Here are potential responses to some of the questions: - The most promising alternative energies currently seem to be solar, wind, and hydroelectric due to declining costs and environmental benefits compared to fossil fuels. Geothermal also shows promise. - Solar panels on homes typically produce thousands of watt-hours (kWh) per year, depending on the size of the system. Large solar farms can produce multiple megawatt-hours (MWh). - Based on the information provided, the least expensive alternative energy currently is hydroelectric, followed by wind and geothermal. Solar PV costs have declined significantly but are still more expensive than some other renewables. - It would depend on the size of the solar cells

1. Energy
It takes energy to do
work.
Energy is important for
our health, comfort and
prosperity.
Energy and power are
different things. Power
describes how quickly
work can be done.
Energy is how much
work is done.
Energy you use directly:
-Transportation
-Household
-heating and cooling
-cooking
-cleaning
-refrigeration
-entertainment
-communication

2. Measuring Energy
• Energy is a measurable thing. It is how much work has
been done, or how much work can be done
– Calorie
– Watt-hour (kWh, MWh, TWh)
– British Thermal Unit (BTU)
A tank of gasoline.
Electricity used at home by a family of 4 in one week.
Which is more energy?:

3. Major Sources of Energy
for Planet Earth
Nuclear Fusion
• Sun
1) Coal
2) Petroleum
3) Natural Gas
4) Biomass
5) Hydroelectric
6) Wind
7) Solar
• Plasma Reactors
(experimental, presently a
net energy loser)
Nuclear Fission
• Reactors
• Geothermal
Gravitational
• Tidal
Combustion ( burning )
“Alternative Energy”

4. This bubble graph shows the amount of energy available to us on
planet earth. It is important to understand the “renewables” on this
graph are available to us each and every year, while the “finites” are
stored energy that took millions of year to accumulate.
Available Energy Resources

5. Alternative Energy Questions
• When will we run out of fossil fuels?
– It’s hard to say, but it will be a long time before we
are “out.” We are using fossil fuels much faster
than nature can produce them. They will become
more difficult to obtain and thus more expensive.
• When will the earth become totally polluted
by using fossil fuels and nuclear fission?
– Probably never. We understand how to control
toxic waste and emissions, but this adds greatly to
the cost of electricity generated by them.

6. Why Alternative Energy Now?
• Alternative energy is a valuable resource
literally all around us. Smart people are
figuring out ways to exploit it for everyone's
benefit.
• It took over a hundred years to build the
energy system we have today. Even now, many
parts of the world do not have reliable access
to energy. It will take a long time to build the
alterative energy infrastructure.

7. Cost of Energy
0 0.1 0.2 0.3 0.4 0.5 0.6
Hydro
Wind
Geothermal
Solar PV
Biomass
Natural Gas
Coal
Nuclear
US $ per kWh
Cost of Energy, 2013
This is how much electricity cost in 2013 for the various
energy sources. LCOE is one way to compare the
economics of these sources.

8. Availability of Alternative Energy
Sometimes Available:
Wind – Speed can be too high or too low to run the turbines
Solar – Only when the sun shines. Daytime and cloudless days
Always available:
Hydroelectric
Biomass
Tidal
Geothermal

9. How We Use Energy*
*2013
https://flowcharts.llnl.gov/
“Quads” are Quadrillion BTU

10. Nega-Watthours,
the Most Efficient Energy
• Reducing wasted energy is negative energy used.
• More than half the energy we consume is wasted.
– A conventional light bulb gets hotter than an LED bulb.
– A refrigerator takes heat out of the food and puts in
the house. Then the air conditioner takes the heat out
of the house and puts it outside.
– Lighting empty rooms, and cooling or heating homes
when nobody is home.

11. STEM Challenge
• Figure out how much energy you use in a
month as measured in kWh
– Identify sources
– Determine Quantities: Gallons, Cubic Feet, kWh
– Convert all to kWh (find converters on WWW)
– Divide by number of people using the energy
– Report the number, compare and discuss
– Bonus: Calculate cost per kWh for each source

12. Text questions asked by the students:
• So what alternative energies seem most promising for economic and environmental feasibility?
• How much energy do the solar panels produce?
• What alternative energy source is the least expensive?
• Approximately how many solar cells could power our school? Could you think of an estimate?
• I saw a video idea the other day on Facebook. The idea was that instead of using gravel to make roads, the roads would be made out of solar panels.
• Could there be any currently unknown alternative energy sources?
• How long (In years) do you think it will take until "Alternative" energies become the primary sources of energy
• Approximately how many more years will it take for us to use up all of our primary energy sources?
• What is the real point of using energy? (not cause it provides us with electricity)
• How long will it take for our primary sources to be used up?
• What is the quickest growing alternative energy.
• Does the US ever try to help other countries without energy?
• What are the biggest issues with each alternative energy
• Is there a most efficient energy source?
• What interested you in the solar business?
• Could alternative energy be used to make cars and daily objects work better?
• How is the energy transferred from the alternative sources ?
• What are the best ways to not waste energy?
• If any what situations would there be that "Alternative" energies are preferable more efficient more cost efficient?
• Are there ways to reproduce the energy that the sun gives off?
• If any what situations would there be that "Alternative" energies are preferable more efficient more cost efficient than traditional sources of energy?