Do Now: Energy Move Clip

• Answer the following questions in your notebook.

1) What is energy? 2) List 4 types of energy from the clip.

Aim: How is energy wasted?

Case Study: A Brief History of Human Energy Use

• Everything runs on energy

• Industrial revolution began 275 years ago, relied on wood… led to deforestation

• Today we rely on:

- Coal

- Petroleum products

- Natural gas

Why do you think the world as a whole relies more on renewable energy than

the U.S. does?

Fig. 15-1, p. 370

Net Energy Is the Only Energy That Really Counts

• First law of thermodynamics:– It takes high-quality energy to get high-quality

energy– Ex: Pumping oil from ground, refining it,

transporting it

• Second law of thermodynamics– Some high-quality energy is wasted at every step

Do you understand the 2 laws of thermodynamics?

It Takes Energy to Pump Petroleum

Fig. 15-2, p. 372

Pumping Petroleum Movie Clip

• How do we get oil from the ground?

Net Energy Is the Only Energy That Really Counts

• Net energy – Total amount of useful energy available from a

resource minus the energy needed to make the energy available to consumers

Net Energy Ratio

• Ratio of energy produced to energy used to produce it.

• Conventional oil: high net energy ratio

Do you understand net energy?

Net Energy Ratios

Fig. 15-3, p. 373

Fig. 15-3a, p. 373

Space Heating

Passive solar 5.8

Natural gas 4.9

Oil 4.5

Active solar 1.9

Coal gasification 1.5

Electric heating (coal-fired plant) 0.4

Electric heating (natural-gas-fired plant) 0.4

Electric heating (nuclear plant) 0.3

Fig. 15-3b, p. 373

High-Temperature Industrial Heat

Surface-mined coal 28.2

Underground- mined coal 25.8

Natural gas 4.9

Oil 4.7

Coal gasification 1.5

Direct solar (concentrated) 0.9

Fig. 15-3c, p. 373

Transportation

Natural gas 4.9

Gasoline (refined crude oil)

4.1

Biofuel (ethanol) 1.9

Coal liquefaction 1.4

Oil shale 1.2

Do you understand the net energy ratio?

Energy Resources With Low/Negative Net Energy Yields Need Marketplace Help

• Cannot compete in open markets with alternatives that have higher net energy yields

• Need subsidies from taxpayers…Is this good or bad?

• Nuclear power as an example

Reducing Energy Waste Improves Net Energy

• 84% of all commercial energy used in the U.S. is wasted– 43% after accounting for second law of

thermodynamics

• Drive efficient cars, not gas guzzlers

• Make buildings energy efficient

Summary:

• Typical citizens of advanced industrialized nations each consume as much energy in 6 months as typical citizens in less developed countries consume during their entire life.

• Why is this? Will this ever change?