CHEMISTRY 1

90 USES AND APPLICATIONS

Hydrogen

S ome people consider hydrogen the energy source of the future and predict that in the short term it will gain widespread use in place of fossil

fuels. The hydrogen is combined with oxygen to release energy to generate electricity. Among the advantages of hydrogen-based energy are its very low pollution level (the byproduct of the reaction is water vapor) and its inexhaustibility (it can be recycled and reused). Disadvantages include the complications inherent in handling pure hydrogen, its costs, and

the wide-scale conversion that would be necessary for petroleum-fueled engines and systems.

Fuel Cells

produce electricity from the energy released during the chemical reaction of

hydrogen and oxygen. The engine converts the electrical energy into mechanical energy.

Fuel-cell pack

Flow plate

Hydrogen and oxygen circulate through the channels of their respective plates on either side of the electrolytic membrane.

Cooling cell

The cooling cell should be refrigerated because the reaction produced in the cell generates heat.

0.7 volt

is the voltage generated by a single fuel cell. This energy can scarcely light one lightbulb, but tens or hundreds of cells can be joined together to increase this voltage.

Catalyst

Anode	Catalyst
The electrode in	causes the hydrogen
contact with	nuclei to separate
hydrogen atoms.	from their electrons.

200

is the average number of hydrogen cells a car engine needs.

Separator

Flow plate

Cathode

is the electrode in contact with the oxygen atoms and the place where water vapor forms.

Electrolyte

is a cell through which the hydrogen nuclei pass before reaching the cathode. It does not allow electrons, which flow through the external circuit (electricity), to pass.

The Cleanest Car

The latest hydrogen-fueled models can travel up to 100 miles per hour (160 km/h) and have a range

between 170 and 250 miles (270 and 400 km), depending on whether liquid or compressed hydrogen is used.

Converter	Air
From direct	compressor
current to
alternating current

Air filter

Radiator

cools down the cells.

Fuel cells	Electric engine
use hydrogen and oxygen	causes the car
to generate electricity.	wheels to move.

Hydrogen canister valve

Fuel pipes

carry hydrogen from the tank to the cells.

How a Fuel Cell Works

The fuel cell produces electricity from the energy released when oxygen and hydrogen join to form water.

ENERGY AND MOVEMENT 91

Starter battery

Tank

is designed to store compressed or liquid hydrogen.

Glass fiber

	Exhaust pipe
	releases the water vapor	Carbon
		fiber
	Aluminum
	produced by the process.

Anode

Catalyst

Electrolyte

Catalyst

Cathode

1	Hydrogen collects at the anode and	2	Hydrogen nuclei	3	Electrons, which cannot cross the	4	The byproducts of the
	oxygen at the cathode. The catalyst		cross the electrolytic		electrolytic layer, flow through the		process are water and heat.
	separates the hydrogen electrons		layer without their		circuit until they reach the cathode,		The reaction continues as
	from their nuclei.		electrons.		thereby producing electric current.		long as fuel is supplied.