Concrete is an energy hog, but at least it’s produced locally.
Thursday, January 31, 2008
Like it or not, climate change laws are coming to California. And in the face of the inevitable, even the biggest greenhouse gas emitters are painting their products green.
The Association of Monterey Bay Area Governments held a conference Friday, Jan. 25, at Seaside’s Embassy Suites to discuss the impacts of the state’s new climate change policies on the regional economy. While companies showcased their eco-savvy products in the lobby, policymakers and businesspeople grappled with the implications of AB 32, which mandates a 25 percent reduction in the state’s greenhouse gas emissions by 2020.
Attendees may not have been surprised to hear from Pacific Gas & Electric, the goliath utility company. Less predictable was a presentation vouching for concrete, one of the world’s most energy-intensive products.
Graniterock Company, a Central Coast-based building materials supplier, is marketing its locally-made concrete as a green product that’s long-lasting, made with recycled products and recyclable. “Roads and buildings should be supplied locally, because that way we know that they were produced using environmentally sound practices,” says Aaron Johnston-Karas, the company’s sustainable resource development director.
But a top expert who wasn’t at the conference says it’s not that simple. “These guys are paid to tell you all the wonderful things about concrete,” says Hendrik van Oss, a cement specialist for the U.S. Geological Survey. “Concrete can be environmentally friendly from a point of view of longevity and fire resistance. On the other hand, the cement component is pretty energy-intensive, and it’s a big CO2 emitter.”
Cement, produced by crushing and heating a mixture of mined clay and limestone, requires a huge amount of fossil fuel energy. Each ton of clinker – the intermediate product in the cement manufacturing process – emits nearly its own weight in carbon dioxide, van Oss says. The cement industry coughed up about 2.5 billion tons of CO2 in 2006, about 5 percent of the world’s non-agricultural total.
While China produces about half of the world’s cement, California’s share is less than one half of 1 percent. But that’s still a heavy carbon footprint, at 11.4 million tons of CO2 – roughly equivalent to tailpipe emissions from 1.8 million new Honda Civics in an average driving year.
Graniterock and other concrete manufacturers make cement greener by adding fly ash from coal-burning power plants and slag from iron blast furnaces. The additives are an eco-trifecta: recycling industrial waste, strengthening the concrete so it lasts longer, and reducing the proportion of energy-intensive cement in the final product.
Transportation of ingredients also plays a role; the fewer miles traveled, the smaller the carbon footprint. Graniterock makes concrete with rocks from local mines and cement from the Bay Area, though the industrial additives come from out of state. Other concrete makers use imported Canadian rock and cement from Mexico or China, Johnston-Karas says.
Graniterock also offers pervious concrete, which cuts carbon indirectly by allowing rainwater to percolate into soil rather than running off as stormwater. Though it hasn’t been used much locally, the technology has the potential to recharge aquifers and irrigate vegetation without using fossil fuel energy.
By identifying eco-friendly components, Graniterock positions its products to earn points through the Leadership in Energy and Environmental Design rating system, which sets the standards for certified green building. The company even has three LEED-accredited experts on staff. “People who are going to be really proactive about building green and building sustainably need to understand more than what’s on the surface,” says spokesman Keith Severson.
But green building math gets fuzzy.
Johnston-Karas argues that concrete is a lower energy user than wood because it can last hundreds of years. But van Oss points out that concrete tends to crack and erode, especially in earthquake-prone regions like California. Most cement-based structures are demolished within decades, not centuries.
However, concrete recycling is gaining popularity. Graniterock crushes and re-uses chunks of jacked-up sidewalks, driveways and parking lots. Monterey Regional Waste Management District diverted more than 22,000 tons of concrete and asphalt from the landfill last year, which Salinas-based Don Chapin Company turned into gravel for road building, according to district spokesman Jeff Lindenthal.
Eco-friendly tweaks like those made by Graniterock do add up to carbon savings. But they aren’t the dramatic change scientists say are needed to slow the pace of global warming. Graniterock’s local branch manager, Mike Chernetsky, admits California’s new climate laws are unlikely to overhaul the company’s energy-intensive operations. “We’re running business based on what the public wants and what the consumers are asking for,” he says.
Ultimately, van Oss infers a possible political motive in concrete manufacturers’ green marketing. “The cement industry wants [power] plants to have the ability to operate at full blast,” he says. “Their biggest fear is that a policy will be enacted that will be aimed at the power plants, and that will utterly devastate the cement industry.”