Module 4: Environmental Problems of Energy Resources

Primary Resources and Environmental Impact

  • 99% of worldwide electrical energy generation relies on primary resources.
  • Primary resources include fossil fuels, hydroelectric power, and nuclear energy.
  • Significant environmental concerns arise from using these resources.

Environmental Problems

  • Use of primary resources leads to:
    • Acid rain
    • Respiratory illnesses
    • Nuclear leakage
    • Global warming
    • Harm to fish and animals

Clean Air Composition

  • Delicate balance necessary for human, animal, and vegetation health:
    • Nitrogen (N2): 78.1%
    • Oxygen (O2): 21%
    • Argon (Ar): 0.9%
    • Carbon Dioxide (CO2): 330 parts per million (ppm)
    • Neon (Ne): 18 ppm
    • Water Vapor (H2O)
    • Trace amounts: krypton, helium, methane, hydrogen, nitrous oxide, xenon, ozone

Impact of Fossil Fuels

  • Fossil fuels, especially raw coal, are major air pollution sources.
  • A single raw coal power plant without proper filtering can heavily pollute a city the size of New York.
  • Pollutants can combine, creating a synergistic effect among pollutants.

US Environmental Protection Agency (EPA)

  • EPA establishes National Ambient Air Quality Standards (NAAQS) to regulate pollutants.
  • NAAQS covers six pollutants:
    • Carbon Monoxide (CO)
    • Lead (Pb)
    • Nitrogen Dioxide (NO2)
    • Particulate Matter (PM)
    • Ozone (O3)
    • Sulfur Dioxide (SO2)
  • Two types of standards:
    • Primary: Protects health of sensitive populations (asthmatics, children, elderly)
    • Secondary: Protects general public health, visibility, animals, crops, vegetation, and buildings
  • Areas exceeding standards are classified as "non-attainment," leading to federal regulations and deadlines for compliance.

National Ambient Air Quality Standards Examples

  • Carbon Monoxide (CO):
    • Primary: 9 ppm (10 mg/m³) not to be exceeded more than once per year (8-hour average)
    • Secondary: None
  • Lead (Pb): Specific standards exist
  • Nitrogen Dioxide (NO2): Specific standards exist
  • Particulate Matter:
    • PM 2.5-10 μm: Specific standards exist for annual and 24-hour exposure
    • PM < 2.5 μm: Specific standards exist
  • Ozone and Sulfur Dioxide: Also have specific NAAQS standards

Air Pollution from Fossil Fuel Power Plants

  • Fossil fuel power plants burn oil, gas, or coal, emitting harmful gases.
  • Emitted gases include:
    • Sulfur oxides (SO2, SO3)
    • Carbon dioxide (CO2)
    • Nitrogen oxides (NOx)
    • Ashes
    • Tropospheric ozone (O3)

Sulfur Dioxide (SO2)

  • Fossil fuels contain sulfur, which, when burned, combines with oxygen to form SO2 and SO3.
  • SO2 is corrosive, acidic, colorless gas with suffocating odor, causing health problems.
  • Concentrations of 2 ppm can be easily detected by odor.
  • Coal power plants emit approximately 14 pounds of sulfur oxides per megawatt hour.
  • Natural gas emits significantly less sulfur.
  • High SO2 levels damage the upper respiratory tract and lung tissue, especially affecting the young, old, and asthmatics.
  • Historical events like the 1952 London smog event and Gulf War oil fires demonstrate the dangers.

Rapid Effects of SO2

  • SO2 has rapid effects, causing respiratory and cardiovascular problems within minutes of exposure.
  • Even small concentrations (parts per million) increase health risks.
  • Coal-fired power plants can emit 7 kg of SO_2 per MWh.
  • Natural gas power plants emit only about 5 grams per MWh.
  • Worldwide, power plants release an estimated 20 million tons of SO_2.
  • Regulations and penalties imposed to reduce emissions led to declines in some regions.
  • Desulfurization of coal and conversion to natural gas are encouraged.
  • Sulfur emissions remain high in Eastern Europe, Asia, Africa, and South America.

Nitrogen Oxides (NOx)

  • Nitrogen oxides are harmful gases produced by burning fossil fuels.
  • Coal and natural gas power plants produce about 2 kg per MWh of nitrogen dioxide (NO2).
  • NO2 is a toxic, highly reactive oxidant that irritates eyes, nose, throat, and respiratory tract.
  • High concentrations can cause respiratory infections and chronic bronchitis.
  • NO2 plays a role in smog and acid rain formation.
  • Emissions are comparable between coal and natural gas.

Ozone (O3)

  • Found at two altitudes:
    • Troposphere (up to 10 km)
    • Stratosphere (10-50 km)
  • Stratospheric ozone protects Earth by absorbing ultraviolet radiation.
  • Chlorofluorocarbons (CFCs) deplete the ozone layer. One chlorine atom can destroy 100,000 ozone molecules.
  • CFCs banned in the US (1978) and most countries (refrigerants, aerosol products).
  • Tropospheric ozone forms when NO2 is released by industrial plants.
  • It produces smog, irritates lungs, damages plants, and makes asthmatics sensitive to SO_2.
  • Solar radiation converts NO2 into nitric oxide (NO) and oxygen (O), which combines with O2 to form ozone (O3).
  • Nitric oxide can also form during lightning storms.
  • Troposphere ozone is harmful and can be recycled back to nitrogen dioxide and oxygen.

Tropospheric Ozone Imbalance

  • Balance exists where ozone is formed and destroyed, keeping concentrations low when NO is available.
  • Hydrocarbons from automobile emissions react with NO to form organic radicals, reducing the amount of NO available to destroy tropospheric ozone.
  • This increases ozone concentration.
  • Formula: k1 to form ozone, k2 to destroy ozone. If the values are not balanced, ozone is left.

