Exam 4

U.S. Clean Air Act criteria pollutants

Sulfur Dioxide
Nitrogen Oxides
Carbon Monoxide
Ozone (VOCs)
Lead
Particulates

global warming potential

• measure of an individual molecule's long-term impact on atmospheric temperature
• (1) capacity to absorb infrared light and retain heat
• (2) atmospheric residence time

Ocean thermal energy conversion (OTEC) systems

exploit the sharp differences in temperature between surface water and deeper water to generate electricity

Air Quality

amounts of gases and small particles in the atmosphere that influence ecosystems or human well-being

Air Pollution

refers to gases or particles that are present in high enough concentrations to cause harm

Composition of the Atmosphere

78% nitrogen, 21% oxygen, 1% other gases

Sources of carbon dioxide in the atmosphere

Burning fossil fuels and other carbon containing materials, respiration and decomposition

Sources of nitrogen oxides

fossil fuel burning

Volatile Organic Compounds (VOCs)

organic compounds that become vapors at typical atmospheric temperatures
-solvents, paints, gasoline, car exhaust

methane

most abundant natural volatile organic compound

Particulate Matter (PM)

Solid or liquid particles suspended in air; also known as particles and particulates or aerosols

natural sources of air pollution

• volcanic eruptions (sulfur components)
• radon (released from U-bearing rocks)
• aerosols (sea salt, pollen, dust, smoke)

Primary air pollutants

• substances directly emitted into the atmosphere
• Can be natural or man-made
• Examples:
• Hg (combustion, volcanoes)
• CO, SO2 (fossil fuel burning)
• chlorofluorocarbons (CFCs; industrial processes)

Secondary air pollutants are formed by

primary pollutants chemically reacting with other compounds in the atmosphere
• Ozone (O3; produced from NO and O2 + sunlight)
• Smog (complex aerosol, forms from combining water droplets, smoke, and chemical mixture + sun)

Photochemicals are secondary pollutants whose formation is facilitated by _____.

sunlight

Point sources

• stationary, localized sources (smokestack of a factory)
• Each point source has the potential to produce large amounts of pollutants

Non-point sources

• may be mobile (cars) or stationary (residential fireplaces and agriculture)
• Cumulative effect: each source produces relatively small amounts

Atmospheric lifetime

average time a pollutant remains in the atmosphere
• depends on the chemical stability of a pollutant and factors that influence its removal from the air
• Reactive trace gases: Ammonia (1-2 h), NO (1 day), CO (>2 months)
• Inert gases: >1000 years

Dry deposition occurs when ____.

nonliquid particles are removed from the atmosphere by gravity, larger particles (high deposition rate/shorter lifetime)

Wet deposition

• trace gases and particles are captured in raindrops, snowflakes, or droplets of fog
• the more soluble a pollutant is in water, the more prone it is to wet deposition

Ozone

• pollutant in the troposphere, damages lung tissue
• essential to health in stratosphere, filters most of the UV radiation

ozone hole

an area of the ozone layer (near the poles) that is seasonally depleted of ozone

Montreal Protocol

(1987) phase-out of ozone depleting substances

Three types of air pollution

• Acid deposition
• Heavy metal pollution
• Smog

acid deposition

• dispersion of acid-containing gases, aerosols
-Sulfur oxides and nitrogen oxides combine with oxygen and water to form sulfuric acid and nitric acid
-rain onto soils, plants, buildings, and bodies of water

Sources of acid deposition

• Coal-fired power plants and metal smelters
• NOX emitted by cars and power plants
• SO2 emissions high in industrial cities

Natural sources of heavy metal pollution

volcanoes, sea salt, and dust, fires

Anthropogenic sources of heavy metal pollution

• Combustion of fossil fuels, waste incineration, and industrial processes such as metal smelting

Smog

• gases and aerosols, which are a complex mixture of both primary and secondary pollutants

