Sunday, Jul. 06, 2008

Daniel Weintraub: Here's concrete way to make state greener

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California's historic attempt to put an entire state on a low-carbon diet as a way to stave off global warming is going to reach into every corner of the economy, changing the way we live, what we drive and many of the products we use every day without ever thinking about their origins.

The scope of the effort is just now coming into focus, and as it does, it is becoming clear that the state's goal – reducing the emission of greenhouse gases by about 25 percent by 2020 – is going to be difficult and, probably, expensive.

At the same time, the pressure to cut emissions might also lead to new technologies and new ways of doing things that could be cheaper and better. Consider cement.

Call The Bee's Daniel Weintraub, (916) 321-1914. Readers can see his California Insider political blog at CapitolAlert.com

Cement is crucial to the state's economy, literally paving the way for the growth that creates and preserves jobs. It is in our roads by the ton. It is underneath and, increasingly, within our houses. It is part of the backbones of our factories, stores and office buildings.

Californians will use more than 12 million metric tons of cement this year – nearly one-third of a ton for every man, woman and child in the state.

But there is a problem. The production of cement creates a lot of carbon dioxide, the gas scientists believe is causing the temperature of Earth's atmosphere to rise. The 11 cement plants in California produce about the same amount of CO2 every year as 2 million passenger cars driven on the state's roads.

Cement comes from limestone, which is mined, crushed and then heated in kilns at temperatures above 2,700 degrees Fahrenheit. As the temperature rises, calcium carbonate is transformed into calcium oxide, or lime, which is the key ingredient in cement. In chemical terms, CaC03 becomes CaO + CO2. The difference between limestone and lime, then, is the freeing and release of carbon dioxide.

For every ton of lime produced for cement, nearly a ton of carbon dioxide is produced as a waste product. You cannot have one without the other.

Cement makers say that 57 percent of the C02 that comes from their plants is a result of this process known as calcination. Most of the rest comes from the burning of fuel, often coal, to create the intense heat needed to transform the limestone into lime.

The Air Resources Board, which is leading the state's attempt to reduce the spread of greenhouse gases, has the cement industry in its sights. The board listed cement among the potential "early actions" that could be taken to reduce carbon dioxide production, and again fingered the product in its recent outline of the approach the board intends to take in the months ahead. But so far the regulators have not said exactly what they plan to do.

One reason might be that there are no easy answers.

The state could force the cement makers to reduce the amount of energy they use in their plants. But the manufacturers say they have already done that. Energy costs money, and no company likes to spend money needlessly, especially in an industry as competitive as cement. So they have been working for decades to reduce their energy consumption.

The state could order the plants to use different fuels as a heat source, or to use more efficient equipment that creates less CO2 in that part of their process. But if those changes drive up the cost of making cement in California, cement from elsewhere – Nevada, Utah, even China – could become more competitive. And if imported cement replaces California cement, the result could be more greenhouse gases, not less.

The only sure way to significantly reduce the amount of carbon dioxide that comes from the use of cement, then, is for Californians to use less cement. That means using less concrete, which consists mostly of cement, sand, gravel and water. But the state is expected to use more, not less concrete in the years ahead, as the population grows and as the government rebuilds roads, highways and levees as part of a huge drive to repair and expand California's infrastructure.

As a result, engineers have been exploring the possibility of reducing the amount of cement typically used in concrete. Interestingly, they have found that they can substitute alternatives for cement and get a concrete that is as strong or stronger than the traditional recipe.

One of those alternatives is fly ash, a byproduct of the burning of coal in power plants. Another is slag, which comes from the production of steel. A recent study by the State Transportation Department found that either could be substituted for cement in large amounts. Some of the concrete used in the reconstruction of Interstate 5 through Sacramento this summer was 50 percent slag.

The push to reduce greenhouse gases, in other words, could reduce the need for lime, cut energy consumption and create new demand for the recycled waste products of some of the world's dirtiest industries.

If that is the way it plays out, both the environment and the economy would be winners.

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