The Science of Sustainability

Cement – A Dirty Business

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Thought California has consigned coal-burning to the scrap bin? Think again! California has 11 coal-fired power plants, all used to heat limestone into cement — making us one of the biggest cement-producing states in the country. In addition to cement, these kilns produce 95% of the state's airborne mercury pollution and 2% of its greenhouse gas emissions. Mostly, they've slipped under the radar of regulators, but that is changing fast.

You may listen to the "Cement – A Dirty Business" Radio report online, as well as find additional links and resources. Also don't miss our behind-the-scenes photos for this story.

Amy Standen is a Reporter for QUEST and Radio News at KQED-FM.

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Category: Energy, Environment, Health, Radio, Sustainable Health

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About the Author ()

Amy Standen is a radio reporter for KQED Science. Her email is and you can follow her on Twitter at @amystanden.
  • Joseph Holmes

    Clearly we need to figure out how to make cement without using fossil carbon as the heat source. Current indications are that we will be able to replace all of our ancient biofuels (coal, natural gas) with modern ones, and do so without severe consequences. A jet has been flown on biodiesel without engine modification. Biodiesel from tanks of algae may prove to be far cheaper than current fossil diesel. Cellulosic ethanol need not be made by taking unspoiled land and converting it to new agricultural land, rather from wastes from current tree farming and corn/wheat farming and similar sources, and should be cheaper than gasoline has been for some time. Look into it! Modern biofuels and superior efficiency can save our civilization from its insane dependence on fossil carbon and uranium 235.

  • Steve Greenberg

    Thanks for the report–it makes a number of important points. But one distinction that it doesn't make properly is the difference between cement (what's being made in the kiln) and concrete, which is comprised of cement binding together a variety of sizes of aggregate (typically from sand to gravel). Since most of the weight of the concrete is the aggregate, it is certainly not correct to use the terms interchangeably when talking about per capita use. At the beginning of the story, the statistic of about 4000 pounds per person per year of cement is used; later in the story, the same number is used for the consumption of concrete.

  • Amy Standen

    Good catch! Cement and concrete are not interchangeable terms (in the piece, we call cement a "key ingredient" of concrete). And yet our intro makes precisely the mistake Steve points out.

    Thanks for spotting it, Steve. We're making the fix on our Web version and for future broadcasts.

  • G. William Walster

    Thanks for this great report.

    The single most important thing to be done to reduce the air pollution is to install wet scrubbers. This should be required for all cement kilns.

    What is the impact on newborns surrounding the Hansen operation from the 400+ pounds of mercury fowling our air?

    In a San Jose Mercury News article, which I can no longer find, it was disclosed that cement kilns "dispose" of mercury ladened ash from coal fired power plants, because the kilns do not have the same clean air requirements as power plants. Can you find out if the Hansen plant is "disposing" of ash from power plants?

    Finally, I learned that the Stevens Creek reservoir was constructed to supply water for the quarry and cement kiln, not for flood control. The water below the reservoir is full of sediment. Above the reservoir, it is crystal clear. Is the Hansen operation disposing of ash and/or other waste material in the reservoir and/or the creek below it? Stevens Creek contains endangered Steelhead trout. If the Hansen operation is fouling Stevens Creek, it should be fined and/or shut down.

    This blight on the City of Cupertino and surrounding cities needs to be cleaned up or shut down.

  • Deric Horn

    I'm glad someone is starting to raise awareness of this issue. The burning of fossil fuels and tires is in such a contrast to neighboring Silicon Valley.
    How many drivers would it take switching to hybrids to make up for the environmental impact of Hansons cement? How do they get away with this?