Presentation is loading. Please wait.

Presentation is loading. Please wait.

Solar FAQs and Global Renewable Energy Purpose of Solar FAQs document: Compile self-consistent set of supporting analyses and references Premise: The Sun.

Similar presentations


Presentation on theme: "Solar FAQs and Global Renewable Energy Purpose of Solar FAQs document: Compile self-consistent set of supporting analyses and references Premise: The Sun."— Presentation transcript:

1 Solar FAQs and Global Renewable Energy Purpose of Solar FAQs document: Compile self-consistent set of supporting analyses and references Premise: The Sun is a singular C-neutral solution to our future energy needs, one whose capacity dwarfs fossil, nuclear, wind, …

2 Overarching Assumptions 1.By 2050 we’ll need 15 TW, by TW, of new power –Ė = N · (GDP/N) · (Ė/GDP) –Even if N saturates and Ė/GDP continues to decrease, GDP/N will increase 2.All or most of this new power should be C-neutral –1-2 GtC/yr emissions (1940’s level) implies 550 ppmv atmospheric C and ΔT~2°C, and is already considered risky –6-7 GtC/yr emissions (2000’s level) is (perhaps nonlinearly) riskier 3.All of most of this new C-neutral power must be chemical –80% of energy consumed at point-of-use is chemical

3 Estimating Theoretical Potentials P fill (constant) p harvest (variable) E/  diss (variable) Steady State:P fill = E/  diss + p harvest No harvesting:P fill = E/  diss Max harvesting:P fill = p harvest 2.4 TW tidal friction 1-3 ms/century lengthening of the day ~ 0 TW human harvesting

4 Estimating Extractable & Technical Potentials Heat (TW t ) Electrical (TW e ) Chemical (TW c ) Mechanical (TW m ) Thermodynamic limit (1-T l /T h ) ~1/2 of Betz (16/27=59%) limit (33%) Theoretical Extractable Technical Chemical (TW c ) Fraction allowed by known technology 2010 EERE H 2 O electrolysis efficiency target (75%)

5 Table of Results

6 Solar 15 TW e = 0.17% of the earth’s surface (~ Venezuela) at 10% efficiency Average solar energy density W/m 2 40% Torrid % Temperate 150 8% Frigid 75 Average 175 Photons 89,000 TW p Electrical Chemical 58,000 TW c Chemical 61,000 TW c Chemical 19,000 TW c Heat Mechanical Electrical Theoretical Extractable Technical 2001 Actual Thermodynamic limit for un- concentrated sunlight (68%) Thermodynamic limit for concentrated sunlight (87%) 100% 33% Chemical 7,500 TW c Chemical 2,500 TW c Chemical 5,600 TW c Land only (29%) and Temperate+Torrid only (97%) Current best PV efficiency (40%/87%) Thermodynamic limit for concentrated sunlight (87%) Current photo-electrolysis efficiency (10%/68%) [Note: switchgrass efficiency is 0.38%] Current best steam engine efficiency (30%/28.7%) Chemical 0.15 GW c Chemical 190 GW c Chemical 0.6 GW c Tropic of Capricorn Tropic of Cancer Artic Circle Antarctic Circle 170,000 TW p 75% IEA PVPS 2004 (1/5 of peak capacity) WEA 2004 (sustainable only) WEA 2004 (active only) Nelson 2003 Fig 2.3

7 Wind Photons 110,000 TW p Electrical Chemical 250 TW c Mechanical 1,000 TW m Theoretical Extractable Technical 2001 Actual Thermodynamics 1-T l /T h (~0.84%) 33% Chemical 14 TW c Land only (29%) > Class 3 only (~20-27% x 2) Lateral replenishment from over oceans? Vertical replenishment from jet stream? Chemical 5 GW c Hodell and Thomas (U Florida atmospheric circulation website) ≥ Class 3 (~400 W/m 2 50m National Renewable Energy Laboratory 75% Heat 100% WEA 2004 Average wind energy density: 2 W/m 2 Wallace 1977 WEA 2000 Energy dissipation time ~ 8-9 days Cell circulation time ~ 2-5 days Wallace 1977

8 Ocean Waves Tropic of Capricorn Tropic of Cancer Artic Circle Antarctic Circle Electrical TW e Chemical 8.5 TW c Mechanical 34 TW m Theoretical Extractable Technical 2001 Actual Chemical 0.62 TW c Near-shore only (7%) Chemical ~0 GW c 33% 75% 1 m 20 knots 50 km 6 s 6 kW/m Average wave energy density in ice-free oceans: W m /m 2 WEA 2004 Wick 1977 Isaacs 1976 Wick 1977

9 Geothermal Heat 44 TW t Electrical TW e Chemical 2.8 TW c Mechanical TW m Theoretical Extractable Technical 2001 Actual Thermodynamic limit for ΔT~75°C (1-T l /T h ~ 25%) Chemical 1.9 TW c Land only (29% x 0.065/0.087) High-temperature (>150°C) only (?%) Thermodynamic limit for ΔT~150°C (50%/25%) Chemical 5 GW c ~2/3 Radiogenic ~1/3 Conduction through or cooling of lithosphere 75% 33% Average geothermal power density W/m 2 39% Land + Continental Shelves % Ocean Average IGA 2004 Lowrie IGA km thick lithosphere Mantle °C Outer core Inner core WEA 2004 (includes heat with conversion)

10 Summary Extractable Potential (TW c ) Technical Potential (TW c ) Solar Electricity Solar Fuel Solar Thermal Wind Ocean Wave Hydropower Geothermal Ocean Tidal Ocean Thermal Gradient Ocean Salinity Gradient Ocean Surface Currents Sources with > 15 TW extractable and technical potential 2001 Supply Extractable Potentials > 15 TW c : Solar, Wind, maybe Waves Technical Potentials > 15 TW: Solar, maybe Wind Theoretical Potentials > 15 TW c : Solar, Wind, Waves, Geothermal 2001 Actual > 15 TW: None even close


Download ppt "Solar FAQs and Global Renewable Energy Purpose of Solar FAQs document: Compile self-consistent set of supporting analyses and references Premise: The Sun."

Similar presentations


Ads by Google