Technology▼Solutions Gobbling up waste to produce fuel oil
CHANGING WORLD TECHNOLOGIES, INC. & AFFILIATE COMPANIES © 2003
neer Donald White, an emeritus professor at the University of Arizona, Let’s talk turkey. Changing World blue sky optimists who foresee a carTucson, says that such projects have Technologies (CWT), a privately held bohydrate economy that could a lot of potential; however, biomass company based in West Hempstead, thumb its collective nose at Middle energy applications will not be able N.Y., is perfecting a recipe for transEastern oil to cynics who wonder if to compete directly with coal, petroforming the leftovers from Butterball the only turkeys that CWT will ever leum, or natural gas sources, at least turkeys into commercial-grade fuel process are the big investors and not in the next 10 years. Alvin Weiss, oil. The company is collaborating government moneymen. an emeritus professor at Worcester with food giant ConAgra to Polytechnic Institute in Worcesopen its first commercial wasteter, Mass., and a veteran of the to-energy plant in Carthage, energy crisis, also worries that Mo., which is scheduled to go CWT’s hype may exceed its on-line by the end of the year. abilities. The Carthage plant will be the CWT’s process, called therfirst in the world to use waste to mal depolymerization, uses produce fuel oils that are practiwater, heat, and pressure to liqcally identical to natural hydrouefy waste such as turkey biocarbons. mass and is based on a concept The idea of producing energy that isn’t new, according to Tony from biomass or waste is hardly Bridgwater, who heads the Bionew, but most alternative energy energy Research Group at Aston technologiesincluding biodieUniversity in Birmingham, U.K. sel, gasification, and pyrolysis Pilot plants tried this approach have remained sidelined bein Albany, Ore., in the 1970s and cause of technical and economic Manchester, England, in the barriers. The gizzard wizards at 1980s. In The Netherlands, a CWT claim to have a commersimilar process called hydrocially viable solution. In fact, thermal upgrading is heading they boast that they can gobble toward commercialization as a up practically any waste made of niche technology (see “Biofuels carbon—tires, plastics, sewage go Dutch” on p 390A). sludge, paper, animal, medical Economic barriers stand in waste, and agricultural refuse— the way of successful large-scale and turn it into oil. The compacommercialization, says Bridgny also points out that recycling water, adding that he doesn’t materials already in the terrestriknow of any recent innovations al carbon cycle limits global that could make things dramatiwarming. Moreover, turning docally different. mestic waste into oil contributes However, chemical engito energy independence. neer Jefferson Tester, who heads The process and the claims MIT’s Energy Lab and is one of have attracted some sizable the few experts who has visited This waste hopper is where low-value organic feedamounts of cash. Private inCWT’s pilot plant in Philadelstocks like the waste from Butterball turkeys are slurvestors have contributed about phia, Pa., thinks the idea holds ried with water to begin the process that transforms $30 million, and the U.S. Deenormous promise. This plant, them into high-value energy products. partment of Energy and the U.S. which opened in 1999, can proEPA have granted $12 million. The Could CWT really convert the cess 7 tons of organic material a day. idea has also captured the imaginaUnited States and other countries to Tester says the process delivers as tion of some well-known people, a carbohydrate economy? Many scipromised on this relatively small from financiers to senators to former entists and engineers who have been scale, but a full-size plant is the big CIA heads. CWT has also generated involved in biomass or waste-to-entest. “Until we see what happens in abundant online energy on various ergy projects since the 1970s energy Carthage, there are still many unreInternet lists. Opinions ranged from crisis are skeptical. Chemical engisolved questions,” he says. © 2003 American Chemical Society
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CWT chose the Carthage site for its first full-size plant in order to be nearby the facility where ConAgra’s Butterball Turkey Company slaughters 30,000 turkeys each working day. Every day, the $20 million plant is expected to convert 210 tons of turkey waste from one of America’s favorite brands, together with 30 tons of cooking grease, into 70 tons of crude oil. CWT’s oil is chemically similar to a mixture of diesel fuel and gasoline and should sell for about $15 a barrel. It costs $5–13 a barrel to drill for oil, according to CWT chief technical officer Terry Adams. The oil is practically identical to petroleum products, and it can be directly mixed or substituted for them, Adams says. In addition to the 70 tons of oil, the CWT process generates 7.5 tons of clean methane; 6.7 tons of absorbent carbon, such as activated carbon; 8.2 tons of dry minerals; and 33.6 tons of liquid fertilizer concentrate. CWT claims that the system produces no polluting emissions and that the only byproduct is 80 tons of distilled water. This is a far cry from the 1.3 million gallons of pretreated slaughterhouse wastes that Butterball currently discharges daily from its plant; according to a Sierra Club report, the facility has violated pollution limits many times. The key to a competitive price for CWT’s oil lies in finding markets for the other products, which Adams says he can rely on, and receiving an additional payment from ConAgra for disposing of the turkey waste. Without that revenue, CWT’s turkey oil would go for about $40 a barrel, according to Adams. The cost per barrel should decrease as the company builds new plants and improves the process, says Adams. CWT won’t reveal exactly how the process works. There have been no peer-reviewed papers and no conference talks. Adams is unapologetic: “This is a commercial enterprise. We want to keep the details secret because we are trying to make a buck on this.” Adams acknowledges the problems with similar processes but says that CWT’s approach is different. The trouble with most of these other technologies, he says, is that they rely on a one-step process that either “produces rotten products or that costs too much.”
