ENVIRON 102 Chapter Notes - Chapter 15: Open-Pit Mining, Spent Nuclear Fuel, Internal Combustion Engine
10 May 2018
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Chapter 15 Nonrenewable Energy and Electricity (all)
15.1 Energy Production and Consumption
Energy Sources: For more than 100 years, most of our energy needs have been met by nonrenewable
fossil fuels
Primary energy: energy contained in natural resources
o Ex: coal, oil, sunlight, wind, and uranium
Energy conversions: processes that transform primary energy into secondary energy and so on
o Ex: electricity, kinetic energy of an automobile
End use: final application of energy such as running an appliance or driving a car
Energy conversion efficiency: % of primary source energy captured in a secondary form of energy
o Ex: when coal is burned to generate electricity about 70% of energy is lost as heat
Energy end-use efficiency: product of the efficiencies of all the energy conversions from the
primary source to the end use
o Ex: Coal transformed into energy powering incandescent lightbulb – 1.2%
Nonrenewable energy: derived from sources that exist in limited quantities
o Three main types of fossil fuels: crude oil, coal, and natural gas (and nuclear energy)
o Fossil fuels – formed from organisms’ remains over millions of years via geologic processes
Renewable energy: derived from sources that are not depleted when they are used
o Ex: sunlight and wind
Shifts in the sources of energy reliance for humans
o Prehistoric – solar, chemical from food, and fuelwood
o Development of agriculture – energy from domestic animals, flowing water, wind, and
fossil fuels
o 1750 Industrial Revolution – very large dependence on fossil fuels
o Today – still a very large dependence on fossil fuels (~80% of global energy needs)
End Use: Primary energy sources vary in importance, depending on the country and specific end use
End-use sectors: transportation, industry, residential/commercial, and electricity
Future Energy Portfolios: Future patterns of energy use will depend on the size of the reserves and rate of
extraction, market prices, and environmental impacts
Concern over long-term viability of fossil fuels
Proven reserves of nonrenewable energy sources – quantities of fuel that can be recovered from
known deposits using current technology at current prices
Reserves-to-production ratio (R/P) – proven reserves figure for a given fuel divided by a
particular year’s level of production or use
o How many years a fuel will last given no additional reserves are discovered and extraction
is constant
o Ex: oil will be exhausted in 40 years, natural gas is about 67, and coal is around 120
Energy return on investment (EROI) – measure of the useful energy produced from an oil, well,
natural gas field, or coal mine divided by the amount of energy it took to obtain it
o Oil that can be easily extracted – higher EROI
o The more oil pumped from the ground, the lower the EROI because it gets harder to pump
the oil
Burning of fossil fuels – contributor to air pollution and climate change
Environmental constraints are driving a need for alternative sources of energy
15.2 Electric Power – Generation, Distribution, and Use
Generating Electricity: Most of the electricity we use is generated by the kinetic energy that comes from
primary energy sources
Electricity generated in power plants
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o Primary energy sources such as coal and natural gas heat water and create pressurized
steam
o Steam turns a turbine which powers a electrical generator (or dynamo)
OR water and wind may move the turbine, driving the generator
Spinning magnets in generator create an electromagnetic field, which provides the voltage for an
electric current to flow
Power plants operate at low voltage
Transformers reduce the amperage (current) and increase the voltage – makes flow of electricity
over long distances more efficient
o Transformers near home reduce the voltage delivered to home
Electric power grid: multiple power plants that supply electricity to a network of transmission
lines and transformers
o May draw from a lot of primary energy sources
o Components create resistance to flow of electricity
▪ Resistance turns some electricity into heat (about 7-10% loss)
o If demand > production = brownouts or blackouts
Base load: minimum amount of electricity that a utility must provide to meet consumer needs
Peak load: maximum amount of electricity demanded by consumers
Cost increases as demand increases from base load to peak load
Electric power grids distribute energy from large, centralized facilities that derive power from
nonrenewable resources
Facilities with renewable resources generate less power and are more scattered
Batteries use chemical energy to produce electrical potential
SmartGridCity – project aimed at improving communication between consumers and amount of
electricity they use
Environmental Impacts: Transmission of electricity has uncertain health effects
Debate over possible health effects of electromagnetic fields created from electric currents
o Evidence that children who live near power lines have higher rates of leukemia
Transformers are immersed in coolants which contain PCBs
o PCBs have toxic effects on wildlife and humans and are resistant to decomposition
o Use of PDBs is banned
Discarded batteries – source of mercury and lead pollution
15.3 Coal
Most abundant of fossil fuels
Sources and Amounts: Coal was formed from plants that lived in swamps hundreds of millions of years
ago
Plant material fall into swamps, covered by sediment and water
Turns into peat (organic material that is broken down anaerobically into a wet, partially
decomposed mixture material)
Accumulation of thick layers of sediment over peat
High temperature and pressure caused by weight of sediments forces water out of peat and packs
carbon compounds closer together which forms coal!
