Fuel_Cells by nuhman10


									           Ethanol as a Renewable Fuel Source for Fuel Cells
For years, fuel cell technology has offered significant promise as an alternative power source to
increase energy efficiency, reduce pollution, and minimize our dependence on imported oil. Fuel
cell systems have the potential to power automobiles, buses, homes, small generat ors, and
perhaps someday, even computers. Fuel cell vehicles have twice the energy efficiency of internal
combustion engines and are capable of achieving up to 80 mpg, with near zero emis sions.
However, one challenge has historically stood bet ween fuel cell vehicle technology and its
successful commercialization - the storage and supply of hydrogen.

The widespread introduction and use of fuel cell vehicles could have a major impact on improving
air quality in urban areas and reducing pet roleum consumption. Fuel cell vehicles are driven in
large part by environmental regulations requiring "zero" or near -zero emission vehicles in a
growing number of regions across the country. Rising concerns with the contribution of fossil fuels
to global warming provide added impet us to the search for alt ernatives to petroleum and the
internal combustion engine.

These public policy issues are addressed with renewable fuels such as ethanol. In spark ignitio n
engines, ethanol emits significantly less carbon monoxide and air toxic pollution than gasoline,
and therefore reduces the amount of harmful emissions released into the atmosphere. When
coupled with the efficiency of a fuel cell, the air quality benefits will be substantially greater. As a
renewable fuel, ethanol reduces greenhouse gas emissions by closing the carbon cycle. Fossil
fuels release carbon dioxide (CO2) during combustion. But ethanol is produced from agricultural
crops that absorb CO2. Therefore, ethanol's carbon cycle maintains the balance of CO2 in the
atmosphere. In addition, the production and us e of ethanol offers significant rural ec onomic
development opportunities and national and energy security benefits from the domestic
production of energy.

How a Fuel Cell Works: Fuel cells work by combining hydrogen and oxygen in a chemical
reaction to create electricity, without the noise and pollution of conventional engines. In principle,
a fuel cell operates like a battery. Unlike a battery, how ever, a fuel cell does not run down or
require recharging. It will produce energy in the form of electricity and heat as long as fuel is
supplied. Since the fuel cell relies on chemistry and not combustion, emissions are much lower
than from the most efficient internal combustion engines, and consist primarily of water and

Storage of hydrogen on board vehicles has been actively researc hed, but there have been no
breakthroughs, and concerns regarding the safety of hydrogen storage persist. The cost and
feasibility of developing a hydrogen refueling infrastructure also remains a challenge. But there is
a method of reforming hydrogen from various liquid fuels while on board a vehicle. That method is
an on-board multi-fuel cell proc essor, and it has been demonstrated to reform ethanol with higher
efficiencies and lower emissions than gasoline.

Ethanol as a Fuel Source
Ethanol overcomes both the storage and infrastructure challenges of hydrogen. Fuel cells require
a source of hydrogen to produce electricity. Fuel reforming - which uses an electro-chemical
process to extract hydrogen from fuel - offers a practical solution to that challenge. As ethanol is
far easier to store on a vehicle than hy drogen, it offers a practical and exciting alternative to direc t
hydrogen fueling. Ethanol is also much easier to distribute than hydrogen and is already widely
used in the nation's gasoline distribution system. In addition, ethanol is easier to reform than
gasoline and most alternative fuels becaus e of its relatively simple molecular structure.

Fuel infrastructure has been identified by the automobile manufacturers as one of the most critical
issues in determining the choice of fuel for fuel cell powered vehicles because it presents the
most expensive component of the program. Other than gasoline, ethanol presents several
advantages over other fuel sources for fuel cells because the infrastructure is already in place.
Ethanol is currently used in every state in the nation as an octane enhancer or oxygen ate
blended with gas oline. As such, ethanol's infrastructure to the terminal level is complete and the
gasoline industry has experience handling and blending ethanol. To establish the infrastructure at
the terminal level for other fuels that currently exis ts would require a tremendous capital

Ethanol can easily be transport ed from terminal locations to gasoline service stations via truck. At
the servic e station, ethanol can be dispens ed in the same manner as gasoline, with very minor
modifications to the dispensing equipment. In many cases, existing tanks could be used for
ethanol, which may not be the case wit h other alternative fuels. Since ethanol is already
distributed from existing terminals, materials (seals, valves, etc.) utilized are al ready compatible
with ethanol.

