Green Cement  

The ABC's Catalyst show this week had a segment on green cement from a company called Zoobond - trying to reduce the huge carbon emissions that cement making currently entails.

An Australian company has started to make concrete which promises to dramatically cut the carbon dioxide ordinarily emitted during production. Concrete is the second most widely used material on earth, after water. Figures vary, but it’s estimated that the manufacture of cement, the reactive ingredient in concrete, is responsible for over 5% of the world’s CO2 emissions.

Using a technique to make geo-polymers similar to those found in some natural volcanic rocks, a concrete alternative called E-Crete is now being manufactured in Melbourne, which claims to have reduced the amount of CO2 ordinarily emitted in the manufacture process by an estimated 80-90%.

Narration: What’s the fast growing source of greenhouse gas?

You might be surprised but it’s cement. Cement’s already the 3rd largest man-made source of carbon dioxide - more than two billion tonnes of it a year. That’s after fossil fuels and defrorestation. And because of all the construction going on around the world, cement’s carbon footprint is growing rapidly.

In May 2007, the Mayor of London laid down a gauntlet: 60% cuts in carbon emissions by 2025 – that’s 25 years ahead of the UK’s national target – 25 years ahead of anywhere else in the world. So can a city do what a nation can’t?

London has faced many challenges in its long and colourful history, but this could be its biggest. Like all great cities, it has an insatiable hunger for power. 75% of the worlds’ carbon emissions come from cities. And yet cities are some of the places most at risk from climate change.

Stopping the City drowning is an unenviable responsibility, but it has fallen on the shoulders of Allan Jones MBE because of the extraordinary thing he did in the English town of Woking. Once there, he set the town on the path to independence of the national electricity grid, by generating all its own power.

Now, Allan has been asked to repeat what he did for Woking in Greater London - a city 75 times the size. London has a proud history of transformation under duress, but like the barriers on the Thames itself, the barriers that Allan and his compatriots face are immense. ...

Combined heat and power is not new – Manhattan was set up with it in the 1880’s. But when modern, centralised power stations were invented, CHP was quietly abandoned – Manhattan’s surrounds are on the grid.

In energy terms, though, centralised power stations are far less efficient. 2/3 of the energy produced is thrown away into the atmosphere as heat – with further losses over the grid.