The document discusses various renewable energy technologies including solar, wind, biofuels, geothermal, hydroelectric, and hydrogen. It outlines the advantages and disadvantages of each technology, how much they currently contribute to energy production, and barriers to their increased adoption such as high costs, land use requirements, or lack of infrastructure. Improving energy efficiency is also highlighted as having potential to significantly reduce wasted energy.

1. Renewable Energy Technology
• Solar Power
• Wind Power
• BioFuels
• Geothermal Power
• Hydroelectric
Power
• Hydrogen

2. What are Our Energy
Needs?
1. Energy for Transportation
2. Energy for Buildings
3. Energy for Industry

3. What Role Does
Energy Efficiency Play?
Approximately 84% of commercial energy in US is
wasted.
1. 41% because of the second law of thermodynamics
(high quality energy to low quality energy in
reactions)
2. 43% because of inefficient cars, furnaces,
appliances, and poorly insulated buildings.

4. Solar Power
Pro’s Con’s
• High net • Need access to
energy sun
• No CO2 • Need storage/
backup system
• Low environ-
mental impact • High cost
• Reduces • High land use* Solar Array in Arizona
dependence on
fossil fuels
• Low efficiency
• Work on
cloudy days*

5. Wind Power
Advantages
1. Most rapidly growing source of energy.
2. Only 1% in US now, but 1.5% in CA.
3. Inexpensive and clean.
Disadvantages
1. Need lots of space and wind.
2. Midwest US (Texas and the Dakotas, too).
3. Primary drawbacks are visual pollution
and migratory and predatory bird mortality.

6. BioFuels
Pro’s of Biofuels
•
Stimulate rural
agrarian communities
•
Relieve dependence
on Middle East oil
•
Cut CO2 emissions
(biofuels release CO2
taken from
atmosphere,
theoretically carbon-
neutral)

7. Biofuels Continued...
Con’s of Biofuels
1. Herbicides, pesticides,
fertilizers used now on
corn
2. Soil erosion
3. Producing corn ethanol
uses as much fossil fuel
as it replaces
4. Biodiesel from
soybeans is similar
Sugarcane in Brazil

8. Biofuels
Cons (continued)
4. Rising prices for these crops
will push farmers to cultivate
35 million more acres of
marginal farmland that are now
set aside for soil conservation
and wildlife management
6. This production for biofuels
will raise prices for food from
beef to corn flakes
Ethanol facility in Brazil

9. Geothermal Power
Pro’s Con’s
• High efficiency • Shortage of
suitable sites*
• Lower CO2
• Depleted if used
• Low cost at too rapidly
favorable sites
• CO2 emissions
• Low land use
and distubance • Moderate/High
air pollution
Geothermal Plant in California
• Moderate
environmental • High cost*
impact

10. Hydroelectric Energy
Hydroelectric. Produces 6% of
the world’s commercial energy
(4% in US), but 20% of the
world’s electricity (10% US).
This can be misleading… on the
West Coast 63%.
Large Scale: High Dam is build
across the river, creates lake.
Water flows through pipes in the
dam to turn turbines and power
generators which produce
electricity.
Small Scale: Low dam built (no
lake) turbines power generator to
produce electricity.

11. More on Hydroelectric
Pluses
1. High net energy, high efficiency, low cost
2. No CO2
3. Flood control
4. Irrigation possibilities
Negatives
1. Disrupts natural water/nutrient flow of river
2. Interrupts fish migrations
3. Floods land areas (large scale dams)
4. High construction costs

12. Hydrogen and Fuel Cell
Technology
• Advantages
• abundant sources of H2
• clean fuel (H2O produced as waste)
• Disadvantages
• obtaining the H2 from water and other sources
uses a lot of energy (carbon footprint)
• lack of hydrogen delivery infrastructure