CO2 emissions or high-carbon key ingredient.
In life-cycle cost or assessment projects, CSHub researchers have consistently proved the value and long-term performance of concrete in two high volume applications, pavements and buildings. They have applied complex math to demonstrate the prospects for reduced fuel consumption of vehicles traveling on concrete versus asphalt roads, and lower heating and cooling costs—and hence energy consumption—in concrete versus steel buildings or wood frame homes.
In cement projects, CSHub staff have studied a) ways of optimizing clinker phase energy by limiting kiln time and lowering process temperatures; b) clinker grinding mechanics to reduce the electricity required for finishing ASTM C150 product; and, c) the chemistry of dry and hydrated powder with an eye to improved concrete durability.
Additional CSHub research will further arm Foundation patrons and PCA members responding to public and private construction interests' calls for improved EIA stats and lower global CO2 emissions.