Topics to be addressed:
• Energy sources that fuel
our civilization
• History of energy use
• Patterns of energy
production and
consumption
• Crude oil, coal, natural
gas, and nuclear energy
• Environmental, political,
and social impacts of
fossil fuel use
Energy sources used today
• Growth in coal has slowed, but oil and gas are still rising.
Figure 17.5
Canadians are the highest
per-capita energy users
on planet Earth !
Figure 17.3
•Hydrocarbons
•Found in sedimentary rock
•Remains of prehistoric animals, forests
and sea floor life (FOSSIL FUELS)
•Toxic to wildlife (spills)
•Climate change
•Air pollution and acid rain
Canadian production
about 3 million barrels/day
(ie., now red on map!)
Fossil fuels
• These are fossils in the sense that they are made of
remnant decayed material from ancient organisms.
• Compressed tissues of plants (and some animals)
from 100–500 million years ago store chemical
energy from photosynthesis.
• This greatly concentrated energy is released when we
burn coal, oil, or gas.
Fossil Fuels
• Anaerobic (without oxygen) decomposition is
required for fossil fuel formation.
(Aerobic = decay in presence of oxygen)
Anaerobic environments exist at the bottom of the
ocean, in deep lakes, and in swamp sediments.
FOSSIL FUEL FORMATION
•
Plants and animals die
•
Organic material
settles in anaerobic site
and is partly
decomposed
•
Organic material is
buried
•
Heat and pressure alter
chemical bonds
•
Coal, gas, oil formed
Figure 17.6
• Coal: Compressed under high pressure to form
dense carbon structures.
• Natural gas: Primarily methane, CH4, is
produced:
– By bacteria near surface
– By heat and pressure deep below ground
• Crude oil: Sludgelike mix of hundreds of types of
hydrocarbon molecules. Forms at temperatures
and pressures found 1.5–3 kilometers below
ground.
The ANWR National Wildlife Reserve: Contentious US Issue
Alaska’s North Slope
Figure 17.1
Distribution of Conventional
Fossil Fuel Reserves
Figure 17.8
Distribution of Conventional
Fossil Fuel Reserves
• Saudi Arabia has the
most oil.
• Russia has the most
natural gas.
• The U.S. has the most
coal.
Oil: Drilling
• Liquid oil exists in pores in rock deep
underground.
• We must drill into rock and extract oil by
using a pressure differential.
• The more oil is extracted, the harder it is to
extract:
Refining Crude Oil
• Crude oil from the ground is a messy mix of hundreds of
hydrocarbons.
• It is put through a refining process to segregate different
components.
–Small-chain hydrocarbons boil at cooler temperatures in a
distillation column, isolating lighter weight oils (e.g., butane).
–Long-chain hydrocarbons boil at hot temperatures, isolating
heavier oils (e.g., lubricating oils).
Refining crude oil
Petroleum Products
• Refined components of crude oil are used to
manufacture many of the material goods we use
every day.
• Petroleum products include:
• Helmet, water bottle,
sunglasses, clothing,
sunscreen, gear and
chain grease
Figure 17.11
Oil Conservation
• Although oil is a limited resource, prices have remained
low enough that few people feel the need to conserve
• Conservation measures taken in the 1970s resulting from
fears of oil shortages were mostly abandoned, but recent
price increases may cause history to repeat itself
• As oil supplies dwindle, conservation will again become
popular.
• Geologist M. King Hubbert predicted U.S. oil production
would peak around 1970 and then decline.
• He was only a few years off.
Figure 17.15a
Depletion of Oil Reserves
• World oil reserves are a finite resource as well.
• Some observers predict they have peaked.
Figure 17.15b
Vehicle Fuel Efficiency
• Automobile fuel efficiency rose after the oil shocks of the
1970s, but has stagnated since then.
Figure 17.13
•Clay, sand, water and bitumen
•Black oil rich in sulphur
•Oil sands must be heated and treated
with steam to separate bitumen
•Energy intensive
•Sulphur dioxide emissions
•Huge waste disposal ponds
•Habitat fragmentation
•Greenhouse gas emissions
Photos: Syncrude
•Most CO2 and
air pollution per
unit energy
•Sydney tar ponds
- the most
contaminated site
in Canada
* New technology
may present cleaner
coal burning options
(eg. improved boiler
efficiency)
Illustration: Brooks Johnson,
Ontario Clean Air Alliance
• Several types of coal exist, depending on the amount
of heat and pressure that overlying sediments have
Figure 17.16
exerted.
