While a Wyoming coal plant and one Chevron refinery are the largest pollution sources for California, the three industries that together account for 40% of California’s GHG emissions include electric utilities, oil refineries and cement manufacturers – so these are the three industries most impacted by California’s climate legislation, AB32, which will begin next year.
California is the largest cement-producing state in the U.S., accounting for between 10% and 15% of U.S. cement production and cement industry employment with about 2,000 workers between 31 cement facilities.
The fossil energy that it takes to heat the cement mix up to 2,642 degrees Fahrenheit is why cement production has such high carbon dioxide emissions.
Currently cement producers in the state use 1,600 GWh of electricity, 22 million therms of natural gas, 2.3 million tons of coal, 0.25 tons of coke, and smaller amounts of waste materials, including tires.
By requiring that they use cleaner fuels; AB32 will reduce in-state carbon emissions while preventing “carbon leakage” from competing cement companies across our border by requiring the same standards for cement imports from other states.
Other air toxic emissions such as mercury and other criteria pollutants will also be reduced. California cement production accounts for almost 90% of statewide mercury pollution.
Replacing coal or petroleum coke with more natural gas will cut in half the greenhouse gas emissions from the heating process. Other options include using biomass solids and waste-derived fuels or co-firing fuels. Adding in efficiency technology will further reduce that.
The second way to reduce CO2 emissions in cement production is to require that it blend materials such as limestone to replace some of the clinker in the production of Portland Cement. Currently most cement is mixed from powdered alumina, silica, lime, iron oxide, and magnesium oxide. Replacing more with limestone reduces the quantity of fuel combusted and the CO2 liberated through pyro-processing of limestone and meet performance and safety specifications.
While coal burned in furnaces contributes the most to cement production pollution, electricity itself also accounts for the next largest source of polluting energy in cement production, which provides an easy alternative. Simply switching to solar power would reduce their carbon emissions. Electricity is mostly used in machine drives, for grinding and crushing, and to transport materials around facilities. Only about 10% is currently used to create heat.
AB32 will put pressure on innovation which will drive new green jobs in the state. The low carbon cement developed by California companies like Calera, (now up to 125 employees), will generate international business opportunities for a new green cement industry.
It takes 3 to 5 gigajoules of energy to make every ton of cement. Worldwide the industry uses at least 8 billion gigajoules of energy a year, producing 6% of global carbon dioxide emissions.
Concrete production has boomed in recent decades as developing countries add freeways and buildings, growing from 594 million tons in 1970 to 2.3 billion tons in 2005. As the growth of leading producers like China and India continues – global cement production could reach 5 billion tons by 2030, which will drive innovation into greening cement production, whether that’s here in California, or abroad in China.
Source: Lawrence Berkeley National Lab
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