Bay Area Cement Plants and Global Warming
Filed Under: US | Posted: 12/16/2008 at 2:45PM
Comments | Region: California | United States
Article by Chris Amico
CUPERTINO, California–From the lip of the quarry at Hanson Permanente cement, all of Santa Clara stretches out in panorama. (Photos here).
Few plants in California are this close to this many people. Most of the state’s 11 kilns are well away from population centers, close enough for workers to commute, but otherwise out of sight.
Here, houses reach right up to the edges the Permanente land, where suburban homes suddenly give way to an industrial road leading up to the expansive plant and the limestone mining operation behind it.
Here, engineers and executives will have to figure out how to make an essentially dirty process clean, or at least cleaner.
As California tries to fight global warming–with or without the rest of the country–cement manufacturing remains one of the trickiest industries to regulate.
"I don’t think there’s anybody quite like cement," said Mike Tollstrup, one of the state officials overseeing California’s effort to fight global warming on its own. "There are not a lot of facilities. Cement is used everywhere. There are significant issues of leakage. If we don’t do it right, the potential for increasing emissions is a real concern."
In 2006, California adopted Assembly Bill 32, a law mandating that by 2020, the state cut greenhouse emissions to 1990 levels. The California Air Resources Board, which will oversee implementation, released a Proposed Scoping Plan at the end of October mapping out how the state will reach its goal.
Cement is one of the industries singled out by regulators because, as Tollstrup says, it’s both necessary and necessarily polluting.
Unchecked, carbon emissions from the cement sector would rise 23 percent, from 9.7 million metric tons in 2004 to 12.6 million metric tons in 2020, according to state statistics.
Demand for building materials moves in concert with population growth, and California’s population continues to grow. By 2030, the US Census projects it will exceed 46 million people.
"Long term trends look promising if you’re a cement maker," said Andy O’Hare, vice president of regulatory affairs for the Portland Cement Association. "First and foremost, any economy is going to need cement from somewhere to continue to grow. We’re working from that premise, and state government seems supportive."
(Cement and concrete are different things. Concrete is a blend of materials–cement, fine and coarse aggregates, water–that harden into a firm structure. Cement is the glue holding it all together. In dry form, it’s a chalky powder.)
At every stage of cement production, there is something to evoke an environmentalist’s worst nightmare.
It starts with limestone. Behind the Permanente plant, an open quarry funnels down 750 feet into the Santa Clara hillside.
Twice a week, mining crews detonate a series of explosives set into the rock face. Water trucks hose down the loose gravel, weighing down dust.
Raw ore moves by conveyor belt through grinders until each chunk reaches a uniform size, about a cubic centimeter.
Turning limestone into lime is the main source of carbon emissions. The mined rock must be heated to 2,700 degrees Farenheit. That uses massive amounts of fuel.
The most common fuel in cement plants is coal, though Permanente doesn’t use it. This plant relies entirely on petroleum coke, a byproduct of oil refinement. Pet Coke isn’t any better for the air than coal (chemically, it’s similar), but it disposes of otherwise troublesome waste.
Heating limestone turns it into lime, releasing carbon dioxide in the chemical reaction.
What comes out is called clinker. It’s ground into a fine powder and stored, to be mixed with water, sand and gravel to become concrete.
For data visualization of the graph below go here.
Fuel types for making cement
Emissions targets and the intensity standard
The oft-cited measure of cement’s impact on global warming is one ton of carbon dioxide for every ton of cement produced. California plants, on average, are about 10 percent cleaner, putting out only .895 tons of CO2 for each ton of cement. The state would like to see that number drop to .80.
The danger, say all involved, is that cement production could shift out of state. While California’s plants continue to clean up, if their products become too expensive, local builders could make up costs by buying more cement from out of state, negating any emissions gains made here. At the moment, China is the biggest supplier of imported cement, as well as the world’s largest source of greenhouse gases.
To combat leakage of production, the AB32 scoping plan proposes to apply a carbon intensity standard to all cement sold in California, not just what’s produced here. When measuring the carbon footprint of imported cement, regulators say they would count every part of the process, from mining to calcination to shipping.
Manufacturers see this as the best part of the state’s plan. Putting a cost on carbon means shipping cement from China counts against importers. Counting the 20 percent increase in emissions resulting from transport, California kilns maintain an edge.
California consumes more cement than it produces, so some cement is always imported. In a good year (which 2008 is not), the state’s 11 kilns can put out 12 to 13 million metric tons of cement a year. Public and private builders use as much as 16 million metric tons.
"We think that we can set limits that would apply to out of state (and out of country) facilities, too. That way everybody has that requirement," Tollstrup said. "If you want to sell cement in the state of California, you have to meet that requirement."
California has done this before, Tollstrup said, pointing to the rule that all gasoline sold in the state must contain an oxygenator–a requirement that led refiners to add MTBE, and later ethanol to fuel blends.
