Annual production worldwide is almost two billion tonnes.

What is not commonly known is that cement manufacture (one of the constituent raw materials) is one of the most damaging industrial processes around, contributing approximately five per cent of greenhouse gas emissions worldwide, far more than the airline industry that receives a far worse press.

What is it about cement-making that is so damaging and are there any technologies available to mitigate these problems?

The basic process is to crush limestone and blend with other materials that contain the right proportions of calcium, silicon, aluminium and iron oxides.

The crushed material is then heated to approximately 1,500C, making the components react and fuse together.

The finished product is then mixed with gypsum and other materials to make cement.

Cement is mixed with sand, gravel and water to then make concrete.

Most of the greenhouse gases are produced during the manufacture process, which is very fuel intensive.

For every tonne of cement manufactured, 900 kg of carbon dioxide is produced.

The only realistic ways of reducing the global warming potential of manufacturing cement is to use renewable fuels or to decrease demand for cement.

There appears to be very little alternative to using concrete for construction, which leaves only the renewable fuel option.

There are very few fuels available that have enough calorific value to produce the amount of heat required.

Apart from conventional fuels such as gas, many cement kilns use fuel that is made from waste materials such as solvents, glues and other residual material from other manufacturing processes.

This type of fuel can have lower carbon dioxide emissions, but is associated with other air pollution problems.

Some research and development work has also been undertaken on changing the minerals needed for a cement mix to try to reduce the amount of heat required for the fusion reactions to take place.

Greenhouse gas emissions from manufacture are not the only source of air pollution from the cement industry.

Transport, dust, quarrying and chemical pollutants are all environmental impacts that cannot be ignored, either.

It seems that the cement-making industry is alive to the issue of global warming and its environmental footprint.

The Cement Sustainability Institute has been set up to represent the largest manufacturers (about half the industry) to try to deal with these issues before attention is focused away from the airline industry and on to their activities.

By tackling many of the issues themselves the industry hopes to avoid heavy government regulation.

With demand for cement likely to increase substantially in years to come, especially with the development of China, it is easy to see why the cement industry is eager to try to clean up its image.