renewable energy

1. Session 11 - Renewables
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Biomass
Geothermal
Hydro
Solar
Ocean Based
Wind

2. Renewable Sources
• Solar
• Gravitational
• Radioactive
All have a nuclear history

3. Attractiveness of Renewables
Generally:
• It’s abundant, available everywhere
• Does not deplete Earth’s resources
• Minimal environmental impact

4. Challenges
• Technological Challenges
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Low capture efficiency
Low energy density
Lack of dispatchability
Environmental issues
• Integration Challenges
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Small present contribution
High capital costs
Materials ramp up limitations
Storage, location vs. load, transmission lines
Output versus load requirements

5. Overview of Conversion Processes
• Solar
– Photons to electricity (photoelectric effect)
– Electromagnetic wave to heat (absorption)
– Thermal expansion to kinetic
– Electromagnetic wave to chemical (photosyn.)
– EM wave to phase change, storage (hydro)

6. Overview of Conversion Processes
(continued)
• Gravitational
– Potential energy to Kinetic energy (hydro)
– Differential kinetic energies (ocean)
– Thermal energy from plates, magma
• Nuclear
– Nuclear to thermal (radioactive decay of K, U,
Th in Earth’s interior)

7. Renewables - 2007

8. Saturation
US Energy Consumption is ~ 100 Quads.
By 2050 with 2% annual growth: 230 Q
Scenario 1: No conservation, grow wind
and solar from levels of 0.4 Q in 2006 by
15% annually: 187 Q in 2050
Scenario 2: Conservation (1% growth),
grow wind and solar by 10% annually:
152 Q needed; 27 Q from renewables

9. Policy
• Minnesota’s Next Generation Renewable Energy
Objective of 2007:
– 25% of electrical energy must derive from renewable fuel by
2025 (30% for Xcel Energy)
• US Energy Policy Act of 2005
– Temporary tax breaks for biodiesel
– Breaks for closed-loop biomass, solar, wind, geothermal (closed
loop = grown exclusively for power production)
– Lesser breaks for open-looped biomass, landfill gas,
hydroelectric
• Minnesota Sustainable Forest Resources Act of 1995
– Provides for multiple uses of forests
– Directs Department of Natural Resources to monitor

10. Policy
• Minnesota’s Next Generation Renewable Energy
Objective of 2007:
– 25% of electrical energy must derive from renewable fuel by
2025 (30% for Xcel Energy)
• US Energy Policy Act of 2005
– Temporary tax breaks for biodiesel
– Breaks for closed-loop biomass, solar, wind, geothermal (closed
loop = grown exclusively for power production)
– Lesser breaks for open-looped biomass, landfill gas,
hydroelectric
• Minnesota Sustainable Forest Resources Act of 1995
– Provides for multiple uses of forests
– Directs Department of Natural Resources to monitor