Hydrogen Economy

When the Sun’s radiation reaches the Earth, some radiation is reflected and some is absorbed by the Earth’s surface or the atmosphere. The energy is then radiated back into space. However, some of the infrared light from the Earth is absorbed by the atmosphere and then re-emitted back to the Earth’s surface. This makes the Earth’s surface temperature greater than it should be for the amount of radiation that it is receiving from the Sun. This phenomenon is known as the greenhouse effect [1].

The atmosphere absorbs infrared light that corresponds to the energies of the vibrations of various molecules in the atmosphere. Some of the molecules that contribute to the greenhouse effect are water, carbon dioxide, methane, nitrous oxide and chlorofluorocarbons. Anthropogenic emissions of carbon dioxide, methane, nitrous oxide, and chlorofluorocarbons are cause for concern because more greenhouse molecules in the atmosphere will cause more infrared absorption. This means more heat will be reradiated back to the Earth's surface, which will increase the temperature even more. This phenomenon is called global warming. Global warming could cause problems such as melting glaciers and expanding the water in the ocean, which would raise sea level. It could change weather patterns and cause more hurricanes [2]. Carbon dioxide is one of the biggest contributers to the greenhouse effect, and since it is a product of the combustion of fossil fuels, one incentive for moving to a hydrogen economy is that this would ameliorate the effects of global warming.

This graph shows the world's temperature increase over time.

Another problem with global warming is that it could increase the size of the polar ozone holes. If more heat is absorbed by molecules in the troposphere and reradiated back to the Earth's surface, then less heat will reach the stratosphere. As a result, it will become colder. If the stratosphere becomes colder, then the polar ice clouds that contribute to the ozone holes will last longer, and the ozone will be depleted even more than it is currently.

Effects of a Hydrogen Economy

Carbon dioxide has been receiving a lot of attention regarding its contribution to global warming, so a fuel source that reduces the amount of carbon dioxide emissions looks attractive. A hydrogen economy would ideally not produce carbon dioxide. However, carbon dioxide may or may not actually be produced depending on how hydrogen is made. If the processes used to produce hydrogen require outside energy, and fossil fuels are used for that energy, then there will still be high CO2 emissions. However, if hydrogen is produced from a process such as electrolysis of water powered by solar energy, then there will be a lower emission of CO2. This would help reduce the greenhouse effect and global warming.

Even if the carbon dioxide emissions decrease, there could be other factors that would worsen the greenhouse effect. If there are high leaks of hydrogen, then there will more H2 released to the atmosphere, and the amount of hydroxyl radicals will decrease. This will increase the atmospheric lifetime of methane and NO2, among other gases. Since methane is a greenhouse gas, a longer lifetime will mean an increase in radiative forcing [3]. It is estimated that for every mole of hydrogen gas released, there will be around 0.01 moles extra methane in the atmosphere [3]. Therefore, hydrogen gas would contribute indirectly to the greenhouse effect and global warming.

As with the other effects of hydrogen in the atmosphere, the effect of hydrogen on global warming depends greatly on how hydrogen is produced, and the extent of hydrogen gas leaking to the atmosphere [4]. It is conceivable that if hydrogen is produced using fossil fuel energy and if there are large hydrogen leaks, then a hydrogen economy would actually worsen global warming. However, if renewable energy sources are used to produce hydrogen and there are small hydrogen leaks, then global warming could be reduced.

1. Spiro, T.G. and W.M. Stigliani, Chemistry of the Environment. Second ed. 2003, Upper Saddle River, NJ: Prentice Hall.

2. Seinfeld, J.H. and S.N. Pandis, Atmospheric Chemistry and Physics: From Air Pollution to Climate Change. 1998, New York: John Wiley & Sons, Inc.

3. Prather, M.J., An environmental experiment with H₂. Science, 2003. 302: p. 581-582.

4. Schultz, M.G., et al., Air pollution and climate-forcing impacts of a global hydrogen economy. Science, 2003. 302: p. 624-627.

