Earth’s Changing Environment Lecture 4 Improving Air Quality

Emission of Pollutants Point Source Point Source Non-point Source Non-point Source

Emissions From Automobiles (non-point source)

Automobile Emission Standards Set by EPA (g/mile) Pollutant VOC NOx CO

How are emission standards achieved?

Catalytic Converter Converts VOC, CO, NOx -> H2O, N2, O2, CO2 Converts VOC, CO, NOx -> H2O, N2, O2, CO2 Catalysts are platinum, palladium, rhodium or a ceramic. Catalysts are platinum, palladium, rhodium or a ceramic. Add $500 to cost of car. Add $500 to cost of car.

Mathematical Example 1 There are 220 million cars, light trucks, vans, and SUVs on the road in the US. There are 220 million cars, light trucks, vans, and SUVs on the road in the US. Estimate the approximate national investment in catalytic converters. Estimate the approximate national investment in catalytic converters. 2.2 x 10 8 vehicles x 5.0 x 10 2 $/vehicles 2.2 x 10 8 vehicles x 5.0 x 10 2 $/vehicles = 11 x $ = 11 x $ = 110 x 10 9 $ = 11 x $ = 11 x $ = 110 x 10 9 $ = $110 billion (Compare to trillions in vehicles) = $110 billion (Compare to trillions in vehicles)

Mathematical Example 2 There are 220 million cars, light trucks, vans, and SUVs on the road in the US. There are 220 million cars, light trucks, vans, and SUVs on the road in the US. Each vehicle travels an average of 13,000 mi/year. Each vehicle travels an average of 13,000 mi/year. By what amount were NOx emissions reduced by switching from the 1975 to the 1998 standard? By what amount were NOx emissions reduced by switching from the 1975 to the 1998 standard? 2.2 x 10 8 vehicles x 1.3 x 10 4 mi/vehicle x ( ) g/mi 2.2 x 10 8 vehicles x 1.3 x 10 4 mi/vehicle x ( ) g/mi = 7.7 x g = 7.7 x g = 7.7 x 10 9 kg = 7.7 x g = 7.7 x g = 7.7 x 10 9 kg = 7.7 x 10 6 MT (metric tons) = 7.7 x 10 6 MT (metric tons) Would still emit 1.1 million metric tons. Would still emit 1.1 million metric tons.

Command and Control Strategy Automobile emission standards are an example of the “Command and Control” strategy. Emission standards are set and enforced by EPA. Automobile emission standards are an example of the “Command and Control” strategy. Emission standards are set and enforced by EPA.

Tailpipe Emissions Testing in San Antonio Tailpipe Emissions Testing in San Antonio Tailpipe Emissions Testing is still being considered for SA. Tailpipe Emissions Testing is still being considered for SA. $40 per vehicle annually. $40 per vehicle annually. Strongly opposed by the local community. Strongly opposed by the local community.

Mathematical Example 3 There are 1 million cars in SA. There are 1 million cars in SA. Each vehicle travels an average of 13,000 mi/year. Each vehicle travels an average of 13,000 mi/year. Assume 90% of cars meet the 1998 NOx standard, but 10% only meet the 1975 standard. Assume 90% of cars meet the 1998 NOx standard, but 10% only meet the 1975 standard. How many tons of NOx does each group of cars emit? How many tons of NOx does each group of cars emit? 0.90 x 1 x 10 6 vehicles x 1.3 x 10 4 mi/vehicle x 0.4 g/mi 0.90 x 1 x 10 6 vehicles x 1.3 x 10 4 mi/vehicle x 0.4 g/mi = 0.46 x g = 4.6 x 10 9 g = 4.6 x 10 3 metric tons = 0.46 x g = 4.6 x 10 9 g = 4.6 x 10 3 metric tons 0.10 * 1 x 10 6 vehicles x 1.3 x 10 4 mi/vehicle x 3.4 g/mi 0.10 * 1 x 10 6 vehicles x 1.3 x 10 4 mi/vehicle x 3.4 g/mi = 0.44 x g = 4.4 x 10 9 g = 4.4 x 10 3 metric tons = 0.44 x g = 4.4 x 10 9 g = 4.4 x 10 3 metric tons So, 10% of the cars emit half the pollution. So, 10% of the cars emit half the pollution.

