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

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?:

Major Sources of Energy for Planet Earth

Nuclear Fusion• Sun

1) Coal2) Petroleum3) Natural Gas4) Biomass5) Hydroelectric6) Wind7) Solar

• Plasma Reactors (experimental, presently a net energy loser)

Nuclear Fission• Reactors• Geothermal

Gravitational• Tidal

Combustion ( burning ) “Alternative Energy”

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

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.

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.

Cost of Energy

Hydro

Wind

Geothermal

Solar PV

Biomass

Natural Gas

Coal

Nuclear

0 0.1 0.2 0.3 0.4 0.5 0.6

Cost of Energy, 2013

US $ per kWh

This is how much electricity cost in 2013 for the various energy sources. LCOE is one way to compare the economics of these sources.

Availability of Alternative EnergySometimes Available:Wind – Speed can be too high or too low to run the turbinesSolar – Only when the sun shines. Daytime and cloudless days

Always available:HydroelectricBiomassTidalGeothermal

How We Use Energy*

*2013https://flowcharts.llnl.gov/ “Quads” are Quadrillion BTU

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.

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

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?