PROPERTY TRANSACTION GUIDE

Cement firms may soon lead carbon emissions, warns report

Guardian, Monday, 2nd Feb 2009

With cement manufacture already among the most energy-consuming and polluting industrial processes, WWF estimates that unless cement plants become more efficient or transition to renewable energy sources, the industry - now responsible for some six per cent of human-caused greenhouse gas emissions - is likely to become a larger contributor to climate change than the European Union by 2030

A NEW report released by the global group WWF has warned that unless cement industries cut their greenhouse gas emissions, it may become a larger contributor to climate change than the European Union by 2030.

The versatile construction ingredient has been commonplace since the Roman Empire, but production has boomed in recent decades, rising nearly 400 per cent since 1970. Global cement output may reach five billion metric tonnes by 2030, driven mainly by growth in the top two producing countries, China and India, according to a December WWF report.

But cement manufacture is among the most energy-consuming and polluting industrial processes. WWF estimates that unless cement plants become more efficient or transition to renewable energy sources, the industry - now responsible for some six per cent of human-caused greenhouse gas emissions - is likely to become a larger contributor to climate change than the European Union by 2030.

Alternatives have emerged this past year, however, that may redefine the future of cement. One company, California-based Calera Corp. claims to have found a way for cement production to absorb more carbon dioxide than it emits, acting as a vehicle for carbon capture and sequestration, or CCS.

Similar to how certain corals produce reefs by excreting dissolved calcium carbonate, or limestone, Calera sends carbon dioxide emissions through seawater to create a chalky carbonate byproduct. This cement substance is then mixed with aggregate and water to create concrete. Its production avoids the need to heat the cement materials in coal-fired kilns, while sequestering carbon throughout the process, the company says.

For every ton of cement produced, two-fifths of a tonne of carbon dioxide is stored, according to founder Brent Constantz.

Constantz opened his company's first demonstration site in August 2008. Located about 90 metres away from a natural gas-fired power plant, the Calera facility aims to filter more than 90 per cent of the plant's carbon dioxide emissions through seven 11-million liter seawater tanks that sit adjacent to the Pacific Ocean.

"Gas-powered plants are not our principal aim. Our principal aim is coal plants around the world. We're spending lots of time interviewing different coal plants in the U.S. and other parts of the world as well.... The challenge is to decide how many plants to develop in parallel," Constantz said.

Although the test facility so far produces at most five tons of cement per day, the technique is quickly gaining attention around the world. Aided by the connections of its main investor, venture capitalist Vinod Khosla, Calera is discussing projects in Australia, the Netherlands, Saudi Arabia, and the United Arab Emirates (UAE), which is considering using the material in its Masdar City project, Constantz said.

Calera is not alone, however. California-based Carbon Sciences plans to mix cement with power-plant emissions and waste material from coal and steel production. Carbon Sense Solutions in Nova Scotia, Canada, redirects emissions from pre-cast concrete plants into new cement. And London-based Novacem says its magnesium silicate cement will absorb enough emissions to make it carbon negative.

But green building designers are searching for more dramatic changes in cement options. "Let's ...begin to lessen the CO2 consequences of our current dependence on cement," said Gail Vittori, co-director of the Austin, Texas-basedCenter for Maximum Potential Building Systems, whose headquarters is built with concrete made from recycled sources. "Part of that is how we identify opportunities for some more-benign cement materials such as naturally occurring elements or recycled materials."

Alternative blends have included ash from coal-fired power plants, known as fly ash, and pozzolana, a volcanic ash. Although limited in their supply, these natural materials replace some of the fused minerals used in traditional cement, and therefore avoid the need to heat limestone to 1,450 degrees Celsius. The substitutes are becoming more common, mostly in continental Europe, according to the International Energy Agency.

Vittori said she is also keeping an eye on such companies as Calera. Even if they cannot replace cement entirely, their impact could be meaningful, she said. "Adding one percent here or there could make a big difference in CO2 emissions. It's certainly a worthy pursuit," she said.