1. Environmental Science 2
Electricity
Environmental Science 2

2. Electricity Defined Electricity is a form of energy
Electricity is a flow of charged particles, usually electrons – this is called a current
A current is not defined by how fast the charged particles move, but by how many particles move
Particles become charged when an atom either loses or gains electrons
If the atom loses an electron the particle becomes positive (because there are more positive protons than negative electrons)

3. Electricity Defined
There are several factors that cause the charged particles move
1) There has to be an electrical potential difference, meaning there has to be areas of unbalanced charges (this does not means there has to be areas of positive and negative, but regions of different charges)

4. Electricity Defined
2) There needs to be a load – a load is anything that uses electricity. The potential energy difference needs to be maintained in order to keep the current alive
3) Whether a material is a conductor or an insulator
The more available space for the current to flow the better conductor a material is (e.g. metal & water)
The less available space for the current to flow the better insulator a material is (e.g. wood & rubber)

5. Electricity Defined
4) There needs to be a complete path for the current to flow – this is called a circuit. A circuit allows the charged particle to move to through a charged region, then to the load, then through another charged area

6. Electricity Define
A closed circuit (see picture) allows the energy to flow
An open circuit does not allow the energy to flow
There are two types of connections
1) Series
2) Parallel

7. Electricity Defined Series connections Parallel connections
The energy flow moves through the area of potential energy, through all the loads, then returns to the source
Parallel connections
There is more than one path for the charges to flow – the current can bypass a load and still complete the circuit

8. How electricity is produced
The production of electricity starts with any electrically conductive material moving across a magnetic field

9. How electricity is produced
Another form of energy is needed to rotate a turbine – the most common form is steam (kinetic energy)
A conductive material is attached to the turbine
A magnetic field surrounds the turbine and generates electricity as the turbine rotates
A generator is used to collect and transfer the electricity

10. How electricity is produced
Electricity starts in the power plant
Transmission lines carry the electricity to a local substation
The electricity is then distributed to power lines and carried to sources

11. Electricity produced by fossil fuels
Coal, oil or natural gas is burned to create steam, which rotates a turbine
Over half of the U.S.’s energy comes from fossil fuels
Natural gas can also be used directly by burning the gas and the combustion gases rotate the turbine

12. Electricity produced by fossil fuels
Disadvantages of fossil fuels:
There is a finite supply of fossil fuels
Greenhouse gases are produced when burning
Advantages of fossil fuels:
Cheapest source of energy to date
Infrastructure is already in place

13. Electricity produced by wind
Uses wind turbines to generate electricity
A large number of wind turbines creates a wind plant or wind farm
The blades on the wind turbine are turned by the force of wind to rotate a turbine to produce electricity
Wind accounts for less than 1% of the country’s electricity production

14. Electricity produced by wind
Disadvantages to wind energy
At first cost was higher than traditional methods of energy production; however, now the cost is comparable to traditional methods
Not effective for areas of the U.S. with little wind
Wind is an unreliable source of energy
Wind farms are more expensive to build than coal operated plants

15. Electricity produced by geothermal energy
Geothermal power plants use steam from the Earth to rotate a turbine to produce electricity
Three types:
Dry steam: uses geysers as main source of steam – only two plants in the U.S. (Northern California & Yellowstone National Park)

16. Electricity produced by geothermal energy
Three types:
Flash steam: most common; use energy from geothermal reservoirs where water can reach around 360°F – steam is separated from the water and powers the turbine
Binary cycle: operates at lower temperatures of around 225° - 360°F – main difference between Flash Stream is the hot water is mixed with an organic compound so that the water can be reused

17. Electricity produced by geothermal energy
Disadvantages of geothermal energy:
Not enough electricity could be produced to meet U.S. demands – better for small scale areas
Geothermal energy is limited or nonexistent in some regions of the U.S
Accounts for less than 1% of the country’s electricity production

18. Electricity produced by nuclear energy
Uranium fuel rods are placed into reactor cores and then placed in water
Like fossil fuels, heat is produced and the steam turns a turbine
The turbine is then connected to a generator