Have EPA Strategies Worked for Pollution Emission by cars? Pollutant VOC 16.9 (41*) 4.9 NOx 11.5 (28*) 8.2 CO 163 (400*) 75 Emission by On-Road Vehicles ( million short tons) Estimate of current value with no pollution control program, business as usual. Assuming 143 percent increase in vehicle miles. Estimate of current value with no pollution control program, business as usual. Assuming 143 percent increase in vehicle miles.

Emissions From Power Plants (point sources)

Power Plant Emissions 1970 power plant emission 17 million tons 1970 power plant emission 17 million tons Acid Rain Program set 9.0 million ton cap by 2010 Acid Rain Program set 9.0 million ton cap by 2010 Use Cap and Trade strategy.

Cap and Trade To reduce SO2 emissions from 3,208 Electric Utilities. To reduce SO2 emissions from 3,208 Electric Utilities. Utilities are assigned allowances - permission to emit a ton of sulfur dioxide Utilities are assigned allowances - permission to emit a ton of sulfur dioxide Utilities can sell unused allowances or carry them over into the next year. Utilities can sell unused allowances or carry them over into the next year.

Scrubbers Flue-gas desulfurization passes exhaust gas through slurries of limestone (calcium carbonate) to form calcium sulfates and removing the SO2. Disposing of the calcium sulfates is a problem. Flue-gas desulfurization passes exhaust gas through slurries of limestone (calcium carbonate) to form calcium sulfates and removing the SO2. Disposing of the calcium sulfates is a problem.

Other Techniques Tall Chimneys Tall Chimneys Using Low-Sulfur coal Using Low-Sulfur coal Fluidized Bed Combustion – mixes limestone in the boiler Fluidized Bed Combustion – mixes limestone in the boiler

Economics Cost of Scrubber: $50 to $80 per installed kW Cost of Scrubber: $50 to $80 per installed kW San Antonio’s Electric Utility, CPS, has 1,425 MW capacity in coal-burning plants San Antonio’s Electric Utility, CPS, has 1,425 MW capacity in coal-burning plants Assuming $50 per installed kW, estimated the cost of scrubbers for this total capacity. Assuming $50 per installed kW, estimated the cost of scrubbers for this total capacity. $50 x 1,425,000 kW = $70 million $50 x 1,425,000 kW = $70 million

New Source Review NSR states that if a plant makes any modifications to its operation that increases its pollution emissions, it must install state of the art or best available emissions control equipment. NSR states that if a plant makes any modifications to its operation that increases its pollution emissions, it must install state of the art or best available emissions control equipment. The Bush Administration has recently asked for changes in EPA policy that would make it easier for power plants to make modification in older plants without installing new equipment. The Bush Administration has recently asked for changes in EPA policy that would make it easier for power plants to make modification in older plants without installing new equipment. An appeals court ruled in favor of environmental groups and 14 states. These rule changes have been blocked. An appeals court ruled in favor of environmental groups and 14 states. These rule changes have been blocked.

The Clean Air Act Worked!

Emissions have declined.

Air Quality has improved.

But, ozone improvements have leveled off.

Because VOCs declines have slowed.

50% of NOx emissions are from autos and this has leveled off. 22% of NOx emissions are from power plants and this has declined by 22%.

What about Acid Rain?

SO2 emissions have declined.

NOx emissions from power plants have declined, but emissions from other sources have not declined as much.

Sulfate Deposition has decreased dramatically.

Nitrogen Deposition has changed little.

Conclusions Clean Air Act has been very successful Clean Air Act has been very successful But, Ozone problems persist. But, Ozone problems persist. Acid rain problems persist. Acid rain problems persist. NOx emission from autos is a major contributor to these problems NOx emission from autos is a major contributor to these problems