• Coal is mined either
underground, in
subsurface mining,
or from the surface, in
strip mining.
Figure 17.17
•Gaseous hydrocarbon mixture
Primarily methane – CH4
Also C3H8 and C4H10
•Now 45% of Canada’s energy production
•Much cleaner and more efficient
Problems: potent greenhouse gas,
wildlife disruption, flaring & H2S
Natural Gas: History
• Seeps known for 2,000+ years
• Used for street lighting in the 1800s
• Became commonly used after WWII
once pipeline technology became
safer
Natural Gas Formation
• Forms in two ways:
Biogenic gas = formed at shallow depths by anaerobic
decomposition of organic matter by bacteria
Thermogenic gas = formed at deep depths as
geothermal heating separates hydrocarbons from
organic material
(Formed directly OR from crude oil altered by heating. Thus gas deposits often
occur with oil deposits.)
Gas Extraction
• Initially, gas comes out on its own from natural pressure.
• Later, it must be pumped out.
Horsehead
pump to
extract
natural gas
Figure 17.18
15% of Canada’s electricity
>50% of Ontario’s electricity
Nuclear Power
• 6.8% of world’s primary energy supply
• 16.9% of world’s electricity production
• Grew 15-fold since 1970
• Has stagnated due to safety concerns and economics
Nuclear energy
• Two ways to produce nuclear energy:
•
Fission: used for power
•
Fusion: not yet used commercially
Nuclear Energy
• Comes from the radioactive
element uranium
• The nuclear fuel cycle
enriches forms of uranium
to make it into usable fuel.
• Waste fuel is radioactive and
must be specially disposed
of.
Figure 17.24
Nuclear Energy: Fission
• Fission = energy is released by splitting apart uranium
nuclei by bombarding them with neutrons.
• This is the process used in nuclear reactors and weapons.
Figure 17.25a
Nuclear Energy: Fission
• Note that several neutrons
are produced from each
reaction with one neutron.
• This means the reaction
could be a runaway
reaction, or explosion.
• In a commercial reactor, the reaction must be controlled.
• Metal rods are used to absorb the extra neutrons. Engineers
move these control rods to regulate the reaction.
Figure 17.25a
Nuclear Reactor
• In a reactor, fission boils steam to turn a turbine and
generate electricity
Figure 17.26
Nuclear Troubles
• Although nuclear power is clean, lacking the
pollutants of fossil fuels, it has faltered, due to:
– • Cost overruns
– • Public fears of catastrophic accidents
– Three Mile Island, 1979
– Chernobyl, 1986
• 450 nuclear plants remain operating today in the
world; 100 have closed.
•No greenhouse gas emissions/air
pollution (except mining)
•Minimal land disturbance
•High energy output with minimal
environmental impact
Problems:
•Storage of nuclear waste
(DGD in Canadian shield proposed)
•Expensive
•Public trust / meltdown risk
(older systems)
Renewable Energy Sources
• Biomass & Biogas: from combustion of organic material
• Hydropower: from water flowing through dams
• Solar: from the sun’s rays
• Wind: from the wind
• Geothermal: from heat and heated water beneath the
ground
• Ocean sources: from the tides and from waves
• Hydrogen: fuel and fuel cells that store renewable energy
in usable form
GLOBAL ENERGY SUPPLY
SOURCES OF ELECTRICITY
Renewable Sources: Outlook
• The outlook for renewable sources is good.
Growth should continue.
But will governments raise subsidies to the level
offered to fossil fuels?
Will research and development proceed fast
enough?
Will consumers choose alternative energy sources
Turbine generator inside dam
Hydro Power
•12% of Canada’s energy
•No air pollution
•Downstream irrigation regulation
Pros and cons of hydroelectric
power
PROS
CONS
• Renewable as long as
water is not overdrawn
from river system
• Dams cause numerous
disruptive ecological
effects to riparian
environments
• Clean: no greenhouse
gas emissions
• Dams bring a mix of
impacts for people
Wind Power
• Takes kinetic energy of wind and converts it to electrical
energy
• Fastest growing power source today
• Technology = wind turbines, machines with turning
blades that convert energy of motion into electrical
energy by spinning a generator
Windmills have been used for centuries.
First wind turbine for electricity: late 1800s
Annual average wind power
Wind power
Figure 18.12a
Wind Power: Wind Turbines
• Wind spins the blades, which turn the gearbox, which
turns the generator to produce electricity.
