Lesson Objectives

• Describe the major ways that energy use can be reduced.
• Discuss new technologies that are being developed to reduce air pollutants, including greenhouse gases.
• Describe the difference between placing caps on emissions and reducing emissions.

Vocabulary

• biofuel
• cap-and-trade
• carbon sequestration
• carbon tax
• catalyst
• catalytic converter
• fuel cell
• gasification
• hybrid vehicle

Introduction

The Clean Air Act of 1970 and the amendments since then have done a great job in requiring people to clean up the air over the United States. Emissions of the six major pollutants regulated by the Clean Air Act, carbon monoxide, lead, nitrous oxides, ozone, sulfur dioxide, and particulates, have decreased by more than 50%. Cars, power plants, and factories individually release less pollution than they did in the mid-20th century. But there are many more cars, power plants, and factories. Many pollutants are still being released and some substances have been found to be pollutants that were not known to be pollutants in the past. There is still much work to be done to continue to clean up the air.

Ways to Reduce Air Pollution

How can air pollution be reduced? Using less fossil fuel is one way to lessen pollution. Some examples of ways to conserve fossil fuels are:

• Riding a bike or walking instead of driving.
• Taking a bus or carpooling.
• Buying a car that has greater fuel efficiency.
• Turning off lights and appliances when they are not in use.
• Using energy efficient light bulbs and appliances.
• Buying fewer things that are manufactured using fossil fuels.

All these actions reduce the amount of energy that power plants need to produce.

Developing alternative energy sources is important. Think back to the chapter, Earth’s Energy. What are some of the problems facing wider adoption of alternative energy sources?

• The technologies for several sources of alternative energy, including solar and wind, are still being developed.
• Solar and wind are still expensive relative to using fossil fuels. The technology needs to advance so that the price falls.
• Some areas get low amounts of sunlight and are not suited for solar. Others do not have much wind. It is important that regions develop what best suits them. While the desert Southwest will need to develop solar, the Great Plains can use wind energy as its energy source. Perhaps some locations will rely on nuclear power plants, although current nuclear power plants have major problems with safety and waste disposal.

Sometimes technological approaches are what is needed.

National Geographic videos exploring energy conservation are found in Environment Videos, Energy: http://video.nationalgeographic.com/video/player/environment/.

• Alternative Energy
• Fuel Cells
• Solar Power

What you can do to your home to help reduce energy use: http://www.youtube.com/watch?v=6h8QjZvcp0I. A very simple thing you can do to conserve energy is discussed in “This Bulb,” http://www.youtube.com/watch?v=FvOBHMb6Cqc.

Reducing Air Pollution from Vehicles

Reducing air pollution from vehicles can be done in a number of ways.

• Breaking down pollutants before they are released into the atmosphere. Motor vehicles emit less pollution than they once did because of catalytic converters (Figure below). Catalytic converters contain a catalyst that speeds up chemical reactions and breaks down nitrous oxides, carbon monoxide, and VOCs. Catalytic converters only work when they are hot, so a lot of exhaust escapes as the car is warming up.

• Making a vehicle more fuel efficient. Lighter more streamlined vehicles need less energy. Hybrid vehicles have an electric motor and a rechargeable battery. The energy that would be lost during braking is funneled into charging the battery, which then can power the car. The internal combustion engine only takes over when power in the battery has run out. Hybrids can reduce auto emissions by 90% or more, but many models do not maximize the possible fuel efficiency of the vehicle.

A plug-in hybrid is plugged into an electricity source when it is not in use, perhaps in a garage, to make sure that the battery is charged. Plug-in hybrids run for a longer time on electricity and so are less polluting than regular hybrids. Plug-in hybrids are beginning to become available in 2010.

• Developing new technologies that do not use fossil fuels. Fueling a car with something other than a liquid organic-based fuel is difficult. A fuel cell converts chemical energy into electrical energy. Hydrogen fuel cells harness the energy released when hydrogen and oxygen come together to create water (Figure below). Fuel cells are extremely efficient and they produce no pollutants. But developing fuel-cell technology has had many problems and no one knows when or if they will become practical.

