1. Renewable Energy Sources
Energy Efficiency
- useful energy compared to energy wasted as heat
Examples
1) Incandescent Light Bulb (95% waste)
2) Nuclear Power Plant (85% waste)
3) Combustion Engine (75% waste)
4) Coal Power Plant (66% waste)
Net Energy Efficiency
- useful energy minus used & wasted energy for production

2. Energy Inputs
System
Outputs 9% 7%
41%
86%
U.S.
economy
and
lifestyles
43% 8% 3% 3%
Nonrenewable fossil fuels
Useful energy
Petrochemicals
Nonrenewable nuclear
Unavoidable energy
waste
Hydropower, geothermal,
wind, solar
Unnecessary energy
waste
Biomass

3. Electricity from Nuclear Power Plant
95%
Waste
heat
Uranium
mining
(95%)
54%
Waste
heat
Uranium processing
and transportation
(57%)
17%
Waste
heat
Power
plant
(31%)
Waste
heat
14%
Transmission
of electricity
(85%)
14%
Resistance
heating
(100%)
Uranium
100%
Electricity from Nuclear Power Plant
Window
transmission
(90%)
Passive Solar
Sunlight
100%
90%
Waste
heat
Net Energy Comparisons

4. Improving Energy Efficiency
- needs to follow two principles:
1) Limit # of steps in energy processes
2) Each step should be energy efficient
Examples:
a) Cogeneration
b) Efficient Electric Motors
c) Fluorescent Lighting
d) Increase Auto Fuel Efficiency
e) Use alternative vehicles
f) Use Better Insulation & Fix Air Leaks

5. Hybrid Car A C B D E F Combustion engine Electric motor Fuel tank
Small, efficient internal combustion engine powers
vehicle with low emissions. A
Electric motor
Traction drive provides additional power, recovers
breaking energy to recharge battery. C
Fuel tank
Liquid fuel such as gasoline,
diesel, or ethanol runs small
combustion engine. B
Battery bank
High-density batteries power electric
Motor for increased power. D
Regulator
Controls flow of power between electric
Motor and battery pack. E B
Transmission
Efficient 5-speed automatic transmission. F D E F
Hybrid Car A C
Fuel
Electricity

6. Fuel Cell Vehicle A B C D E Fuel Electricity Fuel tank Fuel cell stack
Hydrogen and oxygen combine
chemically to produce electricity. B
Fuel tank
Hydrogen gas or liquid or solid metal
hydride stored on board or made from
gasoline or methanol. C
Turbo compressor
Sends pressurized air to fuel cell. D
Traction inverter
Module converts DC electricity from fuel
cell to AC for use in electric motors. B E
Electric motor/transaxle
Converts electrical energy to
mechanical energy to turn wheels. D C E A
Fuel Cell Vehicle
Fuel
Electricity

7. Universal docking connection
Connects the chassis with the
Drive-by-wire system in the body
Body attachments
Mechanical locks
that secure the
body to the chassis
Rear crush zone
absorbs crash energy
Fuel-cell stack
Converts hydrogen
fuel into electricity
Air system
management
Drive-by-wire
system controls
Cabin heating unit
Side mounted radiators
Release heat generated
by the fuel cell, vehicle
electronics, and wheel
motors
Front crush zone
Absorbs crash energy
Hydrogen
fuel tanks
Electric wheel motors
Provide four-wheel drive
Have built-in brakes

8. Heat Energy Leaks
DO NOT POST TO INTERNET

9. Net Energy Efficiency Superinsulated house 98% Geothermal heat pumps
96%
Passive solar
90%
Passive solar + natural gas furnace
87%
Natural gas with furnace
84%
Hydroelectric heating
82%
Natural gas with typical furnace
70%
Passive solar plus wood stove
65%
Oil furnace
53%
Electric heat pump (coal-fired)
50%
High-efficiency wood stove
39%
Active solar
35%
Electric heat pump (nuclear)
30%
Typical wood stove
26%
Electric heating (coal-fired)
25%
Electric heating (nuclear)
14%

10. Types of Renewable Energy
Solar
- using the sun’s energy for heat or electricity
Types
a) Passive Heating
- individual house heating w/ no equipment
b) Active Heating
- individual house heating using equipment
c) Solar Thermal System
- collecting large amounts of sunlight for distribution
- used for heat or electricity
d) Photovoltaic Cells
- equipment that converts sunlight to electricity

11. PASSIVE SOLAR HEATING Summer sun Heavy insulation Superwindow Winter
Stone floor and wall
for heat storage
PASSIVE SOLAR HEATING

12. ACTIVE SOLAR HEATING Heat to house (radiators or forced air duct) Pump
Heavy
insulation
Hot
water
tank
Super-
window
Heat
exchanger
ACTIVE SOLAR HEATING

