A Hydrogen Economy - Islamic University of...

transcript

A Hydrogen Economy

Dr. Mazen AbualtayefEnvironmental Engineering Department

Islamic University of Gaza, Palestine

Adapted from a presentation by Professor S.R. Lawrence, Leeds School of Business,

Environmental Studies, University of Colorado, Boulder, CO, USA

Agenda

• A Hydrogen Vision of the Future

• Hydrogen Systems

• Producing Hydrogen

• Storing and Transporting Hydrogen

• Hydrogen Fueled Transport

• Problems with Hydrogen

• The Promise of Hydrogen

• Hydrogen Summary

The Hydrogen H2 Molecule

http://planetforlife.com/h2/index.html

Hydrogen Economy Schematic

Hydrogen Economy in Hong Kong

http://www.gii.com.hk/eng/clean_energy.htm

Hydrogen Fueling Station

Hydrogen Systems

Hydrogen Energy Cycle

http://en.wikipedia.org/wiki/Hydrogen_economy

Hydrogen Production Cycle

Crabtree et al., “The Hydrogen Economy,” Physics Today, Dec 2004

Operating the Hydrogen Economy

Bossel et al., The Future of the Hydrogen Economy: Bright or Bleak?, Oct 28, 2004

http://www.oilcrash.com/articles/h2_eco.htm

Hydrogen Economy Supply Chain

Hydrogen Pathways

http://www.ch2bc.org/index2.htm

Advantages of a Hydrogen Economy

• Waste product of burning H2 is water

• Elimination of fossil fuel pollution

• Elimination of greenhouse gases

• Elimination of economic dependence

• Distributed production

http://www.howstuffworks.com/hydrogen-economy.htm

Issues with Hydrogen

• Not widely available on planet earth

• Usually chemically combined in water

or fossil fuels (must be separated)

• Fossil fuel sources contribute to

pollution and greenhouse gases

• Electrolysis requires prodigious

amounts of energy

Technological Questions

• Where does hydrogen come from?

• How is it transported?

• How is it distributed?

• How is it stored?

Producing Hydrogen

Current Hydrogen Production

•Current hydrogen

production

•48% natural gas

•30% oil

•18% coal

• 4% electrolysis

•Global Production

•50 million tonnes / yr

•Growing 10% / yr

•US Production

•11 million tonnes / yr

Natural Gas

Electrolysis

How is Hydrogen Produced?

• Reforming fossil fuels

• Heat hydrocarbons with steam

• Produce H2 and CO

• Electrolysis of water

• Use electricity to split water into O2 and H2

• High Temperature Electrolysis

• Experimental

• Biological processes

• Very common in nature

• Experimental in laboratories

Steam Reforming

• From any hydrocarbon

• Natural gas typically used

• Water (steam) and hydrocarbon mixed at high temperature (700–1100 °C)

• Steam (H2O) reacts with methane (CH4)

• CH4 + H2O → CO + 3 H2 - 191.7 kJ/mol

• The thermodynamic efficiency comparable to (or worse than) an internal combustion engine

• Difficult to motivate investment in technology

Carbon Monoxide Reforming

• Additional hydrogen can be recovered

using carbon monoxide (CO)

• low-temp (130°C) water gas shift reaction

• CO + H2O → CO2 + H2 + 40.4 kJ/mol

• Oxygen (O) atom stripped from steam

• Oxidizes the carbon (C)

• Liberates hydrogen bound to C and O2

Hydrogen Steam Reforming Plants

Electrolysis of Water (H2O)

http://www.gm.com/company/gmability/edu_k-12/9-12/fc_energy/make_your_own_hydrogen_results.html

Electrolysis of Water

http://hyperphysics.phy-astr.gsu.edu/hbase/thermo/electrol.html

Renewable Energy for Electrolysis

http://www.howstuffworks.com/hydrogen-economy4.htm

Biomass Electrolysis Module

http://www.nrel.gov/hydrogen/photos.html

High Temperature Electrolysis

• Electrolysis at high temperatures

• Use less energy to split water

Biological H2 Creation

•Nature has very

simple methods to

split water

•Scientists are

working to mimic

these processes in the

lab; then commercially

Crabtree et al., “The Hydrogen Economy,” Physics Today, Dec 2004

Storing & Transporting Hydrogen

Hydrogen Storage

• Storage a major difficulty with hydrogen

• H2 has low energy density per volume

• Requires large tanks to store

• H2 can be compressed to reduce volume

• Requires heavy, strong tanks

• H2 can be liquefied to reduce volume

• Both compression and liquefaction require a lot of energy

Ammonia Storage

• H2 can be stored as ammonia (NH3)

