ME165-1_Week-9.1 Fuel Cells_621865.pdf

8/17/2019 ME165-1_Week-9.1 Fuel Cells_621865.pdf

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ME165-1

ALTERNATIVE ENERGY RESOURCES

EWeek-9.1 Fuel Cells

2015-2016 / 3T


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Fuel Cells

What is a fuel cell?

A fuel cell is a device that converts the chemical energy fro

into electricity through a chemical reaction with oxygen or

oxidizing agent.

Hydrogen is the most common fuel, but hydrocarbons suc

gas and alcohols like methanol are sometimes used. Fuel cells are different from batteries in that they require a

source of fuel and oxygen to run, but they can produce ele

continually for as long as these inputs are supplied.


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Fuel Cells

Fuel Cell Welsh Physicist William Grove developed the first crude fu

1839.

The first commercial use of fuel cells was in NASA space p

generate power for probes, satellites and space capsules. S

fuel cells have been used in many other applications. Fuel cells are used for primary and backup power for com

industrial and residential buildings and in remote or inacce

They are used to power fuel cell vehicles, including automo

buses, forklifts, airplanes, boats, motorcycles and submarine


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Fuel Cells

History of fuel cells

The principle of the fuel cell was discovered by German sci

Christian Friedrich Schönbein in 1838 and published in one

scientific magazines of the time.

Based on this work, the first fuel cell was demonstrated by a

scientist and barrister Sir William Robert Grove in the Febredition of the Philosophical Magazine and Journal of Science

sketched, in 1842, in the same journal.

The fuel cell he made used similar materials to today's phos

fuel cell.


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Fuel Cells

History of fuel cells (cont’d.)

In 1955, W. Thomas Grubb, a chemist working for the GeneCompany (GE), further modified the original fuel cell design

sulphonated polystyrene ion-exchange membrane as the ele

Three years later another GE chemist, Leonard Niedrach, d

way of depositing platinum onto the membrane, which serv

catalyst for the necessary hydrogen oxidation and oxygen r

reactions. This became known as the "Grubb-Niedrach fuel


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Fuel Cells


GE went on to develop this technology with NASA and MAircraft, leading to its use during Project Gemini. This was

commercial use of a fuel cell.

In 1959, British engineer Francis Thomas Bacon successfull

a 5 kW stationary fuel cell.

In 1959, a team led by Harry Ihrig built a 15 kW fuel cell t

Allis-Chalmers, which was demonstrated across the U.S. at

This system used potassium hydroxide as the electrolyte a

compressed hydrogen and oxygen as the reactants.


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Fuel Cells


Later in 1959, Bacon and his colleagues demonstrated a pr

kilowatt unit capable of powering a welding machine.

In the 1960s, Pratt and Whitney licensed Bacon's U.S. paten

in the U.S. space program to supply electricity and drinking

(hydrogen and oxygen being readily available from the spac

tanks).

In 1991, the first hydrogen fuel cell automobile was develo

Roger Billings.


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Fuel Cells


United Technologies Corporation's UTC Power subsidiary

first company to manufacture and commercialize a large, s

fuel cell system for use as a co-generation power plant in

universities and large office buildings.

UTC Power marketed their fuel cell, the PureCell 200, asystem, now replaced by a 400 kW version, the PureCel

400.


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Fuel Cells


UTC Power continues to be the sole supplier of fuel cel

for use in space vehicles, having supplied fuel cells for the

missions, and the Space Shuttle program, and is developi

for automobiles, buses, and cell phone towers.

The company has demonstrated the first fuel cell capable

under freezing conditions with its proton exchange mem


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Fuel Cells

Fuel Cells Design

Fuel cells come in many varieties; however, th

work in the same general manner.

They are made up of three adjacent segments

the anode, the electrolyte, and

the cathode.


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Fuel Cells

Block diagram of a fuel cell


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Fuel Cells

Fuel Cells Design (cont’d.)

Two chemical reactions occur at the interfaces of tdifferent segments.