                     Benefits of Ethanol as a Renewable Fuel Source

                                 High energy density liquid stores well on

                                 Reductions in greenhouse gas emissions

                                 Delivered through the existing fuel

                                 Can be blended with gasoline for seamless
                                  motor fuel transition

                                 Less toxic than methanol and gasoline and
                                  does not pose as severe a threat to the
                                  environment in the event of a spill

                                 Easier to reform than gasoline,
                                  hydrocarbons and most alternative fuel

                                 Utilizes agricultural, waste and biomass
                                  feedstocks, creating new mark ets for
                                  agricultural products while cont ributing to
                                  rural economic development

                                 Reduced reliance on import ed fossil fuel

Today there are more than 55 domestic fuel ethanol production facilities located in 22 states
across the country with annual capacity of approximately 1.8 billion gallons. More than 400 million
gallons in announced new production facilities are expected to be on -line within the next 24 - 30
months. Furthermore, as ethanol production facilities are largely modular, should certain demand
for ethanol arise, expansions could be done quickly by simply adding new equipment to existing
production facilities. Expansions to existing facilities could easily add 600 million gal lons of
production capacity within the next 12-18 mont hs. In sum, a total of 2.8 billion gallons of
production could be available in the near term. Furthermore, the U.S. Department of Agriculture
has suggested that grain-based ethanol production could grow to as high as 3.3 billion gallons a
year by 2004.
In addition, the next generation of ethanol production facilities will include production from
cellulose and biomass feedstocks. Earlier this year, there was a groundbreaking for a new
ethanol production plant in Jennings, Louisiana which, when completed, will produce et hanol from
rice hulls and bagasse. Three other plants are currently planned in California that will produce
ethanol from rice straw. Already, ethanol is being produced from wood waste by Georgia Pacific
in Washington state, and production from forest residue is not far behind. Conservative estimates
from Oakridge National Laborat ory predict ethanol production from cellulose and biomass
feedstocks to be 3 to 4 billion gallons a year by 2010, which is in addition to grain-based et hanol
production. The estimate grows to 8 billion gallons a year from cellulose feedstocks alone by
2020. That equates to powering at least 10 million fuel cell vehicles with ethanol by 2010, and 20
million vehicles by 2020. Best case scenarios project substantially higher numbers.

A Promi sing Option for Ethanol
Epyx Corporation (a subsidiary of Arthur D. Little) of Cambridge, Massachusetts, has developed a
multi-fuel processor that is capable of converting both renewable fuels (such as ethanol) and
hydrocarbon fuels (such as gasoline) into hydrogen to power various fuel cell applications. The
by-products of this process are water vapor, heat, and 50% less carbon dioxide.

The Epyx multi-fuel cell processor, when combined with a PEM (proton exchange membrane)
fuel cell, can be packaged in a passenger car or bus to create a low-emission, high-efficiency fuel
cell vehicle operating on ethanol. Ethanol provides higher efficiencies, fewer emissions and better
performance than other fuel sources, including gasoline, in the Epyx fuel processor. To date,
methanol fuel reformers have been designed exclusively to process methan ol and cannot utilize
other fuels, such as ethanol or gasoline.

The transportation market for fuel cell power focuses on automotive applications (50 kilowatts)
and urban buses (250 kilowatts). The Chicago Transit Authority (CTA) has plans to use the Epyx
multi-fuel processor for an ethanol fuel cell bus program, beginning soon after the completion of
the CTA's current hydrogen fuel cell bus program in March 2000.

Sources: U.S. Department of Energy, Oak ridge National Labo ratory, Epyx Corporation, Fuel Cells
2000, Renewable Fuels Association, U.S. Department of Agriculture

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