H2 -­‐ + O2 Why Are We Going Here? •  NYS Science Key Idea 4: 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? U.S. Energy ConsumpSon Liquids Natural Gas Coal 45.000 Nuclear Hydropower 40.000 Renewable excluding Hydro Energy consump.on (quad BTU) 35.000 30.000 25.000 20.000 15.000 10.000 5.000 0.000 1980 1990 2000 2005 2010 2020 2030 World Energy ConsumpSon Sources of U.S. Energy U.S. Primary Energy Consumption by Source and Sector, 2007
(Quadrillion Btu)
1
Natural
2
Gas
23.6
70
24
96
2
2
3
34
34
30
44
37
9
3
Coal
22.8
9
8
<1
18
75
91
1
9
30
10
51
6
17
2
Renewable
4
Energy
6.8
Nuclear
Electric Power
8.4
Percent
of Sector
5 2
Petroleum
39.8
Percent
of Source
Transportation
29.0
Industrial
21.4
5
Residential
6
and Commercial
10.6
51
9
100
1
Does not include 0.6 quadrillion Btu of fuel ethanol, which is included in "Renewable Energy.”
2
Excludes supplemental gaseous fuels.
3
Includes less than 0.1 quadrillion Btu of coal coke net imports.
4
Conventional hydroelectric power, geothermal, solar/PV, wind, and biomass.
5
Includes industrial combined-heat-and-power (CHP) and industrial electricity-only plants.
21
Electric Power
7
40.6
6
Includes commercial combined-heat-and-power (CHP) and commercial electricity-only plants.
7
Electricity-only and combined-heat-and-power (CHP) plants whose primary business is to sell electricity,
or electricity and heat, to the public.
Note: Sum of components may not equal 100 percent due to independent rounding.
Sources: Energy Information Administration, Annual Energy Review 2007, Tables 1.3, 2.1b-2.1f and 10.3.
US EIA: www.eia.doe.gov The Energy Gap Local Emissions h]p://www.scorecard.org Delivering Energy ConflicSng Messages Point: A recent Wall Street Journal opinion editorial arScle 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.
“With Great Power Comes Great Responsibility…” -­‐-­‐Uncle Ben •  We efficiently consume ever-­‐increasing amounts of energy Energy Sources Sources Solar Energy fossil biogenic Coal Crude oil Natural gas Nuclear fusion biogenic Biomass photosynthesis Heat/light Wind Waves PrecipitaSon Streams Earth Crust fossil mineral Uranium Geothermal Nuclear fusion Planet Movement Tide Energy Carriers Energy Fluxes The Hydrogen Cycle Proposed to be abandoned by the DOE, not by Congress SyntheSc Hydrocarbons Fuel Cells Fuel Cell ApplicaSon Space Sta.onary (buildings) PAFC SOFC MCFC In space AFC PEM Portable electronics DMFC ~ -­‐10ºC >140ºC Fuel Used can vary with temperature (general rule of thumb) PEM SOFC PAFC Automo.ve DMFC Portable electronics SOFC II Automo.ve 600ºC ~1,000ºC complexity of fuel increasing increasing allowable contaminants in H2 require reformers, or very clean H2 can run on direct hydrocarbon fuels, or “dirty” H2 typical operaSng temperature Fuels and Equivalent Energy Density Wind •  The fastest growing technology among renewable resources •  Germany, Spain, the U.S., India, and Denmark are the top five wind installers (2005) No More Nukes? Green Chemistry, Manahan, S. E., 2005 The Nuclear Lifecycle Se]le, F. A. Journal of Chemical EducaNon, Vol. 86 No. 3 March 2009 DOE’s stance Geothermal Geography •  Sources and sites are limited –  No new discoveries Plants: Our best solar cells? Let nature do the work (we can take the credit) Corn-­‐per-­‐car area Pietro, W. J. Journal of Chemical EducaSon, Vol. 86 No. 5 May 2009 • •  A trip down the path to the first law of thermodynamics –  ReacSons at work in photosynthesis and fermentaSon Corn-­‐per-­‐car area Pietro, W. J. Journal of Chemical EducaSon, Vol. 86 No. 5 May 2009 • •  Sunlight power –  At 30-­‐45° laStude, photon density is 240 W/m2 –  Only 43% is photosyntheScally acSve = 103 W/m2 –  At best, farms can uSlize 80% of the area = 82 W/m2 •  Photosynthe.c 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 formaSon) of carbohydrate from CO2 and water is 528 kJ –  The overall photosyntheSc 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 Corn-­‐per-­‐car area (cont’d) •  FermentaSon chemistry –  The fermentaSon of carbohydrate to ethanol requires has a ΔG of -­‐278 kJ/mole –  18% of the original solar energy are used by yeast for fermentaSon, 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 Corn-­‐per-­‐car area (cont’d) •  Energy conversion –  82 W/m2 = 2.6 x 106 kJ/(year m2) –  MulSply by efficiency factors: –  Land requirements: –  This is equal to ~7,000 x2 per car –  Other consideraSons: Carbohydrates available for fermentaNon, actual duty cycle, fermentaNon efficiency, producNon overhead PV and Land Use Maximum Solar Cell Efficiencies 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 convenSonal generaSon, perhaps with carbon sequestraSon, as we transiSon to a carbon-­‐free electric grid over the next half century.” Swanson, Richard M. Photovoltaics Power Up, Science, 324, 891, 2009.
•
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 conservaSon of energy. 4.1b Energy may be converted among mechanical, electromagneSc, nuclear, and thermal forms. •
4.1d KineSc energy is the energy an object possesses by virtue of its moSon. •
4.1e In an ideal mechanical system, the sum of the macroscopic kineSc and potenSal 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 fricSon results in an increase in the internal energy of the system. •
4.1i Power is the Sme-­‐rate at which work is done or energy is expended. ConNnued… •  4.1j Energy may be stored in electric or magneSc 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 magneSc fields. The relaSve moSon between a conductor and a magneSc field may produce a potenSal difference in the conductor. •  4.1l All materials display a range of conducSvity. At constant temperature, common metallic conductors obey Ohm’s Law. •  4.1m The factors affecSng resistance in a conductor are length, cross-­‐
secSonal area, temperature, and resisSvity. •  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. SchemaSc diagrams are used to represent circuits and circuit elements. •  4.1p Electrical power and energy can be determined for electric circuits. US Renewable Energy Assessment 10
12
14
16
16
Solar 14
Wind 12
10
12
14
16
18
10
10
12
20
22 24
26
26
24
22 20 18
14
16
14
2
Megajoules/m
<10 10-­‐12 12-­‐14
14-­‐16
16-­‐18 18-­‐20
20-­‐22
22-­‐24 24-­‐26 26-­‐28 >28 Biomass 6.0-­‐6.5 m/s
13.4-­‐14.6 mph
6.5-­‐70 m/s
14.6-­‐15.7 mph
>7.0 m/s
15.7+ mph
Geothermal Agricultural resources & residues Wood resources & residues Agricultural & wood residues Low inventory o
Temperature <90C
Temperature >90C
Geopressured resources
o
source: US IEA 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 staSons 1000’s of oil and gas wells drilled annually in the Employment MoSvaSon for Change