The net result of the two reactions is that fuel is co

water or carbon dioxide is created, and an electric

created, which can be used to power electrical devnormally referred to as the load.


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Fuel Cells

Fuel Cells Design (cont’d.)

At the anode a catalyst oxidizes the fuel, usually hydrogen,fuel into a positively charged ion and a negatively charged

The electrolyte is a substance specifically designed so ions

through it, but the electrons cannot. The freed electrons tr

through a wire creating the electric current. The ions trave

the electrolyte to the cathode.

Once reaching the cathode, the ions are reunited with the

and the two react with a third chemical, usually oxygen, to

water or carbon dioxide.


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Fuel Cells

Most important design features in a fuel cell

The electrolyte substance. The electrolyte substance usualthe type of fuel cell.

The fuel that is used. The most common fuel is hydrogen.

The anode catalyst, which breaks down the fuel into elect

ions. The anode catalyst is usually made up of very fine pla

powder.

The cathode catalyst, which turns the ions into the waste

like water or carbon dioxide. The cathode catalyst is often

of nickel but it can also be a nanomaterial-based catalyst.


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Fuel Cells

To deliver the desired amount of energy, the fuel cel

combined in series and parallel circuits, where serieshigher voltage, and parallel allows a higher current to

supplied. Such a design is called a fuel cell stack. The

surface area can be increased, to allow stronger curr

each cell.


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Fuel Cells

Types of fuel cells design Proton Exchange Membrane Fuel Ce Solid Oxide Fuel Cell

Alkaline Fuel Cell

Molten Carbonate Fuel Cell

Phosporic Acid Fuel Cell

Direct Methanol Fuel Cell

Electro-galvanic Fuel Cell

Microbial Fuel Cell


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Fuel Cells

Proton Exchange Membrane Fuel Cell


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Fuel Cells

Solid Oxide Fuel Cell

The chemical reactions for the SOFC system can be expr

as follows:

Anode Reaction: 2H2 + 2O2− → 2H2O + 4e−

Cathode Reaction: O2 + 4e – → 2O2−

Overall Cell Reaction: 2H2 + O2→

2H2O Oxygen gas is fed through the cathode, where it reacts w

electrons to create oxygen ions.

The oxygen ions then travel through the electrolyte to re

with hydrogen gas at the anode.


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Fuel Cells

Solid Oxide Fuel Cell (cont’d.)

The reaction at the anode produces electricity and

by-products. Carbon dioxide may also be a by-prod

depending on the fuel, but the carbon emissions fro

SOFC system are less than those from a fossil fuel

combustion plant.


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Fuel Cells

Molten Carbonate Fuel Cell

The chemical reactions for the MCFC system can be exprfollows:

Anode Reaction: CO32− + H2 → H2O + CO2 + 2e−

Cathode Reaction: CO2 + ½O2 + 2e− → CO32−

Overall Cell Reaction: H2 + ½O2→

H2O The hydrogen in the gas reacts with carbonate ions from t

electrolyte to produce water, carbon dioxide, electrons an

amounts of other chemicals.


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Fuel Cells

Molten Carbonate Fuel Cell (cont’d.)

The electrons travel through an external circuit celectricity and return to the cathode.

There, oxygen from the air and carbon dioxide r

from the anode react with the electrons to form

carbonate ions that replenish the electrolyte, comthe circuit.


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Fuel Cells

Fuel cell name Electrolyte Qualified

power (W)

Working

temperature

(°C)

Efficiency

(cell)

Efficiency

(system)

Status Cost (U

Electro-galvanic fuel cell Aqueous alkaline

solution

39 !< 40 Commercial /

Research

Microbial fuel cell Polymer membrane

or humic acid

39 !< 40 Research

Alkaline fuel cell Aqueous alkaline

solution

10000 !10 –

100 kW

79 !< 80 65% !60 –

70%

62% Commercial /

Research

Direct methanol fuel cell Polymer membrane

(ionomer)

0.1 !100

mW – 1 kW

105 !90 – 120 25% !20 –

30%

15% !10 – 20% Commercial /

Research

1

Proton exchange

membrane fuel cell

Polymer membrane

(ionomer)

