Post on 14-Dec-2015
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Power from the Sun:Power from the Sun:Solar, Hydro and WindSolar, Hydro and Wind
Dennis SilvermanDennis Silverman
U. C. IrvineU. C. Irvine
Physics and AstronomyPhysics and Astronomy
Solar PowerSolar Power
Most of all energy we use comes or has Most of all energy we use comes or has come from the sun.come from the sun.
Fossil fuels arise from fossil plants and Fossil fuels arise from fossil plants and animals converted to carbon (coal), or animals converted to carbon (coal), or hydrocarbons (methane and petroleum).hydrocarbons (methane and petroleum).
We are 1/3 to 1/2 through the process of We are 1/3 to 1/2 through the process of burning hundreds of millions of years of burning hundreds of millions of years of fossil fuel accumulations in two centuries.fossil fuel accumulations in two centuries.
Free SolarFree Solar
The sun would heat the planet to 0The sun would heat the planet to 0° Fahrenheit without ° Fahrenheit without the atmosphere.the atmosphere.The sun runs the greenhouse that keeps the earth The sun runs the greenhouse that keeps the earth warmed up to an average of 58warmed up to an average of 58° F° F with the greenhouse with the greenhouse gas atmosphere.gas atmosphere.It evaporates the oceans to provide the rain and fresh It evaporates the oceans to provide the rain and fresh water for crops and drinking water and hydropower.water for crops and drinking water and hydropower.It powers the weather to provide winds.It powers the weather to provide winds.It grows our crops and forests through photosynthesisIt grows our crops and forests through photosynthesisSolar energy provides our daylight and moonlight.Solar energy provides our daylight and moonlight.It heats our buildings in the daytime, and the sea and It heats our buildings in the daytime, and the sea and land hold heat for the night.land hold heat for the night.
Pharoah Akhenaten and Queen NefertitiPharoah Akhenaten and Queen NefertitiMonotheism of Aten, the Sun, 1353-1336 BC Monotheism of Aten, the Sun, 1353-1336 BC
Possible father of Tutankhamen (King Tut)Possible father of Tutankhamen (King Tut)
Solar ManipulationSolar Manipulation
The next best way to use solar is to modify The next best way to use solar is to modify its effects.its effects.– Reflective roofs to keep buildings coolReflective roofs to keep buildings cool– Reflective windows to keep out direct sunlight Reflective windows to keep out direct sunlight
during the summer, and keep heat in during during the summer, and keep heat in during the winterthe winter
– Windows and skylights for indoor daytime Windows and skylights for indoor daytime lightinglighting
Direct Solar EnergyDirect Solar Energy
Mediterranean climates now using rooftop Mediterranean climates now using rooftop or nearby solar water heating – Greece, or nearby solar water heating – Greece, Israel, Japan. It is 80% efficient.Israel, Japan. It is 80% efficient.
Solar clothes dryingSolar clothes drying
Solar Photovoltaic ElectricitySolar Photovoltaic Electricity
Silicon wafers doped to form photovoltaic cellsSilicon wafers doped to form photovoltaic cells– Power is free, butPower is free, but– Large wafers still thick and crystal grown as chips, so still Large wafers still thick and crystal grown as chips, so still
expensiveexpensive– Cost still 3 to 10 times as expensive as fossil fuel powerCost still 3 to 10 times as expensive as fossil fuel power– Efficiency only 10 to 15%, so large areas neededEfficiency only 10 to 15%, so large areas needed– Daily and yearly average only 1/5 of maximum power capacity Daily and yearly average only 1/5 of maximum power capacity
installedinstalled– Don’t need storage if send excess power back over the gridDon’t need storage if send excess power back over the grid– Storage could be in charging car batteries or in hydrogen fuel, orStorage could be in charging car batteries or in hydrogen fuel, or– Concentrate on using more energy during the daytimeConcentrate on using more energy during the daytime– Silicon valley investigating thin film disk technology to make Silicon valley investigating thin film disk technology to make
cheapercheaper
Unelectrified AreasUnelectrified Areas
Two billion people do not have electricityTwo billion people do not have electricity
To save on kerosene lanterns, solar cells To save on kerosene lanterns, solar cells with batteries and lcd lights have been with batteries and lcd lights have been developed for nighttime lightingdeveloped for nighttime lighting
Also used to charge freeway phonesAlso used to charge freeway phones
