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High-Tech: Carbonized Corncob Storage for NatGas Vehicles

Would you believe ground up corncobs and natural gas do mix, and what's more they have a future in powering delivery trucks around the country? That's according to Missouri University's (MU) Office of Technology Management and Industry Relations (TMIR), which recently negotiated an agreement for the manufacture of natural gas tanks made of carbonized corncob briquettes, nicknamed "Missouri hockey pucks," using a process developed by university researchers.

The agreement gives ANG Containment and Delivery Systems, a Wyoming firm, a worldwide exclusive license to produce high-surface-area carbon from corncobs for ground transportation vehicles. The initial goal of ANG is to start using the briquettes in natural gas tanks within the next year.

The company said it will use the technology to replace the gasoline fuel tanks in food and beverage delivery vehicles, garbage trucks, box trucks and short-haul semis with natural gas tanks. Currently these vehicles are some of the highest emitters of greenhouse gases. Using natural gas in this sector can reduce greenhouse gas emissions by 90%, while yielding diesel-level torque. The developers claim that natural gas-powered vehicles are comparable to equivalent conventionally fueled vehicles in overall performance, horsepower, acceleration and cruise speed.

The agreement stipulates that the first production plant must be built in Missouri, which has a lot of leftover corncobs.

David Pape, ANG's executive officer, said the technology addresses many of the disadvantages of using higher pressure compressed natural gas (CNG), such as the expensive infrastructure required for filling stations, safety in collisions and integration into existing vehicle designs. The system uses a patented carbon filler that acts like a sponge, chemically holding certain gases close together without high pressure.

Through their research, the MU team found that corncob carbon briquettes had a very large amount of surface area, capable of storing natural gas at much lower pressures and in greater quantity than current technologies allow. The surface area inside a carbon briquette, which is approximately 3.5 inches in diameter and 1.5 inches tall, is equal to about 60 football fields. When "activated" they develop a space-filling network of nanopores that can hold methane at a high density without the cost of extreme compression.

Until now, standard CNG systems have used high-pressure natural gas that has been compressed to a pressure of 3,600 psi (recently increased from 3,000 psi) and heavy-duty cylindrical tanks that can take up the space of an entire car trunk or storage area.

The ANG storage systems store the fuel at a pressure of only 500 psi, the pressure found in natural gas pipelines. The low pressure of 500 psi is key to the ability to craft the tank into any desired shape, so fuel storage tanks can be thin-walled, slim, rectangular structures affixed to the underside of the vehicle, rather than taking up room in the vehicle.

The natural gas can be injected into the new material using a centrifugal gas pump, which is much less expensive than the multi-stage piston compressors required by CNG tanks. ANG tanks can be filled by existing high-pressure fueling stations with a pressure sensing adaptor. When the tank reaches 500 psi the sensor stops the filling pump, using the same circuit shut-off currently in place with just a different pressure setting.

The technology vital to making this a reality was developed by Peter Pfeifer, professor and chair of the MU Department of Physics, and Galen Suppes, professor of chemical engineering. Pfeiffer and Suppes led a team of researchers, including Carlos Wexler, associate professor of physics at MU, who have been involved with ongoing research associated with this project.

"For the same amount of energy, combustion of natural gas produces significantly less CO2 [carbon dioxide] than combustion of gasoline, reducing the production of greenhouse gases," Wexler said. "Ultimately, hydrogen-fueled cars are the goal, but natural gas can serve as a stepping stone to move the economy in the direction of hydrogen by setting up natural gas fuel stations and pipelines, which could be later converted to hydrogen."

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