100 !100 W

– 500 kW

125 !50 – 120

(Nafion)125 – 220 (PBI)

60% !50 –

70%

40% !30 – 50% Commercial /

Research

50 –

Phosphoric acid fuel cell Molten phosphoric

acid (H3PO4)

999999 !<

10 MW

175 !150-200 55% 40% !40%

Co-Gen: 90%

Commercial /

Research

4 –

Molten carbonate fuel cell Molten alkaline

carbonate

100000000

!100 MW

625 !600 – 650 55% 47% Commercial /

Research

Tubular solid oxide fuel

cell (TSOFC)

O2--conducting

ceramic oxide

99999999 !<

100 MW

975 !850 – 1100 63% !60 –

65%

57% !55 – 60% Commercial /

Research

Direct carbon fuel cell Several different 775 !700 – 850 80% 70% Commercial /

Research

Planar Solid oxide fuel cell O2--conductingceramic oxide

99999999 !<100 MW

975 !500 – 1100 63% !60 – 65%

57% !55 – 60% Commercial /Research

Comparizon of Fuel Cell Types


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Fuel Cells

Three Most Common Applications of Fuel

Power

Cogeneration

Fuel cell electric vehicles (FCEVs)


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Applications of Fuel Cells

Power

Stationary fuel cells are used for commercial, indus

residential primary and backup power generation.

Fuel cells are very useful as power sources in remo

locations, such as spacecraft, remote weather statio

parks, communications centers, rural locations incluresearch stations, and in certain military application


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Power (cont’d.)

A fuel cell system running on hydrogen can be comlightweight, and have no major moving parts. Becau

cells have no moving parts and do not involve comb

ideal conditions they can achieve up to 99.9999% re

This equates to less than one minute of downtime year period.


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Cogeneration

Combined heat and power (CHP) fuel cell systemsMicro combined heat and power (MicroCHP) syst

used to generate both electricity and heat for hom

home fuel cell), office building and factories.

The system generates constant electric power (seexcess power back to the grid when it is not consu

and at the same time produces hot air and water f

waste heat. MicroCHP is usually less than 5 kWe fo

fuel cell or small business.


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Cogeneration (cont’d.)

The waste heat from fuel cells can be diverted durisummer directly into the ground providing further

while the waste heat during winter can be pumped

into the building. The University of Minnesota owns

patent rights to this type of system.


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Fuel cell electric vehicles (FCEVs)


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Other Applications

Providing power for base stations or cell sites.

Distributed generation.

Emergency power systems, are a type of fuel cell system, w

include lighting, generators and other apparatus, to provide

resources in a crisis or when regular systems fail. They findwide variety of settings from residential homes to hospital

laboratories, data centers, telecommunication equipment a

modern naval ships.


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Other Applications (cont’d.)

An uninterrupted power supply (UPS) provides empower and, depending on the topology, provide line

regulation as well to connected equipment by supp

power from a separate source when utility power i

available. Unlike a standby generator, it can provide protection from a momentary power interruption.


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Other Applications (cont’d.)

Base load power plants. Fuel cell APU for Refuse Collection Vehicle.

Hybrid vehicles, pairing the fuel cell with either an ICE or

Notebook computers for applications where AC charging

be readily available.

Portable charging docks for small electronics (e.g. a belt cl

charges your cell phone or PDA).

Smartphones, laptops and tablets.

Small heating appliances.


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Textbooks

Renewable Energy Technologies, Jean-Claude Sabonnadiere, 2009 Energy Conversion, D. Yogi Goswami, Frank Kreith, 2008

Power Plant Engineering, 3rd Edition, PK Nag, 2008, Tata McGraw Hi

Web http://en.wikipedia.org/wiki/Fuel_cell

References
http://en.wikipedia.org/wiki/Fuel_cellhttp://en.wikipedia.org/wiki/Fuel_cellhttp://en.wikipedia.org/wiki/Fuel_cell

ME165-1_Week-9.1 Fuel Cells_621865.pdf

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