Effects of Tropospheric Ozone

  • Danger level at 0.3 ppm.
  • 0.3 ppm causes nasal and throat irritation, 0.5 ppm could cause lung edema.
  • 1 ppm results in smog alert two.

Acid Rain

  • Sulfur and nitrogen dioxide produced by burning fossil fuels are the main ingredients.
  • Sulfur dioxide reacts with oxygen to form sulfur trioxide (SO_3).
  • Sulfur trioxide combines with water vapor (H2O) in clouds to generate sulfuric acid (H2SO_4).
  • Nitrogen dioxide interacts with water, forming nitric acid (HNO_3).

Effects of Acid Rain

  • Damages crops, agriculture, land, and structures.
  • Increases water acidity, affecting fish populations.
  • Damages limestone structures.

pH Scale

  • Quantifies acidity using the potential of hydrogen (pH).
  • It is the negative logarithmic measure of hydrogen ion (H^+) concentration in moles per liter.

pH Values

  • Pure water: pH 7 (neutral).
  • Less than 7: Acidic solution. Between 0 and 1 would be acids used in batteries. A clean rain goes for pH 5-6
  • Acid Rain: Less Than pH 5 which could fall to levels around pH 4.3 (most acidic rain recorded)
  • Greater than 7: Alkaline/Basic solution.

Carbon Dioxide (CO2)

  • Colorless, odorless, slightly acidic greenhouse gas.
  • Nature recycles CO2 through water, animals, and plants.
  • Industrial activities increase CO2 concentration, contributing to global warming.
  • Coal-fired power plants produce 1,000 kg CO2 per MWh (1 ton).
  • Natural gas produce half of CO2 production from coal, around 500 kg per MWh.

Greenhouse Effect and Global Warming

  • CO_2 is a limited-effect greenhouse gas with shorter atmospheric presence, other gases like chlorofluorocarbons (CFCs) and nitrous oxide are worse.
  • One molecule of CFC has the effect of 10,000 molecules of CO_2.
  • These gases remain in the atmosphere for very long periods.

Global Warming Process

  • Earth's temperature is determined by solar energy received and energy radiated back into space.
  • Greenhouse gases form a thermal blanket, reducing radiated energy causing increased heat, which is the greenhouse effect.
  • Imbalance leads to increased temperatures.

Greenhouse Gases

  • Include carbon dioxide (CO2), chlorofluorocarbons (CFC), methane (CH4), nitrous oxide (N2O), ozone (O3).
  • Global warming can melt glaciers, raise sea levels, and change rain and wind patterns.
  • Global temperatures have risen by about 1 degree centigrade during the last century.
  • Stratospheric ozone and sulfates cool the atmosphere, some may argue that global warming may not be as a severe, such debate is still ongoing.

Ashes

  • Small particles (0.01 to 50 μm diameter) suspended in the air.
  • Combustion in plants releases 7 million tons of ash yearly.
  • Ashes contain metals such as iron, titanium, zinc, lead, nickel, arsenic, and silicon.
  • Ash affects breathing, weakens immune systems, and worsens cardiovascular disease.
  • Particles smaller than 10 μm reach the lower respiratory tract.
  • Filtering devices reduce ash discharge - wet scrubber systems and fabric filter systems.

Legionella

  • Harmful bacteria living in cooling towers, hot water systems, freshwater ponds, and creeks.
  • Causes Legionnaire's disease (a form of pneumonia).
  • Water droplets carrying Legionella can drift and cause infection.
  • Mist eliminators and algaecides are used in cooling towers to prevent growth. Expensive, so not always implemented worldwide.

Environmental Concerns of Hydroelectric Power Plants

  • Flooding
  • Altered Water Flow
  • Silt/Sediment
  • Oxygen Depletion
  • Impacts to Fish

Flooding Impacts.

  • Land upstream is flooded when building a dam
  • Decaying vegetation underneath floodwaters leads to gas emissions.
  • Dangerous substances such as mercury accumulate in the fish.
  • People may be displaced from homes by the flooding

Altered Water Flow Impacts

  • Water quality and rate are affected.

Silt and Sedimentation Impacts

  • Prevents fertilization of surrounding lands
  • Shore erosion may occur
  • Amount of stored water in the reservoir can be affected.

Oxygen Depletion Environmental Concerns

  • Oxygen could be reduced at the bottom of the reservoir which will alter the plants and fish population there.

Fish Environmental Concerns

  • River flow alteration can affect the migration of certain fish.
  • Turbines also injure/kill fish.

Environmental Concerns for Nuclear Power Plants

  • Radioactive release during normal operation is a great source of concern for plants.
  • Reactor explosions also a concern, as well as disposal of radioactive waste.

Public Concerns with Nuclear Power

  • Public is highly concerned about the nuclear accidents at the three mile island, Chernobyl, and Fukushima.
  • Accidents increased pressure to have safety regulations for nuclear power.

Nuclear Power Concerns

  • Hydrogen explosion causes a potential risk for nuclear power.
  • When the temperature reaches to 1,200 degrees Celsius, the hydrogen in the water Splits and then it is trapped at the ceiling of the reactors.
  • Then when the hydrogen Ignites, and exclusion might damage the containers.
  • Radioactive steam may be released into the air.

High Temperature Nuclear Power Concerns

  • At 2,400 degree uranium fuel will melt, and may pollute water tables.
  • Damage to the containment structure may occur from the heat.
  • Radioactive steam may be released as well.