Major Air Pollutants

• Sulfur dioxide - acid rain, health damage, visibility reduction
• Nitrogen oxides - acid rain, eutrophication, growth of weedy species
• Carbon monoxide - inhibited respiration
• Lead and mercury - neurological damage
• Chlorofluorocarbons - ozone depletion
• Particulate matter - lung damage, cancer
• Volatile organic compounds - CO, CO2 production in the atmosphere

photochemical smog

air pollution that forms from the interaction between chemicals in the air and sunlight
• primary pollutants come from the exhaust of vehicles (NO, VOCs)
• react with oxygen and water vapor to form secondary pollutants (ozone and nitrogen dioxide --brownish color)

industrial smog

• mainly composed of pollutants released during coal burning
• carbon monoxide (CO), sulfur dioxide (SO2), and particles of carbon soot

Air Quality Index (AQI)

a measure of local air quality and what it means for health
• particulate matter is subdivided by size
• standards are defined in terms of exposure over a specific time duration

Examples of climate variables

• Temperature
• Precipitation
• Humidity (moisture in the air)

Milankovitch cycles

Changes in the shape earth's orbit and tilt that cause glacial periods and interglacial periods.

carbon dioxide equivalent

• measure used to compare the emissions of various greenhouse gases based on how long they stay in the atmosphere and how much heat they can trap

Human-induced causes of global warming

• Deforestation for agriculture (reduces CO2 in trees)
• Domestication of cows and sheep (adding CH4)
• Burning of wood
• Burning of fossil fuels (coal, petroleum, natural gas)

primary energy

energy contained in natural resources (coal, oil, sunlight, wind, uranium)

Consumption

• amount of a primary energy source that is actually used during a particular time

Nonrenewable Energy

• derived from sources that exist in limited quantities or that are replenished at rates below the rate of consumption

Coal Types

lignite, sub-bituminous, bituminous, anthracite

fly ash

The residue collected from the chimney or exhaust pipe of a furnace, contains toxic chemicals

alternative fossil fuels

tar sands
• Deposits near the surface
• Accessed by process similar to open-pit mining, boreal forest is cleared, sand is removed and processed
• ~2 t of tar sand produce one barrel of oil (42 gallons)

primary oil recovery

during drilling; the extraction of crude oil pushed to the surface by built-up pressure in the reservoir, first 20%

Advantages of renewable energy

cleaner, better for the environment, less pollution, abundant

Active solar technologies

use mechanical devices to heat water and buildings or electrical devices to generate electricity (solar power)
• Rooftop solar heating panels
• Lens collectors, reflective light pipes, hybrid solar lighting
• Photovoltaic (PV) technology:
• Concentrating solar power (CSP) systems

Concentrating solar power (CSP) systems

• large-scale projects use mirrors to concentrate the sun's rays on a tower or a series of pipes that hold water or another fluid ---heats fluid, produces steam --- turbine/electricity

Disadvantages of solar energy

• Intermittent
• Geographical limitations
• High upfront cost (~$20000; tax incentives through 2021, 30%)
• Production is energy- and material-intensive; electricity from fossil fuels (GHG debt)
• Production requires hazardous materials and heavy metals

geothermal energy

refers to heat energy that is generated and stored in the Earth itself

Effects of air pollution on human health

• Irritate and damage tissues in eyes and respiratory passages
• Inflammation impairs lung function, and triggers cardiovascular problems
Chronic Health Effects:
• Bronchitis (Persistent inflammation of airways in the lung that causes mucus build-up and muscle spasms constricting airways)
• Emphysema (Irreversible obstructive lung disease in which airways become permanently constricted and alveoli are damages or destroyed)

US Clean Air Act of 1970

set standards for six pollutants that significantly threaten human well-being, ecosystems, and/or structures: sulfur dioxide, nitrogen oxides, carbon monoxide, particulate matter, tropospheric ozone, and lead