Reducing Industrial Air Pollution

Pollutants are removed from the exhaust streams of power plants and industrial plants before they enter the atmosphere. Particulates can be filtered out, and sulfur and nitric oxides can be broken down by catalysts. Removing these oxides reduces the pollutants that cause acid rain.

Particles are relatively easy to remove from emissions by using motion or electricity to separate particles from the gases. Scrubbers remove particles and waste gases from exhaust using liquids or neutralizing materials (Figure below). Gases, such as nitrogen oxides, can be broken down at very high temperatures.

Gasification is a developing technology. In gasification, coal (rarely is another organic material used) is heated to extremely high temperatures to create syngas, which is then filtered and the energy goes on to drive a generator. Syngas releases about 80% less pollution than regular coal plants, and greenhouse gases are also lower. Clean coal plants do not need scrubbers or other pollution control devices. Although the technology is ready, clean coal plants are more expensive to construct and operate. Also, heating the coal to high enough temperatures uses a great deal of energy, so the technology is not energy efficient. In addition, large amounts of the greenhouse gas CO₂ are still released with clean coal technology. Nonetheless, a few of these plants are operating in the United States and around the world.

Reducing Ozone Destruction

One success story in reducing pollutants that harm the atmosphere concerns ozone-destroying chemicals. In 1973, scientists calculated that CFCs could reach the stratosphere and break apart. This would release chlorine atoms, which would then destroy ozone. Based only on their calculations, the United States and most Scandinavian countries banned CFCs in spray cans in 1978.

More confirmation that CFCs break down ozone was needed before more was done to reduce production of ozone-destroying chemicals. In 1985, members of the British Antarctic Survey reported that a 50% reduction in the ozone layer had been found over Antarctica in the previous three springs. Two years later, the “Montreal Protocol on Substances that Deplete the Ozone Layer” was ratified by nations all over the world.

The Montreal Protocol controls the production and consumption of 96 chemicals that damage the ozone layer (Figure below). Hazardous substances are phased out first by developed nations and one decade later by developing nations. More hazardous substances are phased out more quickly. CFCs have been mostly phased out since 1995, although were used in developing nations until 2010. Some of the less hazardous substances will not be phased out until 2030. The Protocol also requires that wealthier nations donate money to develop technologies that will replace these chemicals.

Had CFCs not been phased out, by 2050 there would have been 10 times more skin cancer cases than in 1980. The result would have been about 20 million more cases of skin cancer in the United States and 130 million cases globally.

Since CFCs take many years to reach the stratosphere and they can survive there a long time before they break down, the ozone hole will probably continue to grow for some time before it begins to shrink. The ozone layer will reach the same levels it had before 1980 around 2068 and 1950 levels in one or two centuries.

Reducing Greenhouse Gases

Climate scientists agree that climate change is a global problem that must be attacked by a unified world with a single goal. All nations must come together to reduce greenhouse gas emissions. However, getting nations to agree on anything has proven to be difficult. A few ideas have been proposed and in some nations are being enacted.

International Agreements

The first attempt to cap greenhouse gas emissions was the Kyoto Protocol, which climate scientists agree did not do enough in terms of cutting emissions or in getting nations to participate. The Kyoto Protocol set up a cap-and-trade system. Cap-and-trade provides a monetary incentive for nations to develop technologies that will reduce emissions and to conserve energy. Some states and cities within the United States have begun their own cap-and-trade systems.

The United Nations Climate Change Conference meets in a different location annually. Although recommendations are made each year, the group has not gotten the nations to sign on to a binding agreement. By doing nothing we are doing something – continuing to raise greenhouse gas levels and failing to prepare for the coming environmental changes.

How bad could a few degrees be? National Geographic has a set of videos about what to expect if temperature rises by each of these amounts by degree Celsius.