• Exceptionally high hydrogen densities

• Ammonia very common chemical

• Large infrastructure already exists

• Easily reformed to produce hydrogen

• No harmful waste

• BUT

• Ammonia production is energy intensive

• Ammonia is a toxic gas

Metal Hydride Storage

• Metal hydrides can carry hydrogen

• Boron, lithium, sodium

• Good energy density, but worse than gas

• Volumes much larger than gasoline

• Three times more volume

• Four times heavier

• Hydrides can react violently with water

• Leading contenders

• Sodium Borohydride

• Lithium Aluminum Hydride

• Ammonia Borane

Transporting Hydrogen

Hydrogen Fueled Transport

Hydrogen-Powered Autos

http://planetforlife.com/h2/h2vehicle.html

Hydrogen-Powered Trucks

Hydrogen-Powered Aircraft

http://aix.meng.auth.gr/lhtee/projects/cryoplane/

Hydrogen powered passenger aircraft with cryogenic tanks

along spine of fuselage. Hydrogen fuel requires about 4 times

the volume of standard jet fuel (kerosene).

Hydrogen-Powered Rockets

Implications of Hydrogen Transport

Weight of fuel

Weight of steel tank

Weight of carbon fiber tank

Volume of tank contents

Volume of tank

Typical 18 wheel truck (diesel)

1175 lb (small) NA 22.5 feet3 24.0 feet3

Typical sedan (gasoline)

108 lb (small) NA 2.25 feet3 2.5 feet3

Truck converted to ICE hydrogen

313 lb 31,300 lb 6,960 lb 67.5 feet3 157 feet3

Sedan converted to hydrogen fuel cell

17.4 lb 1740 lb 387 lb 4 feet3 9 feet3

http://planetforlife.com/h2/h2swiss.html

Problems with Hydrogen

Environmental Concerns

• 48% of hydrogen made from natural gas

• Creates CO2 – a greenhouse gas

• Hydrogen H2 inevitably leaks from

containers

• Creates free radicals (H) in stratosphere

due to ultraviolet radiation

• Could act as catalysts for ozone depletion

Hydrogen vs. Methane

Units Hydrogen Methane

Density kg/m3 0.0887 0.707

Gravimetric Energy MJ/kg 142.0 55.6

Volumetric Energy MJ/m3 12.7 40.0

Hydrogen Energy Losses

• Windmills generate electricity.

• Electricity converted to H2 – 70% efficiency.

• H2 compressed for pumping – 20% energy loss

• H2 pumped long distance – 30% loss

• 65% loss to Europe from the Sahara).

• Loss at filling stations – assume 5%

• Loss in fuel cell – 50% (possibly only 40%)

• Combining losses → only 15-18% useful

electricity, or vehicle motor power

• 9.3% in the case of the Sahara

Criticism of Hydrogen Economy

• Hydrogen economy idea does not work for multiple reasons. • No practical source of cheap hydrogen

• No good way to store hydrogen

• No good way to distribute hydrogen

• Problems with physical & chemical properties of hydrogen• Technology cannot change these facts.

• Compact / convenient future energy carrier needed• Methane, ethane, methanol, ethanol, butane, octane,

ammonia, etc. are better energy carriers.

• Difficult to understand the enthusiasm for hydrogen • Hydrogen does not solve the energy problem and it is a bad

choice for carrying energy.

The Promise of Hydrogen

UNIDO-ICHET Projection

http://www.unido-ichet.org/ICHET-transition.php

UNITED NATIONS INDUSTRIAL DEVELOPMENT ORGANIZATION

INTERNATIONAL CENTRE FOR HYDROGEN ENERGY TECHNOLOGIES

The Iceland Example

• Iceland committed to be the first hydrogen economy

• 2050 goal

• Will use geothermal resources to create hydrogen

• Power autos, buses, and fishing fleet with hydrogen

Hydrogen Summary

Advantages of a Hydrogen Economy

• Waste product of burning H2 is water

• Elimination of fossil fuel pollution

• Elimination of greenhouse gases

• Elimination of economic dependence

• Distributed production

• The stuff of stars

Disadvantages of Hydrogen

• Low energy densities

• Difficulty in handling, storage, transport

• Requires an entirely new infrastructure

• Creates CO2 if made from fossil fuels

• Low net energy yields

• Much energy needed to create hydrogen

A Hydrogen Economy - Islamic University of...

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