unit 9 energy chapters 15 and 16. worldwide energy use nonrenewable energy fossil fuels coal oil...
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Unit 9 Energy
Chapters 15 and 16
Worldwide Energy Use
Nonrenewable Energy Fossil Fuels
Coal Oil Natural Gas
Nuclear Fuels Radioactive Materials
Renewable Energy Can be replaced during a human lifespan
Worldwide Energy Use cont. Worldwide 20 % of population live in MDCs and are
responsible for 70% of world’s energy use Energy Use is not evenly distributed throughout
the world US consumption = 355 GJ per person per year in
2007 which is 5 times greater than the world average
Countries use energy at different rates What resources are available What resources are affordable
Countries rely on different energy resources
Worldwide Energy Use cont. As countries develop - energy use changes MDCs/Urban areas
Commercial Energy sources Primarily use fossil fuels Either burn them directly or burn them to provide
electricity LDCs/Rural areas
Subsistence Energy Sources Wood, charcoal, animal waste Use more human and animal energy
Units of Energy
Joule (J) – the basic unit of energy Gigajoule (GJ)
1 billion joules (1 x 109) Equivalent to 30 gallons of gasoline
Exajoule (EJ) 1 billion gigajoules
Quad Only used by the US Government 1 quadrillion Btu (1 x 1015) 1 quad = 1.055 EJ
World vs. US Energy Consumption
Net Energy
The total amount of useful energy available from an energy resource minus the energy needed to make it available to consumers.
Energy Waste
Second law of thermodynamics About 40% of all commercial energy is wasted
due to this law Efficiency
Another 40% is wasted through inefficient use of Energy
Internal combustion engines Incandescent light bulbs Lack of insulation in buildings Single paned windows
Nonrenewable Energy - Oil Supplies about 1/3 of the world’s commercial
energy use Supplies about 40% of US energy use OPEC
Organization of Petroleum Exporting Countries Algeria, Angola, Ecuador, Indonesia, Iran, Iraq,
Kuwait, Libya, Nigeria, Quatar, Saudi Arabia, the United Arab Emirates, and Venezuela
Control about 60% of the world’s proven oil reserves
Use is exceeding new oil field discoveries
Oil Supply and Use 3 largest consumers: US, China, Japan Largest producers: Saudi Arabia, Russia, US, Iran,
China, Canada, Mexico Proven reserves
Identified deposits that can be extracted profitably Geologists estimate that 80% will be used up by 2100
Unproven reserves Probable – greater than 50% chance of recovery Possible - less than 40% chance of recovery
Peak Oil The point in time when we reach the maximum overall
rate of conventional crude oil production for the whole world
Oil Exploration
Bakken Oil Formation ANWR Alaska’s North Slope/Prudhoe Bay Texas
Anadarko Basin
Oil Classifications
Petroleum/Crude Oil Mixture of hydrocarbons, water, and sulfur Conventional oil aka light or sweet crude Heavy oil
Thick, comes from wells that have had the light oil removed or from tar sands and oil shale rock
Petrochemicals Products of crude oil distillation
Oil Refineries
150 in the US Some produce as much as 80 million liters
per day Oil production is measured in barrels of oil 1 barrel equals 160 liters or 42 gallons
Petroleum
Pros As a liquid – it is easy to
transport and use Energy-dense Cleaner burning than coal
Cons Releases CO2 (15% less
than coal) Contains sulfur and
traces of Hg, Pb, As Extraction and processing
have detrimental effects on land
Oil spills Habitat destruction
Oil vs. Heavy Oil
Heavy OilTar Sands
Mixture of clay, sand, water, and bitumen (sticky, tarlike oil with high S content)
Harmful impacts on land, air, water, wildlife due to strip mining
Is converted to low-sulfur synthetic, heavy crude oil suitable for refining by large inputs of fossil fuels
Oil Shale
Oily rocks made of a solid combustible mixture of hydrocarbons called kerogen
Extracted from crushed oil shale after heating, the distillate is called shale oil
Contains sulfur & nitrogen which must be removed
High water use for processing
Natural Gas Exists two ways
with oil/petroleum deposits Independent deposits
80 – 95% methane, and a mixture of ethane, propane, and butane
Lighter than oil, so lays above the oil in petroleum deposits
In the past, only extracted in association with oil, now natural gas is a sought after resource on its own
Natural Gas cont.
