Alternative Energy Sources

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

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”  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”

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.  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.

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

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?

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

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

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)

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

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

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.)

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?