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

Paint Your House White? SantoriniPaint Your House White? Santorini

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

U. S. Solar ResourcesU. S. Solar Resources

U. S. Tracking Mirror SolarU. S. Tracking Mirror Solar

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 Tea? Tibet, Dreprung MonasterySolar Tea? Tibet, Dreprung Monastery

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

How Hydropower WorksHow Hydropower Works

World-wide, about 20% of all electricity is World-wide, about 20% of all electricity is

generated by hydropowergenerated by hydropower..

Glen Canyon Dam and Power Station

Aswan Dam on the Nile River

Wind Power - MykonosWind Power - Mykonos

Clipper ShipClipper Ship

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.