The U.S. Clean Air Act Amendments of 1990 require:

development of automobiles with lower nitrogen oxide and hydrocarbon emissions

greenhouse effect

• greenhouse gases trap infrared radiation (IR) energy in the atmosphere, preventing it from escaping
• Earth is receiving more energy than it loses into space
• Excess energy is then re-radiated back to the Earth's surface causing an increase in overall temperatures (Global Warming)

Greenhouse Gases (GHGs)

• greenhouse gases are natural or human-produced gases that trap heat in the atmosphere and contribute to the greenhouse effect
• water vapor, carbon dioxide, methane, nitrous oxide, and fluorinated gases (CFCs)

Paleoclimatology

study of past climates

global warming

• global annual average temperature anomaly shows a steady increase in the temperature of Earth's atmosphere since 1880

weather

atmospheric conditions of a small region over a short period of time

climate

atmospheric conditions of a large region over long periods of time

climate change

long-term variations in climatic variables (T, precipitation)s

Natural causes of climate change

1. Orbital changes/tilt and orientation of Earth's rotational axis:
2. Ocean current changes
3. Plate Tectonics
• Volcanoes
• Position of continents
4. Atmospheric composition
5. Variations in output by the Sun

eccentricity

changes in the orbital shape (spherical versus elliptical)

Obliquity

tilt of the Earth's axis

Oscillations

• changes in sea surface temperatures over large regions that occur over intervals of years or decades

Consequences of ocean current changes

• thunderstorms, increased rainfall
• floods
• droughts

solar forcing

radiative forcing caused by changes in incoming solar radiation

How do we study past climates?

• Ice Cores
• Tree rings
• Pollen
• Rock or sediment record

Effects of global warming

• Melting of polar ice sheets (Greenland and Antarctica) and alpine glaciers
• Overall rise in sea level - coastal flooding
• Changes in the hydrologic cycle
• Changes in the oceanic environment
• Shifts in oceanic circulation
• Increase in the severity of weather events
• Hurricanes, tornadoes, droughts, wildfires
• Disruptions to agriculture
• Effects on human health

Effects of global warming on the ocean

• Sea surface temperatures are warming
• Sea level is rising
• Seawater is becoming more acidic
• Lake Temperatures Rise
• Arctic sea ice is melting
• Melting of Greenland Ice Sheet

How can we reduce impacts of Global Warming?

• Reduce the amount of fossil fuel use
• Conservation of certain ecosystems
• Carbon sequestration

energy conversion

• change of primary energy in other forms of energy, that is, secondary energy

End use

final application of energy (e.g., running an appliance or driving a car)

Primary energy end use

• Coal: 80% electricity production, 1% transportation
• Oil: 65% transportation, <1% electricity production
• Natural gas: 35% electricity production, remainder: heating, cooking, other applications in industry, homes, businesses

energy conversion efficiency

• percentage of primary source energy that is captured in a secondary form of energy
• Example: coal is used to generate electricity, 70% of energy is transformed into unused heat --- efficiency is only 30%

Production

• amount of an energy source extracted from reserves during a particular time

renewable energy

• derived from sources that are not depleted when they are used (sunlight and wind) or that can be replenished in a short period of time (such as fuelwood)

Global energy needs

• 80% fossil fuels
• 4% nuclear energy
• 7% traditional renewable energy (fuelwood, charcoal; esp. poor countries)
• <10% modern renewable energy (hydropower, solar, biofuels, wind, geothermal energy)

proved reserves

• quantities of an energy resource that could be recovered from known deposits using current technology at current prices

reserves-to-production ratio (R/P ratio)

• proved reserves for a given fuel divided by a particular year's level of production or use
• provides an estimate of how many years a fuel will last if the level of production remains constant and no additional reserves are discovered

Energy returned on investment (EROI)

• useful energy provided from an energy resource divided by the amount of energy it took to produce it
• Measure of sustainability of energy sources
• higher ratios mean that we receive more energy from each unit of energy that we invest in

