No wonder the United Nations is worried. Making one ton of cement emits nearly one ton of carbon dioxide. With an area the size of Paris being built on every week globally, construction contributes heavily to climate change. In Australia, CO2 from building is tipped to double by 2050.
In Southeast Asia, climate change spells danger to government aspirations and peoples’ lives. United Nations maps show the very large areas of heavily populated coastal lowlands from China to the Indonesian archipelago exposed to drought, typhoons, floods and sea level rise.
The Thai and Indonesian capitals Bangkok and Jakarta expect to be increasingly flooded, and both governments have grand plans to protect the cities. Bangkok’s concept is to build a 100 km sea wall linking a string of artificial off-shore islands.
Jakarta is sinking by 25 cms per year into heavily saturated soil, worsened by communities having to draw water from wells because their numerous rivers are contaminated. Some of Jakarta’s 11 million people already live on land below sea level. There are two sea wall plans – one of 100 kms, the other 650 kms.
The proposed huge concrete sea walls indicate a far greater threat. South and Southeast Asian populations face the greatest danger world-wide from sea level rise.
Australia shares these problems. Our “typhoons” and Atmospheric Rivers from the same warm seas are also intensifying.
If this is all too much to contemplate, let’s just look at Australia’s urban growth and what we can do about cement and concrete. A good place to start is Ancient Rome.
The Romans learned about cement from the Greeks. Even before that a form of concrete was used in what is now Syria more than six thousand years ago. But it was the Romans who made a science of it over centuries. Their most highly developed cement was a mix of lime from limestone and volcanic ash from Mount Vesuvius and the volcanic arc surrounding the Bay of Naples. The bay was a Roman naval station from which the volcanic ash was shipped around their Empire, administered by the Roman legions.
Roman cement ingredients are highly reactive, binding together chemically when water is added. Mixed with stone aggregate, the Romans had an almost indestructible concrete so durable that the structures built with it still stand today. It could set under water so was used for ports and sea walls, bridges, sewers and aqueducts.
Roman cement inspired a flowering of Roman architecture, creating a ‘Concrete Revolution’. New buildings with curved shapes, complex arches, vaults and domes were commissioned by Roman emperors seeking fame and their place in history.
The Colosseum is built of stone and cement, erected on massive concrete foundations. It has 80 entrances leading to barrel-vault arcades and what were once marble seats for 50,000 spectators. For the opening ceremony the arena was flooded for a mock naval battle between rival “armies” manning flat-bottomed galleys. Overhead a huge retractable awning operated by hundreds of sailors could protect people from the sun.
With the fall of the Roman Empire, the technical knowledge of the Concrete Revolution was lost, though great Roman buildings like the Pantheon remained to inspire Medieval architecture. It was not till the early nineteenth century that an effective concrete was reinvented in England, the Portland cement we use today. Limestone is heated in ovens to a very high temperature, usually powered by burning coal, with CO2 emitted by both processes. It’s a climate change problem magnified by the enormous scale of demand for cement and concrete around the world.
As one of the very rich countries, Australia has a per capita CO2 emissions rate four times the world average. The population, its housing and consumption, is projected to continue to grow beyond 2050, the date we are committed to reach net zero emissions.
The Australian think tank Climate works Centre describes the scale of build: “New construction adds up fast – 51% of the buildings expected to be standing in 2050 will have been built after 2019.”
How can we justify those emissions multiplied by our high population growth rate? Only by an all-out clean technology effort.
Today’s conventional concrete can crumble after fifty years or less, bearing no comparison with two-millennium old Roman cement. The hope is for a stronger and more durable concrete which will allow engineers to design structures using less concrete while reducing greenhouse gas.
Scientists around the world are searching for a green cement – a Second Concrete Revolution in the making.
A radical green cement initiative is to make cement with CO2 factory waste. It’s happening in Newcastle, Australia. Cleantech entrepreneur Marcus Dawe asked “What can we do with CO2?” His answer: mineral carbonation.
“In nature, the CO2 in the air dissolves in rainwater. Over the ages this weathers rock, then deposits it as new carbonated minerals,” says Dawe. “We have found a way of industrially speeding this up, locking the CO2 away permanently in mineral feedstocks, and making useful products.”
After years of university research in Canberra and Newcastle’s Institute of Energy and Resources, MCi Carbon (Mineral Carbonation International) has teamed up with Orica’s fertiliser operation to open an industrial-scale demonstration plant on Kooragang Island, Newcastle. The plant funnels Orica’s waste carbon dioxide emissions into MCi’s carbonation reactors. The carbon from the CO2 binds chemically with pulverised rock or waste such as steel slag to produce as variety of carbonates. Magnesium carbonate makes a cement with a particularly low carbon footprint. The same technology can also decarbonise plasterboard production, cement blocks, steel, chemicals, glass, and potentially entire supply chains.
Overseas companies and banks have signed up. In Austria, RHI Magnesita will use the technology, transforming approximately 50,000 tons of captured CO2 per year to make fire bricks. MCi with Japanese international trader ITOCHU and construction giant Taisei will accelerate Japan’s transition to Net Zero. And Sumitomo Mitsui Trust Bank and Mizuho Bank have added to Japan’s investment in MCi.
This is exactly the sort of international cooperation which is essential in our deadly battle against climate change.
Oliver Howes was a writer-director at Film Australia and an independent producer, making documentaries and feature films. He has worked for the PNG government, in Japan and in Pacific states
Contributions to Pearls and Irritations
Your contribution will fund quality independent comment and analysis in Pearls and Irritations
Contribute