Coal seams: layers of sediment that contain coal
Carbon and energy content of coal dependent on age and extent of underground heat and pressure
Lignite: type of coal generally associated with younger deposits not subjected to much heat and
pressure
o Relatively soft and contains some moisture, 25-35% carbon
Sub-bituminous coal: 35-45% carbon, higher energy content
Bituminous coal: formed under higher heat and pressure, 45-86% carbon, (aka hard coal)
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Anthracite coal: 86-97% carbon, less common, found in greater depths, (aka hard coal)
Hard coal – higher energy content and less polluting chemicals
Enough coal to last about another 120 years
Most coal reserves found in US, Russia, China, and India
Coal Extraction and Processing: Shaft mines and strip mines provide access to coal seams
Coal extraction via underground and surface mining
Surface mining (aka strip mining) extracts coal from deposits less than 200 ft underground
o Removal of topsoil and layers of rock (overburden), exposing coal seams
o Mountaintop removal, overburden is dumped into valleys (refer to ppt)
After coal is extracted, it is cleansed to remove impurities
In US, most of coal production generate electricity
Energy production with coal
o Coal burned to produce heat
o Heat captured in a boiler and used to produce pressurized steam
o Steam turns a turbine which powers an electrical generator
o After steam passes through turbine, it condenses into water and the remaining heat
dissipates
Exhaust from burning coal passes through scrubbers
o Scrubbers remove particulates and pollutant gases (such as nitric and sulfuric oxides) from
exhaust
o Exhaust is then released into atmosphere
o Material left behind is fly ash
Older power plants worked at 25% efficiency while modern ones are 40% efficiency
Environmental Impacts: Coal mining and coal combustion present significant environmental challenges
Underground coal mining is dangerous (flooding, dust, gas explosions, and cave-ins)
Mine tailings: rock and debris from mining operations
o Contain high concentrations of sulfide
o Sulfides + oxygen = sulfuric acid (which harms fish in nearby streams)
Surface mining destroys the ecosystems above coal seams
Return of overburden and topsoil plus efforts to revegetate (realistically, not that effective)
Exhaust and fly ash contain toxic chemicals
o Fine particulate soot = respiratory distress
o Coal contains mercury which is released into atmosphere and affects nearby communities
▪ Mercury accumulates in organisms’ tissues health problems (neurological
disorders)
o Nitric and sulfuric oxide cause nitric and sulfuric acid acid deposition
Efficiency of scrubbers – can remove most of sulfuric oxides but less than majority of mercury
Carbon emissions – climate change
2030 – coal consumption predicted to double
Carbon capture and storage (CCS) technologies – capturing carbon dioxide in underground
geologic formations
o Critics states that CCS adds cost to coal-produced energy
o Uncertainty about whether there would be eventual leakage of carbon dioxide into the
atmosphere
15.4 Oil
First commercial oil well – 1859 Pennsylvania
35% of global energy use
Sources and Amounts: Oil formed under specific geologic conditions that were common in only a few
places.
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Document Summary
Energy sources: for more than 100 years, most of our energy needs have been met by nonrenewable fossil fuels. Primary energy: energy contained in natural resources: ex: coal, oil, sunlight, wind, and uranium. Energy conversions: processes that transform primary energy into secondary energy and so on: ex: electricity, kinetic energy of an automobile. End use: final application of energy such as running an appliance or driving a car. Energy conversion efficiency: % of primary source energy captured in a secondary form of energy: ex: when coal is burned to generate electricity about 70% of energy is lost as heat. Energy end-use efficiency: product of the efficiencies of all the energy conversions from the primary source to the end use. Nonrenewable energy: derived from sources that exist in limited quantities: three main types of fossil fuels: crude oil, coal, and natural gas (and nuclear energy, ex: sunlight and wind. Shifts in the sources of energy reliance for humans.
