Farm Waste for Fuel Tanks

Julie Kalista
Online Editor

The biggest challenge for natural gas researchers has been meeting the 180-to-1 storage-to-volume target set by the U.S. Department of Energy (D.E.) in 2000.

Using corncob waste as a starting material, researchers at the University of Missouri-Columbia and the Midwest Research Institute created carbon briquettes with complex nanopores, that should meet the D.E.'s storage goal.

Current natural gas vehicles are equipped with bulky, high-pressure (compressed to 3,600 psi) tanks that take up the space of a trunk of a car. This new technology enables natural gas to be stored in smaller, low-pressure (500 psi -- the same pressure found in natural gas pipelines) tanks that can be shaped into a rectangular form and mounted under the floor of a car.

The researchers discovered that fractal pore spaces (spaces created by repetition of similar patterns at different scales) efficiently store natural gas. "This is the first time carbon storage materials have been made from corncobs, an abundant waste product in the Midwest," says one researcher. "The state of Missouri alone could supply the raw material for more than 10 million cars per year."

A test pickup truck, part of a fleet of more than 200 natural gas vehicles, has been in use since mid-October. Researchers are monitoring mileage range per fill-up, pressure and temperature of the tank during charging/discharging, charging/discharging rates under various fueling/driving conditions, and longevity of the carbon briquettes. The work could hold promise for hydrogen storage.

Natural Gas Vehicle Facts

Natural gas is one of the cleanest burning alternative fuels available.

In light-duty applications, air emissions from natural gas vehicles are lower than emissions from gasoline-powered vehicles. The smog-producing gases carbon monoxide and nitrogen oxides are reduced by more than 90 and 60%, respectively. The greenhouse gas carbon dioxide is reduced by 30 to 40%.

In medium- and heavy-duty applications, natural gas engines have shown a more than 90% reduction of carbon monoxide and particulate matter and, a more than 50% reduction of nitrogen oxides, relative to commercial diesel engines.
Source: U.S. Department of Energy, Energy Efficiency and Renewable Energy, Alternative Fuel Vehicles, http://www.eere.energy.gov/afdc/altfuel/gas_benefits.html

Most natural gas used in the U.S. is produced domestically.

In 2004, U.S. net imports of natural gas represented only 15% of the total amount used, with most imports coming from Canada.
Source: U.S. Department of Energy, Energy Efficiency and Renewable Energy, Alternative Fuel Vehicles, http://www.eere.energy.gov/afdc/afv/gas_vehicles.html

Natural gas is cheaper than gasoline and diesel on an energy-equivalent basis.

The national average cost of compressed natural gas (CNG) was 94 cents cheaper than gasoline on an energy-equivalent basis, according the Clean Cities Alternative Fuel Price Report in June 2006. Gasoline was $2.84 per gallon, diesel was $2.98 per gallon, and CNG was $1.90 per gasoline gallon equivalent (GGE).
Source: U.S. Department of Energy, Energy Efficiency and Renewable Energy report,http://www.eere.energy.gov/afdc/resources/pricereport/price_report.html

Natural gas can be produced from renewable sources like landfills.

As solid waste decomposes, it produces carbon dioxide and methane. Methane is the principal component of natural gas and can be harnessed by landfill gas energy stations and combusted for energy.
Source: Energy Information Administration, http://www.eia.doe.gov/cneaf/solar.renewables/page/landfillgas/landfillgas.html

Methane released into the atmosphere is more than 20 times more potent than carbon dioxide.
Source: U.S. Environmental Protection Agency, Landfill Methane Outreach Program, http://www.epa.gov/lmop/benefits.htm

Harnessing methane from all U.S. landfills is equivalent to removing the annual greenhouse-gas emission from 50 million cars, or planting forest on an area 2 times the area of Missouri every year. It could power 4 million homes or 4 million cars annually.
Sources: U.S. Environmental Protection Agency, Landfill Methane Outreach Program, http://www.epa.gov/lmop/res/calc.htm and http://www.epa.gov/lmop/gp/gp.htm; Additional calculations by Peter Pfeifer, MU professor of physics

Natural-gas fueled vehicles are comparable to conventionally fueled vehicles.

Horsepower, acceleration, and cruise speed in natural-gas-powered vehicles are comparable to conventionally fueled vehicles. About one of every five new U.S. transit buses is powered by natural gas.
Source: U.S. Department of Energy, Energy Efficiency and Renewable Energy, Alternative Fuel Vehicles, http://www.eere.energy.gov/afdc/afv/gas_vehicles.html

Table Source: University of Missouri-Columbia

More Information:
University of Missouri-Columbia
Midwest Research Institute

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