Uses Electricity production Industrial processes Manufacture nitrogen fertilizer Cooking, heating, clothes dryers, hot water
heaters
Natural Gas cont.
Liquefied Petroleum Gas Similar to natural gas, but
in liquid form Slightly less energy
dense Can be transported by
truck, train, or stored at point of use in tanks
Gas grills and other “propane” tanks
Liquefied Natural Gas Can be used as a fuel for
vehicles, must be transported by pipeline, limiting the usefulness of this resource
Coal Bed Methane found in coal beds near
the earth’s surface
Natural Gas cont.
Pros Contains fewer impurities
than coal and oil Emits no SO2 or
particulates
Cons Releases CO2 (but 40 %
less than coal) Unburned natural gas
contains methane – a greenhouse gas
Extraction and processing are environmentally harmful
Fracking Hydraulic fracturing Drilling with water, sand, and proprietary
chemicals whose names and effects do not have to be disclosed to the public
Large quantities of water are used and become contaminated during this process
Groundwater may be contaminated by this process
National Geographic Fracking The Fracking Song
Coal Fuel most commonly used for the generation
of electricity in the US Solid fuel formed primarily from the remains
of trees, ferns, and other plant material 4 types
Lignite, sub-bituminous, bituminous, anthracite Largest coal reserves are found in: US,
Russia, China, India Greatest coal producers: China, US, India,
Australia
Coal cont.
Pros Plentiful Energy dense Relatively easy to mine Easy to handle and
needs little refining Can be transported easily Inexpensive
Cons Contains sulfur which is
released to the atmosphere as SOx, leading to acid rain
Trace metals : Hg, Pb, As Releases particulates into
the air when burned Releases CO2 - greatest
amount of all fossil fuel Coal Ash
Coal Ash
Contains As, Cd, Cr, Pb, Hg, Ra 2 types of coal ash
Fly ash Created from the process to removal metals and sulfur
from power plant emissions Microscopic
Bottom ash Comes directly from burning the coal Stored in coal ash ponds Coal Ash Pond Spill- Knoxville, Tennessee - 2008
Coal Ash
Fly Ash (20,000x magnification) Bottom Ash - Raw
Synthetic Natural Gas Can be created from coal through
Coal gasification Coal liquefaction
Advantages Large potential supply Can be used as vehicle fuel Less air pollution than coal
Disadvantages Low net energy yield Uses 50% more coal = impacts on land, water, air Higher CO2 emissions than coal
Fission vs. Fusion Fission
Nuclear reaction in which a neutron strikes a relatively large atomic nucleus, which then splits into two or more parts
More neutrons are released as well as energy in the form of heat which leads to a chain reaction of nuclear fission that produces an immense amount of heat energy which is used to produce steam to turn a turbine to produce electricity
Fission vs. Fusion Fusion
The reaction that powers the Sun, occurs when lighter nuclei are forced together to produce heavier nuclei
This process generates a large amount of heat Fusing 2 Hydrogen atoms into Helium Current methods focus on suspending superhot
material in a magnetic field, but the amount of energy required is greater than the energy released
Not economically feasible at this time
Nuclear power plant
Uranium-235 (mined) is the fuel source undergoing radioactive decay
Radioactive decay causes fission to occur Containment Structure/shell holds
Fuel rods – the nuclear fuel (in pellet form) is encased in cylindrical tubes
Control Rods – cylindrical devices that are inserted between the fuel rods to absorb excess neutrons, thus slowing or stopping the fission reaction
Nuclear Accidents Level 5 accidents
March 28, 1978 3 mile Island – Pennsylvania Operator error
March 11, 2011 Fukushima - Japan Earthquake
Level 7 accidents April 26, 1986
Chernobyl – Russia Operator error
Radioactive Waste Must be stored in special, highly secure
locations High level waste
Spent fuel rods Low level waste
Contaminated clothing, tools, rags and other items used in routine plant maintenance
Uranium mine tailings Residue left after uranium ore is mined and
enriched
Radioactive Waste Disposal
Disposal of all forms of radioactive waste are regulated by the government
High level waste disposal Nuclear fuel rods become “spent” – meaning
they do not have enough radioactivity to generate electricity, but they are still radioactive and therefore a threat to human health
Uranium has a half-life of 704 million years and spent fuel rods remain a threat to human health for at LEAST 10 half lives.