Resources

• include all deposits on Earth (those that are known and those that have yet to be discovered; those that are economical and those that aren't economical yet)

Reserves

• a known quantity of resource that can be extracted economically by today's standards

Advantages of fossil fuels

• Global availability
• Efficient source of energy
• Low cost
• Fossil fuels are more cost effective than nuclear or renewable energy sources
• Existing infrastructure
• tankers/pipelines/refineries
• switching to another source would be costly
• Power plants can be set up anywhere

Dangers of Underground Mining

-Tunnels can collapse.
-Natural gas explosions
-Water seeping into mine shafts dissolves toxic minerals and contaminates groundwater.
-Fires in mines which burn for years

mine tailings

rock and debris from mining operations; often contain high concentrations of pollutants

acid mine drainage

• when rainfall infiltrates into coal waste piles and reacts with pyrite (iron-sulfide mineral) in the presence of free oxygen to produce acidic, metal-rich contaminated water

Geological conditions necessary for oil/gas reservoir formation

1) Shallow sea with large concentration of aquatic organisms that died, sank, were covered by sediments, and transformed into oil by T and P
2) Oil must migrate upward into porous rock reservoir
3) Rock must be covered by impermeable rock layer (cap rock) that traps the oil

secondary oil recovery

injection of water to extract another 10-20% of the oil reservoir after the primary recovery stage

tertiary oil recovery

• flow of additional oil is stimulated by injecting Co2 steam or hot water into reservoirs
• Fracking
• Additional 10-20%

hydraulic fracking

• used to extract oil or natural gas from shale deposits several thousand feet beneath the surface
• Well shafts are drilled horizontally into the shale deposits and injected with a mixture of liquids and sand (high-pressure liquids)
• Rocks fracture, sand holds fractures open

Environmental issues of hydraulic fracking

• Water availability (3.5-26 million liters; 1-7 million gallons of water per well)
• spills of chemicals at the surface
• impacts of sand mining for use in the hydraulic fracturing process
• surface water quality degradation from waste fluid disposal
• Noise and air pollution
• groundwater quality degradation
• induced seismicity from the injection of waste fluids into deep disposal wells

liquefied natural gas (LNG)

Natural gas converted to liquid form by cooling it at a very low temperature (for long-distance transport)

Traditional renewable energy sources

wood, charcoal; developing countries; major source of pollution

Modern (clean) renewable resources

hydropower, solar, wind power, biomass, ocean energy, geothermal energy

Challenges to widespread use of renewable energy

• New technologies: many uncertainties and risks --- scarce investment capital --- companies pay high interest for investments funds --- development expensive
• Economies of scale: small scale = production cost high = demand low (solar panels)
• Externalized costs: price we pay for gas/electricity does not include all costs related to production and use (government subsidies --- people have no incentive to conserve energy; medial costs associated with health problems)
• Limited consumer knowledge and understanding: energy usage numbers of cars, appliances; no influence on electricity sources of power company, decisions made by contractors not owners)

Passive solar technologies

• use the energy of sunlight without relying on electrical or mechanical devices such as pumps or fans (e.g., orientation of buildings, building materials that absorb sunlight, modern energy-efficient buildings)

photovoltaic (PV) cells

a technology that converts solar energy directly into electricity

biomass energy

energy contained in firewood and other plant matter
• combustion of firewood, charcoal, agricultural/forestry waste (sawmills burn wood scraps and sawdust to dry lumber, papermills fire generators)
• conversion of crops (sugarcane, corn) to liquid fuels (ethanol)

wind farms

clusters of wind turbines in areas with strongest and most regular winds

Advantages of wind power

• No fuel, mining, drilling, pipelines, waste, water, pollution
• Economical
• domestic source
• No GHG emissions
• Less disruption by natural disasters and terrorist attacks

Disadvantages of wind power

• Risk of bird and bat mortality
• Aesthetics (diminish scenic views)
• Intermittent
• Remote locations