Thursday, September 11, 2008
Imagine three industrial plants working together to turn fossil fuels and seawater into electricity, cement and fresh water– while minimizing emissions and removing carbon dioxide from the atmosphere. It sounds too good to be true.
Yet if a Stanford professor’s theory works out in practice, a pilot facility in Moss Landing could become a global model for how power plants, cement manufacturers and desalination facilities can use each other’s waste to make all three processes greener.
Earth scientist Brent Constantz, who has founded two bone-cement companies, got the idea while working at Stanford University’s Woods Institute for the Environment. “I became aware that the production of Portland cement is the third largest source of the world’s carbon dioxide,” he says. “I realized that I could come up with much better chemistry that wouldn’t put CO2 into the atmosphere.”
With venture capitalist funding, Constantz founded Calera Corporation with an ambitious goal: to engineer a product that would not only emit zero CO2, but also sequester greenhouse gas pollution from power plants.
In effect, he proposes to reverse global warming by building.
How it works
Cement production accounts for about 5 percent of the world’s CO2 emissions– 2.5 billion tons in 2006, according to an industry report. During the manufacture of Portland cement, coal-fired kilns heat calcium carbonate (limestone) up to 3,000 degrees Fahrenheit, creating calcium oxide (lime) and CO2.
The Calera process, by contrast, takes a power plant’s waste CO2 and bubbles it through seawater. Naturally occurring calcium and magnesium in the water react with the CO2 to form mineral carbonates, which Calera separates from the water and dries using the power plant’s waste heat.
“The process is tricky, how you get from a liquid to a solid cement,” Calera Operations Director Sam Bose says cryptically. “We do all this secret stuff.”
Because the Calera process doesn’t involve heating limestone, Constantz says, it emits no CO2. Instead, it stores CO2 that would otherwise contribute to global warming.
The Dynegy natural-gas-fired power plant in Moss Landing emits almost 3.5 million tons of CO2 per year, Constantz says– roughly equivalent to Monterey County’s annual tailpipe emissions. If Calera is able to trap all of Dynegy’s CO2 in cement, it will be like taking all of the county’s cars off the road.
An ideal wasteland
The Moss Landing Commercial Park, a 200-acre property across from the Dynegy plant on Dolan Road, is a bleak industrial expanse without a blade of green. In the mid-1900s, the site was used to produce milk of magnesia for livestock and magnesium metal for World War II bombs. Later it became a Kaiser Aluminum refractory, producing insulation until going out of business in 2001.
Last spring, Calera leased a part of the commercial park and began test operations. For now, they’re using simulated flue gas to produce test batches of cement, according to Bose.
Engineers are also designing a pipe to transport waste heat from the power plant. Constantz hopes to tap emissions from 5 megawatts of Dynegy’s production (one-half of 1 percent of the plant’s 1,000-megawatt capacity) before expanding to full production.
Many of the refractory’s leftovers– windowless steel buildings, empty silos, round thickener tanks and 40 acres of dolomite and magnesium hydroxide waste– can be converted to Calera’s use, Bose says. He points out a pipe connecting to nine pumps on the ocean side of Highway 1, each of which can intake 4,000 gallons of seawater per minute. The pumps could provide much of Calera’s required 60 million gallons per day, supplemented by wastewater from the Dynegy plant.
Calera’s own wastewater might come in handy for the planned desalination facility next to the Dynegy plant. “Because we take the calcium and magnesium carbonates out of the water, it’s going to increase the efficiency of desalination by about 70 percent,” Constantz says.
Bose, who worked on the site first for Kaiser and now for Calera, surveys the stark landscape and shakes his head in wonderment. “I spent 30 years building this place, and then we tore it down, and now we are building it again,” he says. “This can turn into something that nobody ever imagined.”
Before Calera cement can save the planet, it must pass muster with building regulators and contractors. “The concrete industry is very conservative, for obvious reasons,” Constantz admits. “No one wants a bridge to fall down or a concrete slab to crack.”
Steve Kosmatka, vice president of research for the Portland Cement Association, says Constantz’s concept is nothing new; he’s just the first to market it. “Over the years I’ve seen many innovative cements in the research or development phase. Sometimes they’re successful; sometimes they’re not,” he says. “[Calera’s] concept is certainly feasible. We’ll just wait and see how well it works.”
Until the industry fully embraces his cement, Constantz hopes to market it as an additive that can be mixed with Portland cement to lower its carbon footprint. In February, he’ll make his case at the World of Concrete conference in Las Vegas.
But Hendrik van Oss, a cement comodity specialist with the U.S. Geologic Society, is skeptical. After a few impromptu calculations based on media reports of Calera’s process, van Oss figures the cement would be carbon-neutral at best– neither emitting nor sequestering net CO2.
The chemistry strikes van Oss as improbable. He doubts Calera could harvest enough seawater or waste heat to drive the manufacturing process. And even if it does work, he doubts the resulting mortar would be strong enough for roads or bridges.
“It’s an intriguing flow sheet. The devil might be in the details of how he does it well,” he says. “He will have to ride that chemical line carefully.”
Constantz imagines Calera cement factories neighboring power plants across America. His timing is opportune: California has mandated a reduction in power plant emissions, and Congress may soon consider a cap-and-trade scheme that could force power plants to pay for their CO2 emissions.
But Marcia McNutt, CEO of the Monterey Bay Aquarium Research Institute, sees a major hurdle. The California Coastal Commission wants to sunset the Dynegy power plant’s once-through cooling process– which can harm animals in the neighboring marine sanctuary– and replace it with re-circulated water. “That won’t do Constantz any good at all, because he can’t then mine the calcium and magnesium out of the [discharged] seawater for the cement process,” she says.
Even if Calera uses the former refractory’s seawater intake permit– which McNutt doubts would provide enough water for full production– it will need to obtain additional environmental permits.
McNutt acknowledges that Calera’s negative impact on the local marine environment might pale in comparison to the global benefit of carbon sequestration. But as far as permitting goes, that doesn’t matter. “The way the sanctuary regulations are written, they do not allow for that kind of argument,” she says.
If Calera cement succeeds, Monterey County Chief Administrative Officer Lew Bauman sees local benefits beyond sales tax revenue. “An abandoned asset of the county would be turned into a landmark environmentally friendly industrial facility,” he says, “and it would lower the carbon footprint of the county.”