• 1°: http://www.youtube.com/watch?v=2_ZQRIsn2pA
• 2°: http://www.youtube.com/watch?v=P-0_gDXqYeQ
• 3°: http://www.youtube.com/watch?v=6rdLu7wiZOE
• 4°: http://www.youtube.com/watch?v=skFrR3g4BRQ
• 5°: http://www.youtube.com/watch?v=7nRf2RTqANg
• 6°: http://www.youtube.com/watch?v=O8qmaAMK4cM

Carbon Tax

The easiest and quickest way is to reduce greenhouse gas emissions is to increase energy efficiency. One effective way to encourage efficiency is financial. A carbon tax can be placed on CO₂ emissions to encourage conservation. The tax would be placed on gasoline, carbon dioxide emitted by factories, and home energy bills so people or businesses that emit more carbon would pay more money. This would encourage conservation since when people purchase a new car, for example, they would be more likely to purchase an energy efficient model. The money from the carbon tax would be used for research into alternative energy sources. All plans for a carbon tax allow a tax credit for people who cannot afford to pay more for energy so that they do not suffer unfairly.

New technologies can be developed, such as renewable sources that were discussed in the chapter,Earth’s Energy. Biofuels can replace gasoline in vehicles, but they must be developed sensibly (Figure below). So far much of the biofuel is produced from crops such as corn. But when food crops are used for fuel, the price of food goes up. Modern agriculture is also extremely reliant on fossil fuels for pesticides, fertilizers, and the work of farming. This means that not much energy is gained from using a biofuel over using the fossil fuels directly. More promising crops for biofuels are now being researched. Surprisingly, algae is being investigated as a source of fuel! The algae can be grown in areas that are not useful for agriculture, and it also contains much more usable oil than crops such as corn.

Carbon Capture and Sequestration

If climate change becomes bad enough, people can attempt to remove greenhouse gases from the atmosphere after they are emitted. Carbon sequestration occurs naturally when carbon dioxide is removed from the atmosphere by trees in a forest. One way to remove carbon would be to plant more trees, but unfortunately, more forest land is currently being lost than gained.

Carbon can also be artificially sequestered. For example, carbon can be captured from the emissions from gasification plants and then stored underground in salt layers or coal seams. While some small sequestration projects are in development, large-scale sequestration has not yet been attempted.

This type of carbon capture and sequestration comes under the heading of geoengineering. There are many other fascinating ideas in geoengineering that people have proposed that are worth looking at. One wild example is to shadow the planet with large orbiting objects. A large mirror in orbit could reflect about 2% of incoming solar radiation back into space. These sorts of solutions would be expensive in cost and energy.

Just as individuals can diminish other types of air pollution, people can fight global warming by conserving energy. Also, people can become involved in local, regional, and national efforts to make sound choices on energy policy.

Lesson Summary

• Air pollutants can be reduced in many ways. The best method is to not use energy that produces the pollutants through conservation or increasing energy efficiency.
• Alternative energy sources are another good way to reduce pollution. Most of these alternate energy technologies are still being refined (solar, wind) and some have other problems associated with them (nuclear, biofuels).
• Pollutants can be removed from an exhaust stream by being filtered out or broken down. Some pollutants, such as CFCs, are best not released at all.

Review Questions

1. Since the Clean Air Act was passed in 1970, why is the air still not clean?

2. What are some ways that you can conserve energy?

3. How does reducing air pollutants, as described in the Clean Air Act of 1970, affect greenhouse gas emissions?

4. What has to be done before alternative energy sources can replace fossil fuels?

5. What are catalytic converters?

6. Why are hybrid vehicles more energy efficient than regular vehicles powered by internal combustion engines?

7. Why aren’t fuel-cell vehicles widely available yet?

8. How does a cyclone reduce particulate pollution?

9. How can coal power be made so that it has nearly zero carbon contribution to the atmosphere?

10. Why is it that the ozone hole will not be healed for several decades?

11. Many people think that biofuels are the solution to a lot of the problems of climate change, but others disagree. What requirements would biofuels have to meet if they were to be really effective at replacing gasoline in motor vehicles?

Points to Consider

• Why is it important to reduce air pollution?
• What can you do in your own life to reduce your impact on the atmosphere?
• Why is a worldwide effort needed to reduce the threat of global climate change?