But the state tried applying local emissions standards to automobiles, too, provoking a multi-year fight with the federal Environmental Protection Agency and the Bush Administration, which tried to block California’s tailpipe rules. With George W. Bush about to leave office, though, Tollstrup is optimistic.
In theory, cleaning up will be good for business.
In 2020, according to an economic analysis of AB 32 commissioned by the Air Resources Board, the state’s economy will have:
- Increased production activity by $27 billion
- Increased overall Gross State Product by $4 billion
- Increased overall personal income by $14 billion
- Increased per capita income by $200
- Increased jobs by more than 100,000
For cement makers, better energy efficiency and smoother production processes should save money, the state says.
Industry-wide, California expects cement plants to save $3.4 million annually, spread over the next 12 years.
Diane Bailey, a research scientist with the Natural Resources Defense Council, said global warming is only part of the story. With cement production comes other pollutants besides, especially mercury.
"There’s more pressure than AB32 for kilns to clean up," Bailey said, pointing to a plant in Riverside being sued for chromium contamination. In Davenport, north of Santa Cruz, a Cemex-owned plant shut down earlier this month when the same toxin was detected in its exhaust.
Emissions by sector in California
Bailey would like to see cement plants switch to natural gas, a wish common among environmental groups and universally dismissed by the industry. Tollstrup, the state official, said it’s probably not practical, anyway. The infrastructure just isn’t there.
"A lot of these facilities are located where they don’t have access to natural gas," Tollstrup said. "You’ve got to bring in the fuel from somewhere else."
Use less cement
From the state’s perspective, there’s only so much that can be done to reduce cement’s carbon footprint. Roads and bridges built over the next decade may simply have to find alternative ways to make concrete.
Tom Pyle, an engineer with CalTrans, deals with such issues every day.
When CalTrans builds a bridge, he explained, it’s primary concerns are safety, structural longevity and cost. Solving global warming isn’t the agency’s goal (though Pyle counts himself an environmentalist). What he and other concerned builders have been trying lately is something that addresses both issues
In large scale projects, Pyle said, a common problem is alkali-silica reactivity, essentially rust that eats away at the strength of concrete. For a building, it’s a cancer
"One way to stop it is to put fly ash in," Pyle said. "From an engineering point of view, it’s a medicine that stops this cancer."
Fly ash is a byproduct of burning coal, so it’s not entirely clean, but many see it as a step toward cleaner building materials.
"We’re fortunate in that we don’t have to create anything new," Pyle said. "We already have a product in our toolbox we can use to make concrete, and in fact protect the concrete, and in fact reduce the CO2."
Statewide, Pyle estimates, most projects will only replace five to eight percent of cement with slag, fly ash or other materials, but those numbers are creeping up. And Pyle now has a grand example he can point to when pushing other engineers to build cleaner: the Bay Bridge.
The columns holding up the rebuilt span, parts of which collapsed during the 1989 Loma Prieta earthquake, use a cement made from 50 percent steel slag. Underwater, the cement is 60 percent fly ash.
"We did it for engineering reasons," Pyle said. "We can also do it for environmental reasons throughout the state, and that’s where we are headed."
Where the state would like to reduce the amount of cement used, the industry is trying to offset its damages.
At the Permanente plant, there is talk using the kiln’s leftover heat to generate electricity, something happening in other parts of the world, but which no other facility in California does.
"Back in the 40s, most cement plants created their own power, only because we didn’t have a stable utility sector," Shane K. Alesi, a Heidelberg executive, said.
O’Hare, of the Portland Cement Association, said his organization is working with scientists at Lawrence Berkeley National Laboratory to expand the use of concrete in home construction, which can save on heating bills.
"If taken to its full extent and applied, we expect the development of a model which could be used by urban planning communities in the future to minimize their climate footprint."
That’s something Pyle, of CalTrans, sees as well.
"I believe the cement industry is seeing opportunity," the engineer said. "As our world starts to change, we’re going to start to look for sustainability. To me, as a concrete geeky kind of engineer, sustainability means bulding things that are going to last more than a generation. And for CalTrans, what we’re looking at is extending life of our roads and bridges.
It’s hard to predict where the cement industry will be in 12 years. Emissions will probably be lower. If the state’s plan works out, those greenhouse gases will be gone, not just displaced.
Marvin E. Howell, director of land use planning at Hanson Aggregates (now also part of Heidelberg), said the big changes won’t occur at cement plants. Instead, AB 32 is "going to mean changes in how people use the product."
"Everybody is going to have to change," Howell said. "It’s not just us."
Tollstrup, the regulator, paints the most optimistic picture of the industry in 2020:
"I expect that the facilities in California will be the most efficient in the world," he said. "They’re just going to be ultra clean facilities by the we get to the end game here."