Hydrogen economy fuel cells - vscht.cz · • hydrogen transportation • hydrogen storage –energy density • infrastructure –centralized production / on site production Hydrogen

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Hydrogen economyfuel cellsMartin Paidar

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Future hydrogen economy

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Hydrogen for energy storage

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• hydrogen – sources, quality, accesibility (transport)• safety + legislation – lack of law, standardization, technical notes• Pt based catalysts – water elz., PEMFC - price• construction materials – high temperature FC, high pressure hydrogen• manufacturing scale up- laboratory scale industrial scale

Obstracles

5www.iea.org

Today hydrogen sources

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Hydrogen storage and transportation

• liquid (cryogenic) hydrogen - high energy density- loss during storage- expensive production

• pressurized hydrogen- 700 bar- 300 bar

• hydrogen rich compounds- NH3, NaBH4, ...

• long distance transportation – more

energy for transportation than carried

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Safety + legislation

• increased requirements – mobile applications• risk of well-known accident – loss of public support• slow legislation – problematic introduction to the market

Hindenburg 1937

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Advantages: no emisionshigh energy density

Disadvantages: pricelifetime

high efficiencyflexibilita

sources of fuel (fossil fuel)

inventors:

1839 William Grove1959 Francis Bacon (5 kW)

Fuel cell

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Characteristic AFC PEMFC PAFC MCFC SOFC Temperature 60 – 90 °C 50 – 90 °C 160 – 220 °C 620 – 660 °C 800 – 1000 °C Fuel pure

hydrogen pure hydrogen, reformate *

pure hydrogen, reformate

natural gas, reformed or directly fed, biogas, coal gas

natural gas, reformed or directly fed, biogas, coal gas

Oxidant pure oxygen pure oxygen or air air air air Application space and

military space, military, automotive, and stationary

cogeneration power plant

cogeneration or combined cycle power plants, depending on size

System power at present

50 kW – 250 kW 11 MW 2 MW demonstration plant 100 kW demonstration plant

Electrical efficiency

Stack 69 – 70 % 50 – 68 % 55 % 65 % 60 – 65 %

System 62 % 43 – 58 % 40 % 54 % (cogeneration) 60 – 65 % (combined cycle)

> 50 % (cogeneration) 65 – 70 % (combined cycle)

2000, Ullmann's Encyclopedia of Industrial Chemistry

Fuel cell types

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Fuel cell types

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Stack

• single cell low voltage below Uteor = 1,2 V (currentless conditions)

• for practical applications – connection to series necessary - stack (up to 100s of cell)

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most frequently studied type of FC electrolyte – proton conductive membrane carbon based porous gas diffusion electrodes with Pt catalyst operating temperature 0 - 100ºC (best performance 70-90 ºC) efficiency up to 85% (in case of cogeneration), electric efficiency 37 – 50%. highest volumetric performance (performance/mass ratio) flexible – fast response on load changes sensitive towards CO poisoning – high purity hydrogen required

FC with proton conductive membrane (PEMFC)

www.h-tec.comNedStack PM25-125

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Principle

construction

anode 4e4H2H2 E0 = 0 V

cathodeO2HO4e4H 22 E0 = 1,23 V

Membrane

Electrodes

„solid electrolyte“permeable for H+

perfluorinated polymer (NafionR )

GDE (gas diffusion electrodes)

PEMFC

CF2 CF CF2

CF2 CFOCF3O

CF2 CF2 SO3Hn

x

Nafion

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electrolyte - (ZrO2) doped Y catalyst - Ni/ZrO2 cermets operating temperature 700 - 1000 ºC (600 oC) efficiency - electric 50-60%, in case of cogeneration 80-90% “internal” reformate production – hydrocarbons as fuel e.g. CH4

construction materials – high temperature stability requirements resistive to CO and CO2

FC with solid oxides electrolyte (SOFC)ZrO2 + 8 až 10 % mol. Y2O3

Solid Oxide Fuel Cell Designs at the Cathode

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Output voltage of FC is below theoretically calculated value flowing from Gibbs energy:

-activation owerpotential

-electrolyte fuel penetration (cross-over)

-electrolyte conductivity

-ohmic loss

-mass transport in the electrodes

Fuel cell potential

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fuel/oxidant (gas)

ionic conductor

electric conductor

Nafion

e-

H2

H+

carbon Pt

Three phase contact 4e4H2H2

O2HO4e4H 22

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• FC sensitivity towards catalyst poisons CO, S• natural gas – midterm perspective• hydrogen transportation• hydrogen storage – energy density • infrastructure – centralized production / on site production

Hydrogen for FC

Source of hydrogen produced in 2003 IEA

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• military / space programs • mobile application – transportation (motorbikes - tankers and planes)• stationary units - big up to MW

- small 1 kW• small portable units – alternative to batteries

Fuel cell applications

0

2500

5000

7500

1930 1950 1970 1990 2010

rok

poče

t pat

entů

zdroj: SciFinder, American Chemical Society

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• minimum emissions• silent operation

Mobile applications

Honda FCX Clarity• demonstrated – cars, trains, airplanes, boats,..• main target – car industry• Honda FCX Clarity – 1st commercially available car

http://www.netinform.net/H2/H2Stations/

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• big SOFC installations in future – high el. efficiency• today middle-size units MCFC, SOFC, (PAFC) around 200 kW

connected to get desired performance• reached el. performance 60%

Siemens-Westinghouse 36000 h of operation, 0.1% drop of el. efficiency/1000h

• target 800 US$ /kW

Stationary units

1,4 MW installation of PAFC by UTC Power, Garden City USA

Ullmann's Encyclopedia of Industrial Chemistry

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• today most perspective course (30% year increase predicted)power back-up for e.g. telecommunications – better lifetime than batteries

μ-cogeneration residential houses power source 5 kW (USA), 1-2 kW (EU)• mainly PEMFC and SOFC• el. efficiency up to 50%, overall up to 90%• fuel – H2 or natural gas• lifetime > 40 000 h• government support - Japan ~ 1000 units• target 6000 US$ / unit 2012

Small stationary units

Astris AFC unit E6 1.8 kW Plug Power - Fuel Cell Systems for Telecom Backup Power

EBARA Ballard 1kW Japan Cogeneration System

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• simplicity + easy maintenance - DMFC• price + performance not main point – yachts, satelite phones atc.• main advantage independent on electric grid, refueling, silent operation

handheld products • battery replacement – no recharge• PEMFC or DMFC• low operating conditions – low performance• „breathing“ cells • fuel distribution ?

Portable power sources

The HydroPak fuel-cell power supply

MTI micro Mobion® direct methanol fuel cell (DMFC)

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Future hydrogen economy – longtime process