19. Electricity produced by nuclear energy
Nuclear energy accounts for about 20% of the country’s electricity production
Advantages of nuclear energy:
No greenhouse gases are produced
Most viable electricity source as fossil fuels are consumed
Disadvantages of nuclear energy:
After the reaction is complete the uranium rods become radioactive
Concerns of decommissioning the plant when it is retired

20. Electricity produced by water
Utilizes stored energy from a dam (river or reservoir)
When the water is released it flows over a turbine and activates a generator
Currently the world’s largest source of renewable energy (15% of electricity)

21. Electricity produced by water
Disadvantages of hydro energy
Limited to areas of water sources
Ecological impacts include:
Downstream rivers are deprived of nutrient-rich silt because of dams
Flooding around the reservoir
Decrease in water flow inhibit fish to move up stream

22. New methods of electricity production
Solar Tower
A 3,280 ft tower, shaped much like a chimney, uses solar panels to heat air and causes the air to rise
As the air rises (much like air rising in a chimney), the air accelerates to around 35mph
The rising warm air drives 32 wind turbines inside the tower
Combining solar and wind allows the tower to operate 24 hours a day
A solar tower is schedule to be constructed in Las Vegas by the end of 2013

23. New methods of electricity production
Solar absorbing shingles
The panels can be attached to an existing roof, making it more appealing to consumers
Solar shingles will most likely be introduced in Hawaii and California due to comparable costs between fossil fuels and solar shingles
Becoming more popular in sunny areas

24. New methods of electricity production
Microbes
Researchers are testing green algae to increase the production of hydrogen gas
Once scientists perfect the output of hydrogen gas, they will then work on ways to store the gas to use in hydrogen vehicles
Researchers are also looking for ways to have bacteria produce electricity directly by placing them microbial fuel cells
Commonly placed in waste water, which helps clean the water as well as produce electricity

25. New methods of electricity production
Windmills in the sky
Windmills ft in the air to utilize the strong, persistent winds
The electricity feeds to the ground through a cable
Benefits of the project – hides the unattractive wind farms & consistent supply of wind energy
The Federal Aviation Administration has already approved the project
Problems still need to be worked out before production

26. FIGURE 1: American Electricity Demand Compared to The Top 5 Consumption Countries
Source: Energy Information Administration, Annual International Report, 2001.

27. Ways to save electricity
“Vampire” appliances
Cost consumers around $3 billion a year ($200 per household)
Satellite receivers for TV
Garage door openers
Clock radios
Answering machines
Microwave ovens and standard ovens with clocks
Computers (when left of sleep mode)

28. Ways to save electricity
Obvious ways:
Turn off lights and faucets when not in use
Do not open windows when heater/air conditioner are in use
Turn off appliances and electronics when not in use (e.g. TV, VCR, computers, radios)

29. Ways to save electricity
Less obvious ways:
Buy appliances that have the Energy Star label
Set home thermostat in winter to 68° during the day and 55° at night
Set home thermostat in summer to 78° when you are home and 85° when you are away
Use trees to help shade home and windows
Use energy efficient light bulbs

30. Ways to save electricity
Less obvious ways:
Clean or replace air filters on heater and air conditioner monthly during operating season
Wash only full loads of laundry and full loads of dishes
Do not preheat your oven when cooking or cook dishes simultaneously in the oven

31. Sources Clean Energy Basics www.nrel.gov/clean_energy
Introduction to hydroelectric power
Introduction to geothermal electricity production
Introduction to wind energy
Safe Tree Kids
How to save energy
How electricity is produced
Wired News
Solar tower of power finds home
Raise the roof: power source
Fill’er up, with microbes
Windmills in the sky
Science Blog
Cleaner electricity, cars and trucks can save consumers billions of dollars, says new UCS analysis
Bacterium cleans up uranium, generates electricity
Why burn coal when wind power is cheap and plentiful?
Energy expert:”Ampire” appliances suck electricity – even when they are off

32. Sources
Science made simple. “What is static electricity?”
Energy information administration. “What is electricity” and “Electricity generation”
Physics Post. “Circuit Basics”
Defenders of Wildlife. “Geothermal energy resources: principles and recommendations”
Energy Educators of Ontario. “Energy fact sheet: hydro-electric power”