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The MU-MRI low-pressure natural gas tank uses carbon briquettes
made from corncobs to store natural gas. Illustration
by Nicolle Rager Fuller, National Science Foundation
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New
Automotive
Tank Holds Promise
for Future
By Katherine Kostiuk
Researchers at the University of Missouri-Columbia
(MU) and Midwest Research
Institute (MRI) are testing an innovative alternative fuel
technology in a pickup truck owned and operated by the Kansas
City Office of Environmental Quality. This technology may
revolutionize the capacity of natural gas to power vehicles.
Current natural gas vehicles are equipped
with bulky, high-pressure tanks that take up premium cargo space,
such as the trunk of a car. This new technology, however, enables
natural gas to be stored in a smaller, low-pressure tank that
can be shaped into a rectangular form and mounted under the floor
of a car. What makes this possible is an MU discovery that fractal
pore spaces (spaces created by repetition of similar patterns
at different levels of magnification) are remarkably efficient
at storing natural gas. The scientists found a way to “bake”
corncobs into carbon briquettes that contain fractal pore spaces
and then use the briquettes to store natural gas in a low-pressure
tank. MU and MRI researchers are now testing a prototype of this
tank in the Kansas City pickup. They hope this will lead to the
design of low-pressure tanks that solve the cargo space problem
posed by high-pressure tanks.
“This technology could make natural
gas an attractive alternative fuel for smaller vehicles,”
said MU Chancellor Brady Deaton. “The research partnership
here exemplifies how scientists from very different fields can
work together to conduct truly fundamental research in new materials
with the explicit goal of having the results of the research solve
problems for people.”
The test pickup has been on the road since
mid-October. Researchers are monitoring the technology's performance
by collecting data to evaluate the 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. 

MU and MRI researchers are now testing a prototype of their
tank in the above pickup truck. They hope their work will
lead to the design of low-pressure tanks that solve the
cargo space problem posed by high-pressure tanks. Photo
courtesy of the Midwest Research Institute
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“Having a prototype of this technology
operating in the day-to-day work environment is significant,”
said James L. Spigarelli, president and CEO of the Midwest Research
Institute. “It symbolizes the power of collaboration and
the ability of MU and MRI researchers, working together, to make
a scientific discovery; to transfer that discovery to a technology,
in this case a fuel tank technology; and then move that technology
closer to commercialization. Although the team's work is not yet
complete, this technology development comes at a fortuitous time
as many researchers strive to find multiple alternatives to address
the nation's energy challenges.”
Kansas City has been a leader in natural-gas-powered
vehicles, ranging from utility trucks to shuttles at the Kansas
City Airport. The city operates more than 200 natural-gas vehicles
under the supervision of Central Fleet Manager Sam Swearngin,
who has been instrumental in forging this venture between Kansas
City and the MU-MRI team.
“The City of Kansas City is the undisputed
champion of alternative fuel vehicles in this region, and we are
pleased to have the opportunity to be on the ground floor of this
developing new technology,” said Kansas City Mayor Kay Barnes.
This project was funded by a $600,000 grant
from the National Science Foundation's
program Partnerships for Innovation, which has the goal of stimulating
the transformation of knowledge created by universities into innovations
that create new wealth, build strong local, regional and national
economies and improve the national well-being. Additional funds
totaling more than $400,000 came from MU, MRI, the U.S.
Department of Energy and the U.S.
Department of Education.
A secondary goal of the Partnership for Innovation
is to meet the broad work force needs of the national innovation
enterprise. The collaborative effort between MU and MRI has afforded
a number of university students the opportunity to receive hands-on
training for a career in research and development. As a result
of the exchange, MRI recently hired an MU graduate and a Lincoln
University graduate associated with the project team.
The MU-MRI collaborative is part of a larger
cooperative effort called the Alliance for Collaborative Research
in Alternative Fuel Technology (ALL-CRAFT), which includes partners
Lincoln University; DBHORNE, LLC; Renewable Alternatives, LLC;
the Missouri Biotechnology Association; the Clean Vehicle Education
Foundation; the Missouri Department of Natural Resources; and
the City of Columbia, Mo. ALL-CRAFT also worked in cooperation
with the Kansas City Regional Clean Cities Coalition (KCRCCC).