Radioactive Waste Disposal cont. High level waste cont.
Spent fuel rods are stored in pools of water at least 20 feet deep.
Water acts as a shield from radiation and keeps the rods cool
Eventually the rods can be moved to dry storage in lead lined containers
Can NOT be incinerated, destroyed with chemicals, shot into space, dumped on the ocean floor, or buried in an ocean trench b/c of the potential for huge releases of radioactivity into our atmosphere or water
Radioactive Waste Disposal cont.
Current solution is to store the waste indefinitely
Storage must be planned carefully to ensure that the waste will not leach into the groundwater
Needs to be in an area that is sparsely populated and secure from terrorist attacks
Long-term disposal facility Yucca Mountain (1978)
Radiation
There are a variety of units for radiation Becquerel – measures the rate at which a
sample of radioactive material decays 1 Bq = to the decay of one atom per second
Curie - is 37 decays per second
If a material has a radioactivity level of 100 curies and has a half-life of 50 years, the radioactivity level in 200 years will be?
Calculating half-lives
Strontium-90 is a radioactive waste product from nuclear reactors. It has a half-life of 29 years. How many years will it take for a quantity of strontium-90 to decay to 1/16 of its original mass?
You have 180 grams of a radioactive substance. It has a half-life of 265 years. After 1,325 years, what mass remains?
Advantages and Disadvantages of Nuclear Power
Advantages Do not produce air
pollution Considered “clean” E In countries with limited
fossil fuels, can dependence on imported oil
Disadvantages Potential for nuclear
accidents Cost Disposal of radioactive
waste
Renewable Energy Potentially renewable – (as long as they are not
consumed faster than they are produced) Wood, Biofuels
Non-depleteable – can’t be exhausted w/i a human lifespan (use all the wind available today and tomorrow new wind will be available) Wind Solar Hydroelectric geothermal
Worldwide Energy Use
13 % of E use is from renewable sources 429 Exajoules or 469 Quadrillion Btu
77% of that is wood/biofuels 15% is hydroelectric 8% is solar, wind, and geothermal
Solar Energy
Passive solar systems Absorbs and stores heat from the sun directly
within a well-insulated structure Adobe, brick, concrete, stone, or water Collected as heat during the day and is released
slowly throughout the day and night Usually accompanied by a small backup system
like propane
Solar Energy
Active solar systems Captures energy from the sun by pumping a heat
absorbing fluid (water/antifreeze) through special collectors, (roof/special racks)
Some of the heat is used directly Rest is stored for later use
Solar EnergyAdvantages
Low emissions No water or air pollution No CO2 emissions Little land disturbance Low cost for passive systems Moderate amount of E Can produce E during peak
hours – hot sunny days when the demand for air conditioning is high
use of fossil fuel powered electricity
Disadvantages Requires access to sun for 60%
of daylight hours Trees and other vegetation can
grow up and block solar access High installation and
maintenance costs for active systems
Requires backup systems Can only be used in sunny areas Can require large areas of land
for CSTs Cant be used to produce E at
night
Active Solar Energy Systems Solar Water Heating Systems
Worldwide – huge numbers of countries, apartments, homes use for hot water generation
In the US – primarily used for solar heating of swimming pools
Active Solar Energy Systems Photovoltaic Systems
Solar cells capture energy directly from the sun as light, not heat, and convert it directly into electricity
Can also be used to charge batteries for later use (lighting at night)
Uses semiconductors to generate a low-voltage electric current for use in homes or businesses
PV solar cells are 12-20% efficient Can be tied into the grid to provide excess E to
power companies
Active Solar Energy Systems
Concentrating Solar Thermal Electricity Generation (CST)
The large scale application of solar E collection
Uses lenses, mirrors, and tracking systems to focus the sunlight from a large area into a single beam which is used to heat water to produce steam to turn a turbine to produce electricity
Biomass
Plant materials such as wood and agricultural waste
