Lafarge cement plant reduced CO2 with biomass
"We recognize that our industry (cement) represents 5 percent of the world carbon emissions," said Robert Cumming, Lafarge environmental and public affairs manager. "There's also a very high demand for our products, for example, LEED (Leadership in Energy and Environmental Design) buildings use a lot of cement."
When initially embarking on the project, Lafarge had an agreement with biotechnology start-up firm Performance Plants, which provided its seed trait technologies for the planting of switchgrass, little bluestem, hemp, sorghum and tropical maize. Financial restraints forced Performance Plants to pull out of the project, according to Cumming, but Lafarge is still moving forward with its previous plans.
Last year, Lafarge began a multiyear life-cycle assessment study with Kingston, Ontario-based Queen's University's Energy and Environmental Policy Institute, and has been working closely with researchers on planting trials of perennial crops, utilizing about 2,500 acres of land surrounding the cement plant. Previously, Lafarge rented the land for agricultural purposes, but it was turned back over to the company when farmers could no longer use it. "Eastern Ontario doesn't have a very good agriculture industry because it doesn't host much class 1 and 2 land, mostly class 3 and 4, so biomass crops are a good fit here," Cumming said.
Lafarge has four fields set-aside for the trials, land on which the university has been performing various soil sample tests. "During this multiyear trial, we will try to confirm that we can get at least a 90 percent savings on CO2 by growing these crops," Cumming said. "It would be a 100 percent savings if we could use tractors fired by biomass. We're looking at carbon sequestration while root structures are being established in the first two years. We're hopeful that farmers, should this business (biomass crops) take off, will eventually earn some carbon or offset credits for such a land-use change. The only way that can happen is to have a scientific opinion to support it and that's what this is about-life-cycle assessments for purpose-grown crops-partly aimed at the long term, or when we begin to trade carbon credits. We want to earn rock-solid data, so there won't be any questions about what we're doing."
The second element to the Lafarge project will be testing and using the biomass crops as a fuel source. "Last summer, we contracted a number of local farmers to grow four different crops on the properties, all with different soil types," Cumming said. The harvest yielded 950 1,050-pound bales and now, Mesa Reduction Engineering and Processing Inc. out of Albany, N.Y., will provide equipment to process the bales before they are burned with the coal.
A forklift will be used to set the bales onto a conveyer belt, which will take them into a pre-shredder that will reduce them to chip size, and then through a grinder to produce a powdery material that will be blown pneumatically into the front end of the cement kiln. "We (the cement industry) use a lot of fuel," Cumming said. "Not nearly as much as the power industry but we're up there, and the reason we need so much energy is because we're heating rock up to almost a semi-molten level, about 1,400 to 1,500 degrees Celsius (2,550 to 2,730 degrees Fahrenheit)."
A typical kiln is cylinder shaped, about 18 to 20 feet in diameter and 650 feet long. "They're very large," Cumming said. "The front face of the kiln itself will be pneumatically blowing the powder into it with the coal and petcoke, the amount of which we use will be reduced."
During the tests, Lafarge will use up to 30 percent biomass, but a minimum of 10 percent. "Essentially we'll have the equipment there for a couple of weeks in early June, we'll then do a full emissions testing program to measure the effects and confirm the benefits of the fuel," Cumming said. To do that, Lafarge is working with emissions testing technology firm RWDI consulting, which will also perform tests using the plant's traditional fuel in order to produce data for comparison.
Cummin said the main impetus in the project as a whole is to stay ahead of the carbon emissions reduction game. "Lafarge has already reduced its CO2 emissions by 20 percent since 1990," he said. "In light of recent governmental commitments, we need to further reduce those emissions by about 18 percent, and what that means for the cement industry is more challenges than most because two-thirds of our emissions comes from converting limestone to lime." Ontario currently has a target of 20 percent reductions in greenhouse gas emissions from 2006 levels by 2020, which means Lafarge would have to replace nearly half of its fossil fuels with biomass, according to Cumming. "That  is only 10 years from now, and so we need to start work today to build the future," he said. "We recognize that carbon challenges are coming, and we intend to meet them head-on. We do have other possible solutions, but this one (biomass) is the most promising."