Figure 18.9
Wind Power: Wind Turbines
• Turbines are often
located in groups
(“wind farms”) at
sites with
exceptionally good
wind conditions.
Wind Power
• Most wind power so far is concentrated in a few nations.
Figure 18.11
Wind Power
• By surveying with
anemometers that
measure wind
speed, people can
determine sites
that will be best
for wind power
production.
From The Science behind the Stories
•Near zero environmental impact
•Potential exists to reverse current
level of impact from other sources
•Each turbine powers at least 250
Alberta homes!
•It’s windy here!
Pros and Cons of Wind Power
PROS
CONS
• Renewable, as long as wind
blows
• Not everywhere is
windy enough
• No emissions after equipment
made, installed
• Windy sites can be far
from population centers
• Can allow local decentralized
control over power, and local
profit from electricity sales
• Blades kill birds, bats
• Costs low after initial
investment; costs dropping
• High start-up costs
Biomass
Organic substances produced by recent photosynthesis
(unlike fossil fuels, products of ancient photosynthesis)
More than 1 billion people
burn fuelwood as their
principal power
source for cooking,
heating, etc.
Biomass
•Wood, agricultural wastes, garbage
15% of world’s energy
6% of Canada’s energy
Mainly in developing nations
•Less emission of greenhouse gases if
forest replacement exceeds removal (wood)
•Biofuels for cars (ethanol - Brazil)
Problems: land clearing and associated
problems (wood)
Pros and Cons of Biomass
PROS:
CONS:
• Renewable, as long as
forests aren’t depleted
• Does not always reduce
CO2 emission as much as
other renewables
• Usually inexpensive
• Some waste can be used
for energy
• Capturing methane
reduces that greenhouse
gas
• Cutting trees for fuelwood
can lead to deforestation
• Growing crops for fuel
(e.g., corn for ethanol) is
highly inefficient
Biogas Production from Manure
• Electricity Generation
• Gas for cooking
• Heat
• Utilized in Southern Alberta
(eg. Iron Creek Hutterite Colony)
Photos: Rokai Pig Farm,
Kaunas, Lithuania
http://www.folkecenter.dk/en/rokai/rokai.html
INLET
OUTLET
Difficulties
•Temperature optima maintenance
•Acidity: pH sensitive anaerobic bacteria
(lime required)
•NH3 toxicity (control input rate)
•CH4 won’t liquefy – difficult to store
(must use or burn)
Geothermal Energy
• Radioactive decay of elements deep in Earth’s core
creates heat that rises toward the surface.
• This heats magma of volcanoes, and also underground
water.
• Sometimes water spurts through to the surface in geysers.
• Geothermal power plants use the energy of naturally
heated water to generate electricity.
Geothermal Energy
• Underground
heat warms
water, and
steam turns
turbines and
generators.
• Condensed
steam is
reinjected into
the aquifer to
keep up
pressure.
Figure 18.13a
Geothermal Energy
• Iceland uses
geothermal
energy to heat
water for 86%
of its homes.
• Heat pumps
using surface
heat can also
be very
efficient.
Geothermal plant in Iceland
Figure 18.13b
Pros and Cons of Geothermal Power
PROS
CONS
• Renewable, as long as
water is heated naturally
• Heated water may give out
after a while—hotspot
moves or aquifer pressure
drops
• Much lower greenhouse
gas emissions than fossil
fuels
• Can be inexpensive in
areas where geothermal
heating naturally occurs
• Salts in water can corrode
equipment, shorten lifespan
• Limited to geographic areas
where geothermal heating
naturally occurs
Ocean Energy Sources
• Three sources from oceans:
Tidal power: The twice-daily flow of tides (rising and
falling of seas due to the moon’s gravitational pull)
creates energy of motion that can be converted to
electricity.
Wave power: Motion of waves at ocean shores creates
energy of motion that can be converted to electricity.
Tidal Energy
• The LaRance power station in France is the world’s
largest tidal generating station. Its turbines spin with
both incoming and outgoing tides.
Figure 18.14b
Wave Energy •
There are
several designs
for wave energy
stations.
• In this one, air is
compressed in a
chamber with
each incoming
wave, driving a
turbine to spin a
generator.