Introduction

Production

Storage & Infrastructure

Atmospheric Effects

Government Involvement

Conclusions



Introduction Production Storage & Infrastructure Applications Atmospheric Effects Hydrogen in the Atmosphere Today NO_x Greenhouse Effect Ozone Destruction Government Involvement Conclusions	Greenhouse Effect What is the Greenhouse Effect? When the Sun’s radiation reaches the Earth, some radiation is reflected and some is absorbed by the Earth’s surface or the atmosphere. The energy is then radiated back into space. However, some of the infrared light from the Earth is absorbed by the atmosphere and then re-emitted back to the Earth’s surface. This makes the Earth’s surface temperature greater than it should be for the amount of radiation that it is receiving from the Sun. This phenomenon is known as the greenhouse effect [1]. The atmosphere absorbs infrared light that corresponds to the energies of the vibrations of various molecules in the atmosphere. Some of the molecules that contribute to the greenhouse effect are water, carbon dioxide, methane, nitrous oxide and chlorofluorocarbons. Anthropogenic emissions of carbon dioxide, methane, nitrous oxide, and chlorofluorocarbons are cause for concern because more greenhouse molecules in the atmosphere will cause more infrared absorption. This means more heat will be reradiated back to the Earth's surface, which will increase the temperature even more. This phenomenon is called global warming. Global warming could cause problems such as melting glaciers and expanding the water in the ocean, which would raise sea level. It could change weather patterns and cause more hurricanes [2]. Carbon dioxide is one of the biggest contributers to the greenhouse effect, and since it is a product of the combustion of fossil fuels, one incentive for moving to a hydrogen economy is that this would ameliorate the effects of global warming. This graph shows the world's temperature increase over time. Another problem with global warming is that it could increase the size of the polar ozone holes. If more heat is absorbed by molecules in the troposphere and reradiated back to the Earth's surface, then less heat will reach the stratosphere. As a result, it will become colder. If the stratosphere becomes colder, then the polar ice clouds that contribute to the ozone holes will last longer, and the ozone will be depleted even more than it is currently. Effects of a Hydrogen Economy Carbon dioxide has been receiving a lot of attention regarding its contribution to global warming, so a fuel source that reduces the amount of carbon dioxide emissions looks attractive. A hydrogen economy would ideally not produce carbon dioxide. However, carbon dioxide may or may not actually be produced depending on how hydrogen is made. If the processes used to produce hydrogen require outside energy, and fossil fuels are used for that energy, then there will still be high CO2 emissions. However, if hydrogen is produced from a process such as electrolysis of water powered by solar energy, then there will be a lower emission of CO2. This would help reduce the greenhouse effect and global warming. Temperature changes if the CO2 level in the atmosphere doubles and quadruples. Even if the carbon dioxide emissions decrease, there could be other factors that would worsen the greenhouse effect. If there are high leaks of hydrogen, then there will more H2 released to the atmosphere, and the amount of hydroxyl radicals will decrease. This will increase the atmospheric lifetime of methane and NO2, among other gases. Since methane is a greenhouse gas, a longer lifetime will mean an increase in radiative forcing [3]. It is estimated that for every mole of hydrogen gas released, there will be around 0.01 moles extra methane in the atmosphere [3]. Therefore, hydrogen gas would contribute indirectly to the greenhouse effect and global warming. As with the other effects of hydrogen in the atmosphere, the effect of hydrogen on global warming depends greatly on how hydrogen is produced, and the extent of hydrogen gas leaking to the atmosphere [4]. It is conceivable that if hydrogen is produced using fossil fuel energy and if there are large hydrogen leaks, then a hydrogen economy would actually worsen global warming. However, if renewable energy sources are used to produce hydrogen and there are small hydrogen leaks, then global warming could be reduced. Sources: 1. Spiro, T.G. and W.M. Stigliani, Chemistry of the Environment. Second ed. 2003, Upper Saddle River, NJ: Prentice Hall. 2. Seinfeld, J.H. and S.N. Pandis, Atmospheric Chemistry and Physics: From Air Pollution to Climate Change. 1998, New York: John Wiley & Sons, Inc. 3. Prather, M.J., An environmental experiment with H₂. Science, 2003. 302: p. 581-582. 4. Schultz, M.G., et al., Air pollution and climate-forcing impacts of a global hydrogen economy. Science, 2003. 302: p. 624-627.
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