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Hydrogen can be produced domestically
from fossil fuels (such as coal), nuclear power, or renewable
resources, such as hydropower. Fuel cell vehicles powered by
pure hydrogen emit no harmful air pollutants.
FUEL CELL VEHICLES
What is Hydrogen
Hydrogen is the simplest, lightest and most plentiful element in the
universe. It is made up of one proton and one electron revolving around
the proton. In its normal gaseous state, hydrogen is colourless,
odourless,
tasteless, non-toxic and burns invisibly. It should not be considered a
"fuel," but instead, should be considered as an energy transport
mechanism.
Where does Hydrogen come
from
Currently, most hydrogen is made from natural gas through a process
known as reforming. Reforming separates hydrogen from hydrocarbons by
adding heat. Hydrogen can also be produced from a variety of sources
including water and biomass.
What is a fuel cell
Fuel cells generate electricity from a catalyst-facilitated chemical
reaction between hydrogen and oxygen ions in a cell. Several cells
combined make up a fuel cell stack. Fuel cell systems have relatively
few moving parts, and their only by products are water and heat when
pure hydrogen is used as the fuel.
A fuel cell converts the chemical energy of a fuel directly into
electricity without any intermediate thermal or mechanical processes.
The electrical energy can be used to do useful work directly, while the
heat is either wasted or used for other purposes.
A fuel cell "stack" requires fuel, oxidant and coolant in order to
operate. The gases must be humidified, and the coolant temperature must
be controlled. To achieve this, the fuel cell stack must be surrounded
by a fuel system, fuel delivery system, air system, stack cooling
system, and humidification system.
The Future of Hydrogen Vehicles
Possible hydrogen
vehicles in the future may be
Vehicles with internal combustion engines using pure hydrogen, or
using a mix of hydrogen and natural gas.
Vehicles with fuel cells that use hydrogen that's produced either
on-board by converting liquid fuels (gasoline, ethanol, or methanol) to
hydrogen, or by using direct hydrogen that has been generated off-board
and stored on the vehicle in compressed or liquid form.
Like
electric vehicles, fuel cell vehicles use electricity to power motors
located near the vehicle's wheels. In contrast to electric vehicles,
fuel cell vehicles produce their primary electricity using a fuel cell.
The fuel cell is powered by filling the fuel tank with hydrogen.
The most
common type of fuel cell for vehicle applications is the polymer
electrolyte membrane (PEM) fuel cell. In a PEM fuel cell, an electrolyte
membrane is sandwiched between a positive electrode (cathode) and a
negative electrode (anode). Hydrogen is introduced to the anode and oxygen
to the cathode. The hydrogen molecules travel through the membrane to the
cathode but not before the membrane strips the electrons off the hydrogen
molecules.
The
electrons are forced to travel through an external circuit to recombine
with the hydrogen ions on the cathode side, where the hydrogen ions,
electrons, and oxygen molecules combine to form water. The flow of
electrons through the external circuit forms the electrical current needed
to power a vehicle.
Fuel cell vehicles can be fuelled with pure hydrogen gas stored
directly on the vehicle or extracted from a secondary fuel—such as
methanol, ethanol, or natural gas—that carries hydrogen. These secondary
fuels must first be converted into hydrogen gas by an onboard device
called a reformer. Fuel cell vehicles fuelled with pure hydrogen emit no
pollutants, only water and heat. Vehicles that use secondary fuels and a
reformer produce only small amounts of air pollutants.
Fuel cell vehicles can be equipped with other advanced technologies to
increase efficiency, such as regenerative braking systems, which capture
the energy lost during braking and store it in a large battery.
Fuel Cell Vehicle and
Infrastructure Development
Because fuel cell vehicles require a completely new vehicle propulsion
system and new fuelling infrastructure, many deployment issues can only be
addressed by integrating and evaluating the components in complete
systems. The U.S. Department of Energy (DOE) is developing and testing
complete system solutions that address all elements of infrastructure and
vehicle technology, validating integrated hydrogen and fuel cell
technologies for transportation, infrastructure, and electric generation
in a systems context under real-world operating conditions.
Resources
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DRIVERS
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