The cement industry has largely escaped the attention of the world’s media and environmental campaigners despite contributing a higher percentage of global carbon emissions than the aviation industry. According to a report in the Guardian, cement plants across the world will annually release almost five billion tonnes of carbon dioxide by 2050.

The manufacture of cement is an energy-intensive process that involves the burning of vast amounts of fossil fuels to heat kilns to temperatures in excess of 1,500°C in order to burn limestone, the main ingredient of cement. Additionally, limestone experiences a fundamental change in its chemical structure at high temperatures, causing CO2 and other gases locked inside the rock to be released. Collectively, the industry produces five per cent of global anthropogenic CO2 emissions, of which half derive from the chemical process, and 40 per cent from burning fuel. By comparison, air traffic contributed two per cent of global carbon emissions in 2000, according to new research carried out at Manchester Metropolitan University.

Demand for cement, the key ingredient in concrete and mortar, is steadily increasing in line with the industrialisation of countries such as China, where half the world’s cement is produced. And it seems unlikely that the industry can reduce its environmental impact, because any potential emissions savings will quickly be swamped by the anticipated increase in global production.

December 2007