Energy: Systems a nd Solutions

1. - + H2 O2 Energy: Systems andSolutions

2. Why Are We Going Here? • NYS Science Standard 4, Key Idea 3: Energy exists in many forms, and when these forms change energy is conserved. • The first fossil-fuel power plants were around 4% efficient. Today’s fossil fuel plants are ~40% efficient. • Is this good enough?

3. U.S. Energy Consumption

4. World Energy Consumption

5. Sources of U.S. Energy US EIA: www.eia.doe.gov

6. The Energy Gap

7. Delivering Energy

8. Conflicting Messages Point: A recent Wall Street Journal opinion editorial article states, “There’s an unavoidable problem with renewable-energy technologies: From an economic standpoint, they’re big losers”.M. Schulz, “Don’t count on ‘countless’ green jobs,” Wall Street Journal, 20 February 2009, p. A15. Counterpoint: • In 2000, solar cells typically used 15 g of expensive, highly refined silicon to generate 1 W of power. By comparison, new SunPower modules currently use only 5.6 g/W. The manufacturing cost of standard crystalline silicon modules produced in a state-of-the-art facility today is around $1.40/W. Swanson, Richard M. Photovoltaics Power Up, Science, 324, 891, 2009.

9. “With Great Power Comes Great Responsibility…” --Uncle Ben • We efficiently consume ever-increasing amounts of energy What’s in your pocket?

10. Energy Sources Sources Coal Crude oil Natural gas fossil biogenic Solar Energy Nuclear fusion biogenic Biomass photosynthesis Heat/light Wind Waves Precipitation Streams Earth Crust Nuclear fusion fossil mineral Uranium Geothermal Planet Movement Tide Energy Fluxes Energy Carriers

11. The Hydrogen Cycle

12. Synthetic Hydrocarbons

13. Fuel Cells • Conversion of potential to kinetic energy • Minimal heat generation

14. DMFC PAFC PEM SOFC Portable electronics Portable electronics SOFC II DMFC PAFC In space PEM SOFC Stationary (buildings) Automotive Fuel Cell Application Space MCFC AFC Automotive typical operating temperature ~ -10ºC >140ºC 600ºC ~1,000ºC complexity of fuel increasing increasing allowable contaminants in H2 Fuel Used can vary with temperature (general rule of thumb) require reformers, or very clean H2 can run on direct hydrocarbon fuels, or “dirty” H2

15. Fuels and Equivalent Energy Density

16. Wind • The fastest growing technology among renewable resources • China, U.S., Germany, Spain, India, and Italy are the top six wind installers (2010) World Wind Energy Association

17. No More Nukes? Green Chemistry, Manahan, S. E., 2005

18. The Nuclear Lifecycle Settle, F. A. Journal of Chemical Education, Vol. 86 No. 3 March 2009

19. DOE’s stance

20. Fukushima Daiichi

21. Geothermal Geography • Sources and sites are limited • No new discoveries

22. Plants: Our best solar cells? Let nature do the work (we can take the credit)

23. Corn-per-car area Pietro, W. J. Journal of Chemical Education, Vol. 86 No. 5 May 2009 •  • A trip down the path to the first law of thermodynamics • Reactions at work in photosynthesis and fermentation

24. Corn-per-car area Pietro, W. J. Journal of Chemical Education, Vol. 86 No. 5 May 2009 •  • Sunlight power • At 30-45° latitude, photon density is 240 W/m2 • Only 43% is photosynthetically active = 103 W/m2 • At best, farms can utilize 80% of the area = 82 W/m2 • Photosynthetic efficiency • Photosynthesis requires 8 moles of photons to synthesize one molecule of carbohydrate = 8 x 216 kJ = 1.7 x 103 kJ • The ΔG (free energy of formation) of carbohydrate from CO2 and water is 528 kJ • The overall photosynthetic efficiency is 528 kJ/1.7 x 103 kJ = 0.31 • The plant grows ~200/365 days per year, or a 0.55 duty cycle • Plant requirements • Only 30% of the corn plant can be used to produce carbohydrate for ethanol

25. Corn-per-car area (cont’d) • Fermentation chemistry • The fermentation of carbohydrate to ethanol requires has a ΔG of -278 kJ/mole • 18% of the original solar energy are used by yeast for fermentation, leaving 82% in the ethanol • Automobile use • We consume 750 billion kilograms of gasoline for cars • There are 500 million cars in the world • This amounts to 7.0 x 107 kJ of energy per year per car

26. Corn-per-car area (cont’d) • Energy conversion • 82 W/m2 = 2.6 x 106 kJ/(year m2) • Multiply by efficiency factors: • Land requirements: • This is equal to ~7,000 ft2 per car • Other considerations: Carbohydrates available for fermentation, actual duty cycle, fermentation efficiency, production overhead

27. PV and Land Use

28. Maximum Solar Cell Efficiencies

29. A Quote… • “Our energy future is becoming clearer. PV will not be a panacea, but it will take its place as a major source of energy alongside energy efficiency, other renewables, nuclear, and improved conventional generation, perhaps with carbon sequestration, as we transition to a carbon-free electric grid over the next half century.” Swanson, Richard M. Photovoltaics Power Up, Science, 324, 891, 2009.

30. Renewable Energy and the NY Physics Standards • 4.1 Energy exists in many forms, and when these form change energy is conserved. • 4.1a All energy transfers are governed by the law of conservation of energy. • 4.1b Energy may be converted among mechanical, electromagnetic, nuclear, and thermal forms. • 4.1d Kinetic energy is the energy an object possesses by virtue of its motion. • 4.1e In an ideal mechanical system, the sum of the macroscopic kinetic and potential energies (mechanical energy) is constant. • 4.1f In a non-ideal mechanical system, as mechanical energy decreases there is a corresponding increase in other energies such as internal energy. • 4.1g When work is done on or by a system, there is a change in the total energy of the system. • 4.1h Work done against friction results in an increase in the internal energy of the system. • 4.1i Power is the time-rate at which work is done or energy is expended.

31. Continued… • 4.1j Energy may be stored in electric or magnetic fields. This energy may be transferred through conductors or space and may be converted to other forms of energy. • 4.1k Moving electric charges produce magnetic fields. The relative motion between a conductor and a magnetic field may produce a potential difference in the conductor. • 4.1l All materials display a range of conductivity. At constant temperature, common metallic conductors obey Ohm’s Law. • 4.1m The factors affecting resistance in a conductor are length, cross-sectional area, temperature, and resistivity. • 4.1n A circuit is a closed path in which a current can exist. • 4.1o Circuit components may be connected in series or in parallel. Schematic diagrams are used to represent circuits and circuit elements. • 4.1p Electrical power and energy can be determined for electric circuits.

32. Solar Wind 10 12 14 14 16 16 12 10 12 10 14 16 18 2 Megajoules/m 10 <10 12 10-12 12-14 14-16 16-18 20 18-20 22 24 14 26 20-22 6.0-6.5 m/s 13.4-14.6 mph 26 22-24 24 6.5-70 m/s 14 24-26 20 22 18 14.6-15.7 mph 16 26-28 >7.0 m/s >28 15.7+ mph Biomass Geothermal Agricultural resources & residues Wood resources & residues Agricultural & wood residues Low inventory o Temperature <90C o Temperature >90C Geopressured resources US Renewable Energy Assessment source: US IEA

33. Barriers to Change • US energy infrastructure is large • 400,000+ miles of gas and oil pipelines • 160,000+ of high voltage transmission lines • 176,000 gasoline stations • 1000’s of oil and gas wells drilled annually in the • Employment

34. Motivation for Change