Electrolysis of Water

Peter Lindner

Ridgewood High School

December 1, 2010

“Energy can neither be created or destroyed, it can only be changed from one form to another”

– Albert Einstein

Conventional Alternate

How do we store electricity?

• Through ChemistryFossil Fuels

Batteries

Hydrogen

Why is Hydrogen such a big deal?

Energy Density

(Mega Joules per kilogram)

Li-ion Battery 0.54

Gasoline 46.9

Hydrogen 120.0

~ 220 times more energy than batteries

~ 2.6 times more energy than gasoline

NO AVAILABLE SOURCE OF HYDROGEN

Electrolysis of WaterElectrolysis: Using electricity to drive a non-spontaneous chemical reaction

H2 and O2

What do we need?• Water

• Electrolyte (PEM, salt water, citric acid)

• Metal electrodes (Anode +, Cathode -)

• Electricity

Chemical what Happens

• Anode (positive):

• Cathode (negative):

OVERALL:

2H2O O2+4H++4e-

4H++4e-2H2

2H2O O2+2H2

What is a PEM

• PEM – Proton Exchange Membrane• Used as fuel cells to produce electricity

• Must use deionized water• Can be run backwards as an electrolyzer

Proton Exchange Membrane

DEMO

4H++4e-2H22H2O O2+4H++4e-

How do we use the Hydrogen?

• Fuel Cells (electrolyzer in reverse)

• Run on H2 and O2 to form clean water.

• Water can then be recycled to electrolyzer.

What are we going to do?

• Setup PEM electrolyzer(s).

• Produce efficiency curves of PEM using simple circuitry.

• Determine Hydrogen Generation Rate vs. Power input.

Build our own electrolyzer powered by our Solar Cells

Electrolyte

Solar Cell

Design a Power Plant

Electricity!!!

What Industry Wants to Make

Solar Cells

Electrolysis of Water

• http://www.youtube.com/watch?v=VnYSw349qvM

Questions???

Take Away’s

• Solar cells can make electricity• That electricity can be used to produce hydrogen

from water• Hydrogen can be used to store energy• Electricity can then be produced by running

hydrogen through Fuel cells.

PEM – Proton Exchange Membrane

Anode – Positive Electrode

Cathode – Negative Electrode