1. Part 1 – Types, Usage, and Projections
Energy
Part 1 – Types, Usage, and Projections

2. Definitions Energy = the ability to do work Power = work/ time
Measured in joules
Power = work/ time
Measured in watts = joules/second

3. Forms of Energy Form Description Mechanical
Two types, potential (“resting energy”) and kinetic (“moving energy”)
Thermal
Heat – the vibration and movement of atoms and molecules within substances
Chemical
Stored energy in chemical bonds
Electrical
Energy from the motion of electrons
Nuclear
Energy stored in the nuclei of atoms
Electromagnetic
Energy that travels by waves

4. Power and Units Unit or Prefix Description Btu (British Thermal Unit)
>Amount of energy required to raise the temperature of 1 lb. of water by 1°F.
>Unit of energy used in the US (most other countries its joule)
>1 watt = 2.3btu/hr
Horsepower
>1 horse power = 746 watts = 2,540 btu/hr
>primarily used in the auto industry
Kilo-
> 1,000 or 103; 1kW = 103 watts
Mega- (M)
>1,000,000 of 106; 1MW = 106 watts
Kilowatt hour (kWh)
>Unit of energy = 1,000 watt hours or 3.6 megajoules
> Commonly used for billing

5. Conversions – Sample APES problems
Thorpeville is a rural community with a population of 8,000 homes. It gets electricity from a small, municipal coal-burning power plant just outside of town. The power plant’s capacity is rated at 20 megawatts with the average home consuming 10,000 kilowatt hours (kWh) of electricity per year. Residents of Thorpeville pay the utility $0.12 per kWh. A group of entrepreneurs is suggesting that the residents support a measure to install 10 wind turbines on existing farmland. Each wind turbine is capable of producing 1.5 MW of electricity. The cost per wind turbine is $2.5 million to purchase and operate for 20 years.

6. Conversions – Sample APES problems
a) The existing power plant runs 8,000 hours per year. How many kWh of electricity is the current plant capable of producing?

7. Conversions – Sample APES problems
b) How many kWh of electicity do the residents of Thorpville consume in one year?

8. Conversions – Sample APES problems
c) Compare answers in (a) and (b). What conclusions can you make?

9. Conversions – Sample APES problems
d) Assuming the population of Thropeville remains the same for the next 20 years, and that elecricity consumption remains the stable per household, what would be the cost (expressed in $ per kWh) of electricity to the residents over the next 20 years if they decided to go with the wind turbines?

10. Conversions – Sample APES problems
e) What are pros and cons of the existing coal-burning plant compared to the wind farm? (Hint: use information you calculated plus what you know about these forms of energy)

11. Conversions – Sample APES problems
An electric water heater requires 0.30 kWh to heat a gallon of water. The thermostat is set to 150°F. The cost of electricity is $0.20 per kWh. A washing machine with a flow rate of 6.0 gallons per minute runs four times each Saturday. Each time is runs it takes in water for a total of 15 minutes.

12. Conversions – Sample APES problems
a) How much total water does the washing machine use in one year?

13. Conversions – Sample APES problems
b) Calculate the annual cost of the electricity for the washing machine, assuming that 3.0 gallons per minute of the water used by the machine comes form the hot-water heater.

14. Thermodynamics 1st law: Energy cannot be created or destroyed.
2nd law: When energy is converted from one form to another, a less useful form results (energy quality). Energy cannot be recycled to a higher quality.

15. Energy consumption Prehistory to industrial revolution – wood
Industrial revolution to mid 20th century – coal
Mid 20th century to today – petroleum
Natural gas and coal experience booms in later half of the 20th century due to technological advances

16. Energy consumption by Source

17. Energy consumption in the US
US was self-sufficient until the late 1950’s
Then consumption began to outpace production leading to oil imports
What happened to change this?

18. Energy consumption by sector
Industry > transportation > residential > commercial

19. Petroleum In 1998, net imports of oil surpassed the domestic supply
US accounts for 25% of world consumption of petroleum

21. US Production vs. Consumption
In US most energy comes from non-renewable sources
Renewable = biomass, geothermal, hydropower, solar energy, and wind energy
Commodity
US Production
US Consumption
Oil
18%
39%
Natural Gas
27%
23%
Coal
33%
Nuclear
10% 7%
Renewable 9%
3.6%
Hydroelectric 5% 4%

22. US Energy Commodity Consumption Commodity % of total world usage Oil
Production By Sector
Sector %
Transportation 27
Industrial 38
Residential and commercial 36
Commodity Consumption
Commodity
% of total world usage
Oil 40
Natural Gas 23
Coal

24. Future Energy Sources Short-term Fossil Fuels
Most economic, reliable, and realistic sources of energy are:
Already have the infrastructure and technology to acquire
Not the most Environmentally Friendly
Will run out of some day
Long-term
Renewables
Nuclear
Need to develop infrastructure and technology to make efficient
Eg: charging stations for electric cars and car batteries that can charge in minutes not hours