Figure 18.15
Pros and Cons of Ocean Power
PROS
CONS
• Renewable, as long as
oceans behave as they
always have
• Development could take up
large portions of coastline
valuable for other uses
• No greenhouse gas
emissions
• Could interfere with
ecology of estuaries and
intertidal shorelines
Source: DOE, USA
Solar Energy
• Use of energy
from the Sun
• Huge potential: Each day Earth
receives enough sunlight to power
human consumption for 27 years, if
we could somehow capture it all.
Solar energy
• Passive solar = designs buildings to maximize capture
of sunlight in winter, but keep buildings cool in summer
through window placement, absorbent materials…
• Active solar = uses technological devices to focus,
move, or store solar energy
–Solar panels: dark heat-absorbing metal plates in glasscovered boxes, often mounted on roofs
Solar energy: Active solar
• Portable solar cookers focus sun’s rays onto a small
area—here, boiling water in Nepal. These are becoming
popular throughout the developing world.
Figure 18.6
• Numerous mirrors focus sunlight on a receiver atop a
“power tower” in the California desert. This facility was
the first to generate much solar power commercially.
Application:
Steel Production
Facility
Source: www.technologystudent.com/energy1/solar4.htm
Solar Energy: Active Solar
• Gaviotas,
Colombia, uses
solar panels in
homes and
businesses for
heating, cooling,
and water
purification
(This photo is from
Bogotá)
Figure 18.5
Solar Energy: PV Cells
• Photovoltaic cells (PV cells) convert solar energy
directly into electrical energy by making use of the
photoelectric effect:
• Sunlight strikes one of a pair of negatively-charged metal
plates
• Electrons migrate to opposing plates, and electric current
is produced.
• In PV cells, light strikes negatively charged phosphorusenriched silicon, and electrons migrate downward
through silicon to positively charged boron-enriched
silicon.
Solar Energy: PV Cells
• Electrons move from the phosphorus side of the silicon
plate to the boron side, creating electric current. PV cells
are arranged in modules, panels, and arrays.
Figure 18.8
Solar Power
• Is little used, but fast growing
•
Currently only 0.04% of primary energy supply
in the U.S.
•
Growing at 33% per year
Cheaper technologies are taking off in developing
countries.
• More expensive technologies are growing more slowly in
developed countries.
Pros and Cons of Solar Power
• PROS:
• CONS:
• Renewable, as long as sun
keeps on shining
• Not everywhere is
sunny enough
• Sun’s energy abundant, if
technology can capture it
• Up-front investment
cost is high; takes years
to pay for itself
• Allows for local decentralized
control over power
• No greenhouse gas emissions
(although some are created in
manufacture of technology)
Photo: WIRED
Hydrogen
• Hydrogen = simplest and most abundant element in
universe
• Could potentially serve as basis for clean, safe, efficient
energy system
• How it would work:
– Electricity generated from intermittent renewable sources like
wind or solar can be used to produce hydrogen.
– Fuel cells can then use hydrogen to produce electrical energy
for power.
Production of Hydrogen Fuel
• Hydrogen gas (H2) does not exist freely on Earth.
• We need to make it.
• Electrolysis is the cleanest way:
• Split water into hydrogen and oxygen:
2 H2O  2 H2 + O2
• This can potentially be very clean, releasing no
greenhouse gas emissions.
Production of Hydrogen Fuel
• However, cleanliness of hydrogen production depends on
source of electricity for electrolysis!
• If the source of electricity needed for electrolysis is not
clean (e.g., from coal), then greenhouse emissions will
still occur.
• Besides electrolysis, hydrogen can also be produced from
organic molecules like fossil fuels. This entails
greenhouse emissions.
• H = 75% of the universe’s mass !
• Combustion engines can be fuelled by hydrogen (Ballard
Power – Canadian company and leader in this field)
Fuel Cells
• In a fuel cell, hydrogen gas is used to produce electricity.
• The reaction is simply the opposite of electrolysis:
2 H2 + O2  2 H2O
How it works:
• Hydrogen molecules are stripped of electrons.
• H+ ions move through a membrane.
• Electrons complete a circuit, creating electricity.
Fuel cells
Figure 18.16
O2 + 4H+ + 4e- => 2H2O
2H2 => 4H+ + 4e
NET REACTION: 2H2 + O2 => 2H2O
Pros and Cons of Hydrogen Power
• PROS:
• CONS:
• We will never run out of
hydrogen
• Depending on way
hydrogen is produced, it
may not be
environmentally clean
• Can be clean and non toxic,
with no greenhouse gas
emissions
• Fuel cells potentially
convenient, safe, and
efficient