Datasheet

5 6
e-
Fuel H (Hydrogen)
2
2
Used Fuel Recirculates
Flow Field Plate
Gas Diffusion Electrode (Anode)
Catalyst
O (Oxygen)
Heat
Air + Water Vapor
Flow Field Plate
Gas Diffusion Electrode (Cathode)
Catalyst
Electric Circuit
Proton Exchange Membrane
e
e
e
e
e
e
e
e
O
O
O
2H
2
2
O2
H2
magnified
H2O
PEM reversible fuel cell
(fuel cell function)
side view
PEM reversible
fuel cell
B. Electrolyzer function of the reversible fuel cell: how does it work?
Electrolysis is the use of electrical energy to produce a chemical change. In the renewable hydro-
gen cycle, electrical energy (from renewable resources) is used to break the bonds between the
hydrogen and oxygen in the water, releasing them as elemental gases. Hydrogen is “stored“ renew-
able energy.
An electrolyzer is a device that facilitates the electrolysis of water to produce hydrogen gas. Electrolyz-
ers most commonly used today generate hydrogen at relatively low pressures (from nearly atmo-
spheric pressure up to 200 pounds per square inch) and use a liquid alkaline electrolyte (KOH or
NaOH). At these pressures, storage of large quantities of hydrogen requires extremely large storage
vessels. One solution to this problem is to use a compressor to increase the hydrogen pressure.
However, the energy investment required to pressurize hydrogen, as well as the maintenance
of hydrogen compressors, makes this option difficult for a large-scale application of this technol-
ogy. Furthermore, the operation of alkaline electrolyzers requires frequent maintenance that includes
disposal and replacement of the highly caustic electrolyte.
New approaches to water electrolysis include proton exchange membrane electrolyzers, which is the
electrolysis function of the reversible fuel cell in this kit. Such an electrolyzer can be designed to elec-
trochemically generate hydrogen at pressures of 2000 psi or greater, thus eliminating the need for
mechanical compression. No caustic alkaline or acidic fluid electrolyte is required. Additional ad-
vantages of PEM electrolysis over alkaline electrolysis include lower parasitic energy losses and
higher purity hydrogen output. PEM electrolysis is potentially a simple, sustainable, and cost-
effective technology for generating, compressing, and storing hydrogen.