Energy an overview. How many different sources of energy can you name? Oil Coal Natural gas Biomass...
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Transcript of Energy an overview. How many different sources of energy can you name? Oil Coal Natural gas Biomass...
How many different sources of energy can you name?
• Oil• Coal• Natural gas• Biomass
– Biofuel crops– Wood– animal dung
• Solar– Photovoltaic– heat
• Wind
• Nuclear• Fuel cell• Tidal• Current• Wave• Hydroelectric
– Large– Small
• Geothermal
How many are solar based?
• Oil• Coal• Natural gas• Biomass
– Biofuel crops– Wood– animal dung
• Solar– Photovoltaic– heat
• Wind
• Nuclear• Fuel cell• Tidal• Current• Wave• Hydroelectric
– Large– Small
• Geothermal
What is energy, anyway?
• The ability to do work
• That is: gives the ability to move things
• It is force multiplied through a distance
• Key: Energy takes a variety of forms, but all forms can be used to do work.
Some energy units• British Thermal Unit (BTU)
– Amount of energy needed to raise one pound of water one degree F.– Roughly: the energy in a kitchen match– 1 candy bar has about 1,000 BTUs
• Joule– 1,000 joules = 1 BTU– About one million in a donut– Rarely used in polite conversation, but kilowatt-hours are just a fancy way of referring to
joules
• Heat can be equivalent to mechanical energy– 1 calorie = 4.186 joules– 1 calorie raises one gram of water by one deg. C– Food calories are in reality Kilocalories
Power
• The rate of doing work
• One watt = 1 joule/second
• We pay for electricity by the energy consumed, NOT the rate at which it is consumed.
• Usually: kilowatt-hours:
• = 1000 J/sec x 3600 sec = 3.6 x 106 J
Power vs. energy
• Go to the gas station. Fill your tank. Are you paying for the gasoline (energy) or the rate that you pumped the gasoline (power)?
• With electricity, you pay for the energy, not the rate you use it. So, you pay for kilowatt-hours, not kilowatts.
Energy conservationvs
Conservation of energy
• Conservation of energy: 1st law of thermodynamics says ``energy cannot be created or destroyed’’
• Energy conservation: Try to do things using as little (nonrenewable) energy as possible
Entropy
• Energy always deteriorates, becoming less usable
• 2nd law of thermodynamics: energy decays from a more usable to a less usable form– ENTROPY INCREASES
• Usable energy lost as heatemphasizes importance of conservation
Energy is at the root of many environmental issues
• Global warming
• Air pollution
• Sprawl
• Municipal waste (cheap energy means discard rather than reuse)
• Industrial agriculture
• Loss of habitat
Fossil fuels
• Formed hundreds of millions of years ago—before the dinosaurs
• From the remains of plants and animals, many tiny
• Cooked – pressure and temperature (as well as starting material) determine the fate
Types of coal
• Lignite SOFT
• Subbituminous
• Bituminous
• Anthracite HARD
• Highest in water, lowest in btu/lb
• High water content, slightly higher btu/lb
• Lower water content, higher btu/lb, HIGH in SULFUR
• Lowest in water, highest in btu/lb, low in sulfur, most expensive
coal
• Mostly carbon
• A chunk of coal contains practically every other element – Sulfur– Heavy metals
The U.S. . . • . . . is the Saudi Arabia of
coal• In 2004, the US
government estimated that Wyoming had about 42 billion tons of mineable coal in the ground– Enough for the entire US
for about 40 years!
Coal
• Safety problems– Black lung disease– Mine disasters
• Legislation– Surface Mining Control and Reclamation Act
• 1977, required that open pit mines, once left as is, had to be reclaimed.
• Prohibits coal mining in sensitive sites, such national parks, wildlife refuges, etc.
Coal
• ASH = unburned particles– 98% is captured, landfilled– So, 2% released particulates
• SULFUR = in most coal, reacts with oxygen to form SO2 and then in atmosphere to form sufuric acidacid rain
• CARBON DIOXIDE
Oil and Natural Gas
• Oil: forms from microscopic aquatic organisms that die and are buried, absence of oxygen
• Natural gas: forms similarly to oil, but at higher temperatures
• Marine organisms deposited in dead zones on ocean floor—no aerobic decomposition. Formed SOURCE ROCK for most oil.
World’s first oil well
• 1859, near Titusville, PA
• 3 months before Darwin published On the Origin of Species
• Whale oil getting scarce
• kerosene
Oil production: US
• What do you think is happening to U.S. oil production (i.e. the number of barrels of oil produced each day from U.S. wells)?
•
Peak oil
• Pay attention to this: you’ll be hearing a lot more about it.
• Key point: There is a finite amount of oil. At some point, the production of oil—the removal of oil from the ground—will peak and start to decline. That point is now.
• Another way of saying it: peak oil is the maximum daily global production of oil. After the peak, it’s downhill.
Peak oil
•
Saudi Arabia's King Abdullah told his subjects in 1998, "The oil boom is over and will not return... All of us must get used to a different lifestyle."
— Abdullah S. Jum'ah, 2008-
01[119]
``I do not believe the world has to worry about ‘peak oil’ for a very long time.’’ President of Saudi Aramco
”
Implications of peak oil
• What will happen if oil production declines?
• Think about all the things that use oilsee figure 19.11 in the textbook
Impacts of using fossil fuels
• All: carbon dioxide – a byproduct of combustion
• Coal: acid mine drainage – minerals in exposed rock interact with water.
• All: habitat destruction –mt.top removal for coal; disruption of habitat for oil/gas -ANWR
• Coal: acid rain• All: air pollution—particulates,etc.
Acid mine drainage
• Water runoff from an abandoned coal mine
• Water often pumped out of coal and metal mines so work can go on
• Interaction of air, water and rock or coal generates acidity
Conserving energy
• Cogeneration– Capturing and using waste heat from other
processes• Sometimes, the heat is used to warm up buildings
in a cold area• Sometimes, the heat is used to boil water to make
electricity
Efficiency
• No process uses energy 100% efficiently– (1st and 2nd laws)
• Typical power plant: 33%
• Incandescent light bulb: 5 %
• Fluorescent light bulb: 20%
Energy input, (BTUs) per person, per mile
• Automobile (driver only) 6530
• Transit bus (9 p.) 4235
• Airplane – commercial 3261
• Commuter Rail(31 p.) 2996
• Carpool 2230
• Motorcycle 1855
• Vanpool (6 p.) 1094