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Environmental Science

Chapter 5: Energy ResourcesSection 1: Fossil Fuels

Fuel-substance that provides energy-such as heat, light, motion, or electricity-result of a chemical change

Energy Transformation and Fuels

Energy Transformation-change from one form of energy to another

ExampleRubbing your hands together changes mechanical energy to thermal energy

Combustion-burningWhen fuels are burned they release chemical energy, which can be used to generate heat, light, electricity, motion

o ExampleGasoline in car’s engineChemical energy thermal energy mechanical energy

Production of Electricity


o Power plant-thermal energy creates steam, which turns a turbine which is connected to a generator- has magnets and copper wire-magnets turn inside wire and produce an electric current

What are fossil fuels?

Fossil Fuels-energy rich substances formed from remains of organisms

Made out of hydrocarbonsProvide much more energy than

burning wood

Hydrocarbons-chemical compounds that contain carbon and hydrogen atoms

3 main fossil fuels1. Coal-solid fossil fuel formed from plant

remainsBurned to produce heat23% of fuel used in U.S.Fuels electric power plantsBelow surface so it must be mined for-

dangerous jobMost plentiful fuel in U.S., easy to

transport, provides lots of energy


Mining increases erosion, causes water and air pollution

2. Oil-thick black, liquid fossil fuelFormed from remains of small animals, algae, and other organisms that lived in oceans or shallow inland seas millions of years ago1/3 of energy produced in the worldFuel for cars, airplanes, trains, shipsHeats homesDeposits located underground in limestone/sandstone-fill small holes in rocks-sound waves are used to locate depositsCalled crude oil when first pumped out of ground

Petroleum-another word for oilLatin words petra-rock and oleum-oil

Refinery-factory in which crude oil is separated into fuels and other products

Petrochemicals-compounds made from oil used to make plastics, paints, medicines, and cosmetics


3. Natural Gas-mixture of methane and other gases

Forms from same organisms as oil, less dense than oilTransported by pipelinesCan be compressed into a liquid

Advantageso Produces large amounts of energy

with smaller amounts of air pollution than coal/oil

o Easy to transport

Disadvantageso Highly flammable-explosion or fireo Smell added to alert people of gas

leak-natural gas has no odor

Fuel Supply and Demand Fuels are a nonrenewable resource because they take millions of years to formEarth’s coal deposits took 500 million years to form and ¼ have been used up


U.S. uses 1/3 of all oil produced in world, but only 3% is from U.S.-purchase oil from other countries, which leads to political problems

Chapter 5: Energy ResourcesSection 2: Renewable Sources of Energy

Harnessing the Sun’s Energy

Solar Energy-energy from sun, given off as heat and light

Each day sun gives us enough solar energy to last 40 yearsCauses no pollution and will not run outBut it is not sunny every day and the distribution of sunlight is not even

o Solar Power Plants-rows of mirrors that focus the sun’s rays to heat a tank of water, which boils and produces steam, which is used to generate electricity


o Solar Cells-like a battery (negative and positive ends)-when light hits cell, it produces electric currentPower calculator and small lights/devices

o Passive Solar Heating-converts sunlight into thermal energydistributed without pumps or fans

Ex: how a car is heated inside on a hot day

o Active Solar Heating-captures sun’s energy and uses pumps/fans to distribute heatSunlight heats solar panel which heats water which flows in a tank and pumps throughout building

Hydroelectric Power-electricity produced by flowing water

Most widely used source of renewable energy

Provides steady, inexpensive flow of energy that does not produce air pollution


Limitations-most rivers in U.S. have been dammed, which cause environmental problems

Ex: dams-block flow of water to create a reservoir-when floodgate opens, water flows through gates into tunnels, which turn turbines to power a generator

Capturing the WindIndirect form of solar energy caused by uneven heating of Earth’s surface-this causes air pressure differencesCan be used to turn a turbine and generate electricity-windmills-fast growing energy sourceDoes not cause pollutionFew places have winds that blow steadily enough to generate much powerWind generators are noisy and can be destroyed by strong winds

Biomass Fuels-fuels made from living thingsWood, leaves, food waste, manureHawaii-burn sugar canes to generate

electricity


Renewable resource, but trees take many years to replace

Expensive-not widely used in U.S

Gasohol-mixture made from alcohol and gasoline-used as fuel for cars

Tapping Earth’s Energy

Geothermal Energy-intense heat from Earth’s interior that warms magma

Unlimited source of cheap energyOnly few places where magma comes close enough to Earth’s surface

Ex: New Zealand and Iceland-magma heats underground water to boiling which can produce steam to create electricity-many homes in Iceland heated this way

The Promise of Hydrogen Power

Hydrogen(H)-ideal fuel, but most on Earth is combined with oxygen as water (H2O)-must


extract H out of water, but this takes a lot of energy


Chapter 5: Energy ResourcesSection 3: Nuclear Energy

Nucleus-central core of an atom that contains protons and neutrons

Nuclear FissionAlbert Einstein (e=mc2)

E=energy, m=mass, c= speed of lightWhen matter changes to energy, an enormous amount of energy is released

Fission ReactionsNuclear Fission-splitting of atom’s nucleus into 2 smaller nuclei

Fuel for reaction-unstable nucleus (Uranium-235)

When neutron hits U-235 nucleus, it splits into 2 smaller nuclei and 2 or more neutronsMass of new material is less than mass of original nucleus-the rest has been converted to energy

Energy from Fission


If nuclear chain reaction is not controlled, released energy causes explosion (atomic bomb)If reaction is controlled, it can generate electricity

Nuclear Power PlantsHeat is used from fission to change water into steam, which turns a turbine to generate electricity

Reactor Vessel-part of nuclear reactor where fission occurs

Fuel rods-rods of U-235, many rods are placed together for a series of fission reactions

Control Rods-used to slow down reactions, made of metal cadmium, inserted between the fuel rodsCan be removed to speed up reactions

Heat Exchanger- water/fluid boils to produce steam which runs a generator

Risks of Nuclear Power


Safety concerns1986-Chernobyl, Ukrainepower plant overheated meltdown-series of explosions which injured/killed dozens of peopleRadioactive materials escaped into environment and remain dangerous for many years

Meltdown –fuel rods generate so much heat that they melt

The Quest to Control Fusion

Nuclear Fusion-combining 2 nuclei to produce a larger nucleus

2 H nuclei combine to create a Helium (He) nucleus

He nucleus has less mass than H nucleus, lost mass converted to energyWater=fuel for reactionProduces less harmful waste than fissionPressure and temp. required for this reaction make it impractical at this time


Chapter 5: Energy ResourcesSection 4: Energy Conservation

What would happen if we ran out of fossil fuels today?

No heat/air conditioning Forests would disappear because everyone

would have to use wood for energy No vehicle transportation 70% of electric power would disappear Communication would be reduced No household appliances

Energy Efficiency

Efficiency-percentage of energy that is actually used to perform work

Rest is lost to surroundings usually as heat

Heating and Cooling

Insulation-layer of material that traps air to help block the transfer of heat between air inside and outside a building


Ex: fiberglass, air in between panes of glass in window

Lighting

Most light is wasted energy given off as heat

Fluorescent bulbs use less energy to produce the same amount of light as incandescent bulbs

Transportation

Better engines and tiresReduce cars on the road with public

transportation and carpooling

Energy Conservation-reducing energy useWalk or ride a bike for short tripsRecycleUse fans instead of air conditionersTurn off lights and TV when not in a room

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