MRI is an independent, not-for-profit research
organization with 1,800 employees nationwide. Established in 1944,
MRI performs research for government and industry in national
defense, energy, life sciences, engineering and other areas. With
headquarters in Kansas City, MRI also has facilities in Palm Bay,
Fla., Frederick, Md., and Rockville, Md. MRI has managed the National
Renewable Energy Laboratory (NREL) in Golden, Colo., for the U.S.
Department of Energy since 1977.
MU-MRI Low-Pressure Tank Fact Sheet
- The MU-MRI low-pressure natural gas tank
uses carbon briquettes made from corncobs to store natural gas.
The walls of the nanoporous carbon adsorb methane molecules
as a high-density fluid. The strong attractive force in the
narrow pores lowers the energy of the molecules so that they
can be packed much more closely than in the absence of the carbon.
Such a tank is called an adsorbed natural gas (ANG) tank.
- The carbon briquettes can store 180 times
their own volume of natural gas, or 118 g of methane per liter
of carbon, at 500 pounds per square inch (psi). The best previous
carbon could only store 142 times its own volume at 500 psi
pressure. The target set by the U.S. Department of Energy is
180 times the storage a material's own volume. The MU-MRI carbon
reaches this target for the first time.
- A conventional high-pressure natural gas
tank operates at 3600 pounds per square inch (psi), whereas
this low-pressure tank operates at 500 psi. This enables flexibility
in tank design because high-pressure tanks require bulky, cylindrical
walls, whereas the low-pressure tank can use thinner walls in
a variety of shapes. The pressure of 500 psi equals the pressure
in natural gas pipelines, which eliminates costly compression
of natural gas from 500 psi to 3600 psi in CNG tanks.
- The technology being tested in this tank
would enable car manufacturers to design long, slim, low-pressure
tanks to replace the bulky high-pressure tanks in current natural
gas vehicles. This would enable them to place the tank underneath
the body of the car, whereas the high-pressure tanks are usually
placed in a car's trunk, reducing vehicle cargo space.
- Corncob is an abundant, low-cost, renewable
raw material in the Midwest, allowing for production of ANG
tanks from domestic sources. The state of Missouri alone could
supply the raw material for ANG tanks of 10 million cars per
year. Corn could thus serve the alternative fuel economy in
two distinct ways - corn kernels for bioethanol production and
corncobs for natural-gas tanks.
Source: Calculations by Peter Pfeifer, MU
professor of physics,
using data from the Corn
Refiners Association.
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. Carbon monoxide and nitrogen oxides, smog-producing
gases, are reduced by more than 90 percent and 60 percent, respectively.
Carbon dioxide, a greenhouse gas, is reduced by 30 to 40 percent.
- In medium- and heavy-duty applications,
natural gas engines have shown a more than 90 percent reduction
of carbon monoxide and particulate matter and a more than 50
percent reduction of nitrogen oxides, relative to commercial
diesel engines.
Most natural gas used in the U.S. is domestically
produced.
- In 2004, U.S. net imports of natural
gas represented only 15 percent of the total amount used, with
almost all imports coming from Canada.
Source: U.S.
Department of Energy, Energy Efficiency and Renewable Energy,
Alternative Fuel Vehicles
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
Natural gas can be
produced from renewable sources such as landfills.
- As municipal solid waste decomposes,
it produces carbon dioxide and methane. That methane, the principal
component of natural gas, can be captured by landfill gas energy
facilities and combusted for energy.
Source: Energy
Information Administration
- Uncaptured methane is a greenhouse
gas that is more than 20 times more potent than carbon dioxide.
Source: U.S.
Environmental Protection Agency, Landfill Methane Outreach Program
- Capturing methane from all U.S. landfills
is equivalent to removing the annual greenhouse-gas emission
from 50 million cars, or planting forests on an area 2 times
the area of Missouri every year, and could power 4 million homes
or 4 million cars annually ("pollutant to renewable energy").
Sources: U.S. Environmental
Protection Agency, Landfill Methane Outreach Program; Additional
calculations by Peter Pfeifer, MU professor of physics
Natural-gas fueled vehicles are functionally
comparable to conventionally fueled vehicles.
- Horsepower, acceleration and cruise speed
in natural-gas-powered vehicles are comparable to equivalent
conventionally fueled vehicles.
- Approximately 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
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Last Update:
November 19, 2007
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