Biofuels go Dutch In 1999, when CWT’s pilot plant for converting wet waste into fuel was starting up in Philadelphia, Pa., a similar pilot plant was commencing operations in The Netherlands. Biofuel B.V.’s continuously operating hydrothermal upgrading (HTU) pilot plant in Castricum uses a process similar to the first step of the CWT technology to convert a wide range of biomass residues to “biocrude”, a 10% oxygen oil that can be burned instead of coal in power stations. Cost estimates show that future plants can produce biocrude for about the same price as coal. Biofuel B.V. can also make a diesel fuel substitute that can be mixed with traditional diesel. The HTU process produces up to 80% of its output as an oil that can be converted to high-quality kerosene and diesel analogues, according to Biofuel engineer Frans Goudriaan. He estimates that the Biofuel will be sold at a price competitive with crude oil. Unlike CWT, the Dutch scientists aren’t afraid to give talks or publish papers about their plans. They’ve been speaking at biomass conversion conferences since the late 1990s. Biofuel is hoping to market its diesel substitute by 2010 and estimates that HTU diesel could replace 5% of the fossil diesel fuel in The Netherlands by 2020.
CWT gets around the problem by combining three well-established technologies. Here’s what happens. The turkey remains and fat are put through grinders and mixed with water to make a paste that is similar in consistency to peanut butter or pumpkin pie filling. This paste passes into a reactor where it is heated to 260 °C at 50 atmospheres (735 pounds per square inch) of pressure. The mixture stays in the first reactor for 15–60 minutes, during which the fats are hydrolyzed to fatty acids. This step is akin to the Colgate–Emery processes used by renderers. The bones form a gritty flour that sinks to the bottom; at this point, the oil looks and smells “burned”. Next, CWT flashes off the steam and recovers the heat, which also removes about half of the water. Then the materials are separated by a centrifuge. The remaining water contains nitrogen and other minerals and proteins, which can be sold as a highquality liquid nitrogen fertilizer, similar to “fish solubles”, says Adams. The burned oil, which like most biomass- and waste-derived fuels has a high oxygen content, goes into a coker where it breaks down to a light oil and methane that can be used to operate the plant. Adams says that for every 100 BTUs in the feedstock, they use only 15 BTUs to run the process. The ConAgra–CWT joint venture plans to construct plants next to other ConAgra facilities to make oils from leftover chicken parts and onion husks. Negotiations are also under
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way for a 200-ton-per-day plant in Italy, and the City of Philadelphia gave the company a $50,000 contract to study how to turn the city’s sewage sludge into fuel. Adams makes fewer promises about the economic viability of this sewage sludge venture—just getting rid of the waste and the risk of pathogens would be solving the problem, he says. But Adams and others note that many recent worldwide developments seem to favor this new wasteto-energy approach—particularly for the waste from the meat industry. “This is not an incremental change. This is a big, new step,” says Alf Andreassen, a principal of Paladin Capital Group of venture capitalists who have invested in CWT. “In Europe, there are mountains of bones piling up” because of new regulations for handling bovine spongiform encephalopathy, or mad cow disease, he says. “When recycling waste into feed stops in this country, it will change everything,” he adds, referring to the still common practice of adding animal wastes to animal feeds. Says MIT’s Tester, “Look at the amount of energy we use to feed 280 million people, and half of that is waste—either rendered, left to rot on fields, or burned. This could be the first step toward a win–win situation, and maybe the time is right for this right now. The success or failure of the Carthage plant will resolve most of the questions.” REBECCA RENNER
PNNL
Measuring knuckle cracks In late August, researchers at the Pacific Northwest National Laboratory (PNNL) in Washington state completed prototype testing of a robotic system that gives new details about the structural integrity of the tanks used to store hazardous waste at the U.S. Department of Energy’s nearby Hanford site. Hanford’s 177 underground storage tanks hold 53 million gallons of nuclear and chemical waste, and some of it is leaking into the local groundwater. The first tanks, built as early as the 1940s, were single-walled, but their contents have since been emptied into sturdier, double-walled tanks. Government regulations mandate that these double-walled tanks be inspected, but no technology was previously available to “see” the crack-prone “knuckle” region near the bottom of the tanks where the wall meets the floor. PNNL
The remotely operated nondestructive examination (RONDE) system, shown here on a tank in a laboratory, uses ultrasound to image the highly stressed “knuckle region”.
61-cm Riser
Secondary tank
Primary tank
Tank knuckle Transition weld
Concrete
The “knuckle” is the weakest part of the tank and difficult to assess. Researchers send RONDE down the riser with a camera so they can see where to attach it on the primary wall.
PNNL’s new remotely operated nondestructive examination (RONDE) system examines the knuckle with ultrasound, which has been used to inspect the tanks’ walls. Working out the logistics to image the highly stressed knuckle curve was complicated, says Alan Pardini, RONDE project manager. RONDE spots cracks in the knuckle region from up to four feet away. To
do that, the system uses a transducer that sits on the primary tank wall in an accessible area, which is located in the space between the two walls, and introduces sound waves that spread and bounce back to create a picture of the knuckle, making any cracks “visible”. For the initial examination, transducers move across a 12-inch section in about 15 minutes. “If we find a crack, then we go back and do a more rigorous slow-down, take-your-time, make-sure-you’re-not-missing-anything type of a scan,” says Pardini. This next step requires a synthetic aperture focusing technique (SAFT), which is signal processing that creates high-resolution images. These images provide information on the location and length of the crack. To estimate the depth of a crack, researchers use tandem-SAFT processing whereby two transducers “pitch and catch” signals between each other. Pardini expects the final version of the RONDE system to be operational by the end of this year, and he acknowledges that the system has room for improvement. “At this point, all we can do is detect and size the cracks,” says Pardini. The researchers intend to expand RONDE’s capabilities so that it can characterize other degradation mechanisms, such as general and localized corrosion. —RACHEL PETKEWICH NOVEMBER 1, 2003 / ENVIRONMENTAL SCIENCE & TECHNOLOGY ■ 391 A