California’s Million Solar RoofsCalifornia’s Million Solar RoofsCalifornia SB1 (Senate Bill 1) to provide rebates to equip solar California SB1 (Senate Bill 1) to provide rebates to equip solar power installationspower installationsGoal is 3 gigawatts solar by 2017Goal is 3 gigawatts solar by 2017This could be 3 kw/household, at $9/watt is $27,000/householdThis could be 3 kw/household, at $9/watt is $27,000/householdCompanies rebated per kwh generatedCompanies rebated per kwh generatedNew homes must offer solar option by 2011New homes must offer solar option by 2011500,000 more homes can be added to generating electricity into the 500,000 more homes can be added to generating electricity into the power networkpower network$2.8 billion CA cost, 30% Federal rebate, up to $18 billion total cost, $2.8 billion CA cost, 30% Federal rebate, up to $18 billion total cost, but for less average electricity than a nuclear plant at $2-3 billion.but for less average electricity than a nuclear plant at $2-3 billion.Could only nearly pay if it brings down costs through economies of Could only nearly pay if it brings down costs through economies of scale, scale, or if it leads to technological breakthrough through research and or if it leads to technological breakthrough through research and competitioncompetitionOnly $100 million for solar water heatingOnly $100 million for solar water heating
Solar Trough MirrorsSolar Trough Mirrors
Suitable For Large Suitable For Large SystemsSystems Grid-connected Grid-connected PowerPower30-200 MW size30-200 MW sizeHeats mineral oil to Heats mineral oil to hundreds of degreeshundreds of degreesThen vaporizes a fluid Then vaporizes a fluid to drive a turbineto drive a turbine
Dish with Sterling EngineDish with Sterling Engine
ModularModular
Remote ApplicationsRemote Applications
Demonstration Demonstration InstallationsInstallations
High EfficiencyHigh Efficiency
Conventional Conventional ConstructionConstruction
Heat expands gas Heat expands gas and drives pistonand drives piston
Solar TowerSolar Tower
Suitable For Large Suitable For Large SystemsSystems
Grid-connected PowerGrid-connected Power
30-200 MW size30-200 MW size
Potentially Lower CostPotentially Lower Cost
Potentially Efficient Potentially Efficient Thermal StorageThermal Storage
Molten Salt heated, Molten Salt heated, averages out solar inputaverages out solar input
Can store heat overnightCan store heat overnight
Cost Of Energy*Cost Of Energy*(Max Lechtman)(Max Lechtman)
TroughTrough Dish/EngineDish/Engine TowerTower
20002000 11.811.8 17.9 17.9 13.613.620102010 7.6 7.6 6.1 6.1 5.2 5.220202020 7.2 7.2 5.5 5.5 4.2 4.220302030 6.8 6.8 5.2 5.2 4.2 4.2
*Cents/kWh in 1997 $*Cents/kWh in 1997 $
HydropowerHydropower
Of the renewable energy sources that generate Of the renewable energy sources that generate electricity, hydropower is the most often used. It electricity, hydropower is the most often used. It accounted for 7 percent of total U.S. electricity accounted for 7 percent of total U.S. electricity generation and 75 percent of generation from generation and 75 percent of generation from renewables in 2004renewables in 2004
Over one-half of the total U.S. hydroelectric Over one-half of the total U.S. hydroelectric capacity for electricity generation is concentrated capacity for electricity generation is concentrated in three States (Washington, California and in three States (Washington, California and Oregon) with approximately 27 percent in Oregon) with approximately 27 percent in Washington, the location of the Nation’s largest Washington, the location of the Nation’s largest hydroelectric facility – the Grand Coulee Damhydroelectric facility – the Grand Coulee Dam
World-wide, about 20% of all electricity is World-wide, about 20% of all electricity is
generated by hydropowergenerated by hydropower..
World Wind Capacity. Total now 74 Gigawatts worldwide, with 65% in Europe. Market growing at 32% a year. 3.3% of European electricity now from wind. 1% of U.S. electricity.
Wind Generation Physics
Power proportional to the cube of the wind velocity. (v² from Bernoulli pressure for force on wingshaped
propeller, times a distance per second of rotating propeller, which is proportional to v.)
Most of energy from small bursts. ½ of energy comes in 15% of the time. Average capacity factor is 35% of the maximum. Wind turbines best spaced 3-5 times the rotor diameter
perpendicular to the wind, and 5-10 times the diameter parallel to the wind.
Virginia’s “Switzerland” Wind Power Proposal
39 towers of 400 feet height $2 million per tower at 1 megawatt
So about a 40 megawatt peak project
Enough power for 15,000 homes x 12,000 kwh/yr / 9,000 hours/year = 20 million watts average Implies a 50% duty cycle
To compare to a 1 gigawatt nuclear plant, would require 50 such projects, or about 2,000 wind towers and $2 billion.
England, Germany, Netherlands:10 Gigawatt Foundation Project
Proposal for 2,000 wind turbines of 5 megawatts each to make 10 gigawatts
Could power more than 8 million homes Would cover 3,000 square kilometers In the southern North Sea
“Here Comes The Sun” (by George Harrison) Conclusions
“All renewable energy is local” Adapt to locally available sources of renewable energy
Energy conservation is still the cheapest form of making energy available
In California, solar water heating is the next cheapest source of energy
Hydro should be maintained Solar arrays are efficient and should be supported Wind power is about the cost of nuclear. Have to find the
right location. Siting a problem with views, noise, birds. Nuclear power is omitted from renewable, but should be
included as it also is non-polluting for greenhouse gases. Solar photovoltaic needs more research and
improvement, and is currently a wasteful investment.