Portland cement injects a large amount of the world's carbon dioxide into the atmosphereIs this sentence supposed to make sense?
No! Volcanos spew alot of CO2 into the atmosphere but no one in academe seems to care!
This looks like an answer in search of a question.
whats the agenda here? and why so long to figure out the difference between concrete and stone?
I wonder about that, too.
"Carbon dioxide emissions from a cement plant are divided into two source categories: combustion and calcination. Each accounts for about one-half the total CO2 emissions from a cement manufacturing facility. The combustion-generated CO2 emissions are related to fuel use. The calcination CO2 emissions are formed when the raw material is heated and CO2 is liberated from the limestone. Calcination is a necessary key to cement production. Therefore, the focus of reductions in CO2 emissions during cement manufacturing is on energy use, and since 1975, the cement industry has reduced GHG emissions from fuel use by 33 percent. Today, the cement industry accounts for less than 1.5 percent of U.S. CO2 emissions, well below other sources such as electric generation plants for heating and cooling (33 percent), transportation (27 percent), and industrial operations (19 percent)."
http://www.bipac.net/page.asp?g=PCA&content=issue_greenhouse&parent=PCA
Had to go look.
Cement manufacturing is the third largest cause of man-made carbon dioxide emissions. While fossil fuel combustion and deforestation each produce significantly more carbon dioxide (CO2), cement-making is responsible for approximately 2.5% of total worldwide emissions from industrial sources (energy plus manufacturing sectors).
Cement is a major industrial commodity. Manufactured commercially in at least 120 countries, it is mixed with sand and gravel to make concrete. Concrete is used in the construction of buildings, roads, and other structures, as well as in other products and applications. Its use as a residential building material is particularly important in countries where wood is not traditionally used for building or is in short supply. Annual CO2 emissions from cement production in nine major regions of the world are shown in Figure A below.
Large quantities of CO2 are emitted during the production of lime, the key ingredient in cement. Lime, or calcium oxide (CaO), is created by heating calcium carbonate (CaCO3) in large furnaces called kilns. Calcium carbonate is derived from limestone, chalk, and other calcium-rich materials. The process of heating calcium carbonate to yield lime is called calcination or calcining and is written chemically as:
CaCO3 + Heat -> CaO + CO2
http://www.cs.ntu.edu.au/homepages/jmitroy/sid101/uncc/fs030.html
Is this sentence supposed to make sense?
Isn't it obvious? Ancient Egyptians caused global warming!