1. Alternative Energy Sources

2. Oil Oil fuels the modern world (gasoline, natural gas, diesel)
Easily transported, relatively safe, and versatile.
Finite resource: cost to recover will eventually exceed its value
Non-Renewable: will not replenish within our lifetime

3. Sustainability Resources “needed” = resources available
An increase in population impacts sustainability
Growth cannot be sustained indefinitely
Consider “standard of living”
A sustainable society must balance resources available with “needs” or “standard of living”

4. Alternative Sources
Alternative sources are not as convenient as oil; they require additional investment and often are not as versatile as oil
They have both advantages and limitations
Some are renewable (replenish within our lifetime) and some are not.

5. Geothermal Driven by heat from within the Earth
Water heated from the Earth’s interior can turn a turbine and generate electricity
Renewable
Limited accessibility

6. Solar Sun will exist for a long time
Promising technology (solar to electric- solar panels)
Renewable
Sunlight received is limited (related to latitude)
How store for the longterm when sun not available?

7. Wind Wind (mechanical) to electricity Clean and renewable Not reliable
End product is electricity (not a significant oil replacement)
Bird migration impacted

8. Hydro-Electric
Stored water (potential) converted to electricity (kinetic)
Non-polluting
Dams increase sediment deposition, so not truly renewable
Lowlands filled (decrease in diversity)
“Run of the river” facilities are renewable and minimize environmental degradation

9. Tidal Changes in water elevation used to generate electricity
Renewable
High tides and special shaped coastlines needed
Only nine sites worldwide
Considerable environmental impacts on estuaries (fisheries, migration routes, etc.)
Limited final product (electricity)

10. Biofuels Conversion of organic material to energy
Wood = liquid fuel, but net energy low and large environmental impact
Corn = ethanol, but negative energy gain (more energy to produce), detracts from food supplies and has a significant impact on land
Renewable

11. Nuclear Fission Splitting a nucleus yields immense energy
U-235 (.7% of all U)
U-238 used to create Pl-239 (larger source), but very toxic
Nonrenewable as Uranium reserves are limited
“Clean” fuel source
Electricity is end product
Must deal with waste products

12. Living off our Capital and Technology Limitation
*Living in a petroleum fueled economy means living off our capital
*C.G. Darwin (1952): “The fifth revolution will come when we have spent the stores of coal and oil…it is obvious that there will be a very great difference in ways of life…a man has to alter his way of life considerable, when, after living for years on his capital, he suddenly finds he has to earn any money he wants to spend…”
*Technology cannot rescue us indefinitely, as natural resources will always be necessary (food, forests, land, etc.)

13. Technology vs. Resources
Technology cannot create without resources, and our resources are finite.
How many people can a renewable energy resource support?
What will be the resources we will use to do this?
Given our current standard of living, how many people can the Earth support?