13. Video Links:
Ted-Ed: “How do Solar Panels Work”

14. Single Solar Cell
Boron-enriched
silicon
Sunlight
Junction
Cell
Phosphorus-
enriched silicon
DC electricity

15. Roof Options
Panels of
Solar Cells
Solar Cells

16. Solar Cell Roof

17. Concentrated Solar Power
Solar Farms

18. Solar Energy Evaluation
Pros
- Reduces air pollution & CO2 emission
- Saves money
- Low land use & disturbance
- Unlimited resource
Cons
- Need backup for night & cloudy days
Solar electrical systems are costly
Solar systems require regular maintenance
Solar systems last only years

19. Flowing Water Energy (Hydropower)
- electricity produced by:
a) Large or small dams controlling river flow
b) Tidal Energy
c) Wave Energy

20. Tidal Energy

21. Wave Energy

22. Hydropower Evaluation
Pros
- High efficiency
- Low cost electricity
- No air pollution or CO2 emissions
- Provides flood control, irrigation, & recreation
Cons
- Expensive construction
- Changes land habitats to lake
- Uproots people
- Decreases silt flow

23. Gearbox
Electrical
generator
Power cable
Wind Turbine

24. Trade-Offs
Wind Power
Advantages
Disadvantages
Moderate to high
net energy
High efficiency
Moderate startup cost
Low electricity cost
Low environmental impact
No CO2 emissions
Quick construction
Easily expanded
Land below turbines
can be used for crops or livestock
Steady winds needed
Backup systems needed during low winds
High land use for wind farm
Visual pollution
Noisy
Interferes with migratory birds

25. Conversion to gaseous and liquid biofuels
Solid Biomass Fuels
Wood logs
Charcoal
Agricultural waste
Timbering wastes
Animal wastes
Aquatic plants
Urban wastes
Biomass Energy
Use of plant materials or animal wastes for energy
Direct burning
Conversion to gaseous and liquid biofuels
Click for more info on biomass energy from National Geographic
Gaseous Biofuels
Synthetic natural gas
Wood gas
Liquid
Biofuels
Ethanol
Methanol
Gasohol

26. Trade-Offs
Biomass
Advantages
Disadvantages
Large potential supply
Moderate costs
No net CO2 increase if used sustainably
Plantations can be located on land not needed for crops
Plantations restore degraded lands
Makes use of agricultural,
timber, and urban wastes
Nonrenewable if harvested
unsustainably
CO2 emissions if used unsustainably
Low photosynthetic efficiency
Soil erosion, water pollution, and loss of wildlife habitat
Creates competition with cropland
Burned as polluting open fires

27. Hydrogen Fuel

28. Energy is needed to produce fuel Negative net energy
Trade-Offs
Hydrogen
Advantages
Disadvantages
Not found in nature
Energy is needed to produce fuel
Negative net energy
Nonrenewable if generated by
fossil fuels
High costs
Will take 25 to 50 years to develop
Short driving range for current cars
Excessive H2 leaks may deplete ozone
Produced from water
Low environmental impact
Renewable if produced from renewable energy resources
No CO2 emissions if produced from water
Good substitute for oil
Safer than gasoline & natural gas
Nontoxic
High efficiency (65-95%)

29. Geothermal Energy
Click to see an interactive geothermal power plant

30. Trade-Offs
Geothermal Fuel
Advantages
Disadvantages
Very high efficiency
Moderate net energy
Low CO2 emissions
Low cost
Low land use & disturbance
Scarcity of suitable sites
Depleted if used too rapidly
CO2 emissions
Moderate to high air pollution
Noise and odor (H2S)

31. Fuel cells Commercial Residential Industrial Microturbines
Bioenergy
Power
plants
Wind farm
Small solar cell
power plants
Fuel cells
Rooftop solar
cell arrays
Solar cell
rooftop systems
Transmission
and distribution
system
Small
wind
turbine
Commercial
Residential
Industrial
Microturbines

32. Drive cars that get 35 miles/gallon and join carpools.
What Can You Do?
Energy Use and Waste
Drive cars that get 35 miles/gallon and join carpools.
Use mass transit, walking, and bicycling.
Superinsulate your house and plug all air leaks.
Turn off lights and other electronic equipment when not in use.
Wash laundry in warm or cold water.
Use passive solar heating.
For cooling, open windows and use ceiling fans window fans.
Turn thermostats down in winter and up in summer.
Buy energy-efficient homes, lights, cars, and appliances available.
Turn down the thermostat on water heaters to 43-49ºC ( ºF) and insulate hot water heaters and pipes.

33. Essay Questions
If you had to choose, would you rather live next door to a coal-fired power plant or a nuclear power plant? Explain why, including 3 reasons against the option you don’t choose.
Solar energy, wind energy, and flowing water energy are the three best sources of renewable energy currently available. Of these three, which one do you consider to be the overall best choice? Explain 3 reasons in support of your choice and 2 reasons each against the other two you do not choose.