Crop residues Animal manure Fuelwood crisis
Biodiesel and Ethanol
Biodiesel Produced from vegetable oils
Palm oil, rapeseed, soybeans Greatest producer – European union
Ethanol Produced from corn, sugarcane, switchgrass Greatest producer - US
Hydroelectric Power
Generated by the kinetic energy of moving water
2nd most common form of renewable energy in the US and world, most widely used for electricity generation
WA, CA, OR produce over ½ of the hydroelectric power in the US
China is the world leader in hydroelectric power followed by Brazil and the US
Hydroelectric Power – 3types
Water impoundment systems Water is stored behind a dam Most common form of hydroelectric power b/c it
allows for electricity production on demand Controlled by the opening and closing of gates Largest in US is the Grand Coulee Dam in WA Three Gorges on the Yangtze is largest in the
world (China)
Hydroelectric Power – 3 types
Run of the river systems Water is retained behind a low dam and runs
through a channel before returning to the river Do not store water in a reservoir Ads: no flooding upstream, seasonal changes in
river flow are not disrupted Generally small, produce small amounts of
electricity When water flow is down electricity cannot be
produced
Hydroelectric Power – 3 types Tidal energy
Driven by the gravitational pull of the moon which causes the rise and fall of the tides
Used in France, Korea, Canada Disads:
limited usefulness because in many places the difference b/w low and high tide is not great enough to provide sufficient energy to generate a large amount of electricity
Infrastructure must be built on coastlines & estuaries, which could cause a negative impact on local ecology and tourism
Bay of Fundy Tidal Change
Geothermal Energy DOES NOT COME FROM THE SUN Comes from the heat produced from natural
radioactive decay in the earth Convection currents in the mantle bring hot
magma toward the surface. When the magma gets near groundwater, heat exchange occurs and the hot water sometimes gets to the surface by hot springs and geysers
It may be possible to reach hot water by drilling
Geothermal Energy
Hot water can be piped directly into homes for heat
Use of heat exchangers or ground source heat pumps – cool liquids are pumped down into the ground where the liquid is heated and then returned to the surface
Iceland heats 87% of its homes this way
.
Geothermal Heat Pump Water or a refrigerant moves through a loop of pipes When the weather is cold, the water or refrigerant heats up
as it travels through the part of the loop that is buried underground.
Once it gets back above ground, the warmed water or refrigerant transfers heat into the building.
The water or refrigerant cools down after its heat is transferred.
It is pumped back underground where it heats up once more, starting the process again
On a hot day, the system can run in reverse. The water or refrigerant cools the building and then is pumped underground where extra heat is transferred to the ground around the pipes
Geothermal Electricity Production
Same process as conventional production Concerns:
Requires the use of groundwater, which is not a renewable resource if it is used too rapidly
Water needs to be returned to the ground to ensure sustainability
Currently used in CA, NV, HI, UT
Geothermal hotspots
Geothermal Energy Resources
Wind Energy Uneven heating of the earth’s surface
produces winds as warmer air rises and moves toward the poles and cold air at the poles sinks and moves toward the equator
US & China produce the greatest amount of wind Energy
CA and TX produce the greatest amount of wind E currently in the US
Denmark produces 20% of E from wind
Wind Energy
Fastest growing major source of electricity in the world
Clean, non-depletable Disads:
Rely on batteries for off-grid turbines which are expensive
Noise Ugly Bird and bat deaths from collisions
Hydrogen fuel cells Device that operates like a common battery, but in
a fuel cell, the reactants are added continuously to the cell, so the cell produces electricity as long as it is supplied with fuel
Electricity is generated by the rxn of H2 & O2
Ads: Hydrogen powered cars are 80% E efficient Clean E Sustainable means of fuel for transportation
Disads: Currently net energy loss to obtain the hydrogen Storage of the gas, possible explosions
CO2 emissions by fuel source