population and ecosystems solar energy. aristarchus 270 bce, a scientific thinker from the island of...

Population and Ecosystems

Solar Energy

Solar Energy

Aristarchus 270 BCE, a scientific thinker from the island of Samos near Turkey, was the first to challenge Aristotle’s assertion that the earth was the center of the universe.

Our Sun, a modest star by astronomical accounting, is in state of nuclear turmoil in which 4.5 million tons of its mass “burn up” every second – that’s 140 trillion tons per year!

Solar Energy

The Sun is being converted into energy that streams out into space in all directions, mostly in the form of electromagnetic radiation of many wavelengths: X-rays, ultraviolet rays, visible light, infrared light, microwaves, and radio waves.

The Sun’s radiation provides just about all of the energy that drives life on Earth.

Solar EnergyStorage: Holds heat/coolness.

Solar Energy

Energy is the ability to do work – push, pull, turn, and change things. Light from the Sun that we can put to work is solar energy. The easiest way to capture se is to transform it into heat. When light strikes matter, it is either reflected or absorbed.

Solar Energy

In the home the greatest use of energy is for heating water and space. Both can be accomplished with passive solar applications, which capture and control the transfer of solar energy. Eventually heat from warm objects in the house will transfer to the air in the room, and the room will warm up too. This is solar space heating.

Solar Energy

Insulation slows the cooling of the room. It is a barrier between areas to two different temperatures. The most common insulation is dead-air space. Dead air, trapped and unable to circulate, is a poor conductor of heat energy. Most heat is lost through windows. So, if you double glaze the win or pull curtains over them, heat can’t escape as quickly because the sp bet the 2 panes of glass and bet cur and win is d-a sp.

Solar Energy

Another way to maintain space heat after sunset is to capture solar energy in a heat sink. A HS is like a heat sponge, soaking up heat during the day and releasing it at night. Some solar houses have massive brick walls oriented so that they receive direct sunshine for several hours a day.

Solar Energy

Large volumes of water in drums can serve the same purpose, because water is one of the most efficient materials on Earth for absorbing energy.

Solar water-heating technology uses metal plates called collectors. Dark ones (black) are absorbers, and white or silvery ones are reflectors. So the heat sink in a solar house will be painted black for maximum efficiency.

Solar Energy

When visible light hits the surface of the Earth, it is absorbed, and the water and soil of E warm up. Warm objects irrespective of how they got warm, reradiate or emit energy in the infrared wavelengths.

Solar Energy

Nearly all energy found in any form on the surface (crust) of Earth has been derived from solar radiation, except for nuclear.

Transfer of heat methods:Radiation: by means of electromagnetic waves.

Solar Energy



Conduction: passed through a material by molecular motion “touching”

Good Con: Metals (copper, iron, tin, aluminum)

Bad Con: glass, wood, ceramic, gasses (i.e. air)

Solar Energy



Conduction: passed through a material by molecular motion “touching”

Good Con: Metals (copper, iron, tin, aluminum)Bad Con: glass, wood, ceramic, gasses (i.e. air)

Convection: process by which a warm liquid or gas moves from one place to another.

Solar Energy

Advantages1. Available

anywhere on E.2. Inexhaustible

supply.3. Nonpolluting – no

air or water pol.4. Easily collected

w/portable devices.5. “Mining” is

environ-mentally safe.

Disadvantages1. Sunlight is a dilute

source of energy. Weak at any one point it must be collected.

2. Fluctuation in avail sunlight. Day/night; seasonal changes.

3. Thermal pollution. 4. Initial cost is high.

Solar Energy

Advantages6. No fuel refining

process, no toxic byproducts.

7. No transporting of fuels, no spills to contaminate land, rivers, oceans.

8. Requires no disposal of hazardous wastes.

Disadvantages5. Power plant is

unattractive.6. Need to meet

building codes.7. Need trained

people to install and maintain.

8. Question of legal right to access sunlight.

Solar Energy

Advantages9. Source of energy

itself is free.10.Source of energy

is not owned or monopolized.

11.Low maintenance costs.

12.Tax break in many states/countries.

Disadvantages9. Efficiency with

today’s devices approx 15 % while oil and coal approx 30 % to 40%.

Solar Energy

Early Uses of Solar Energy:1. Seasons, 2. Religion: Maya, Aztec, Stonehenge,

Egypt (Ra = Sun God), 3. Astronomy, 4. Greeks: Architectural designs

a. N Wall-1.5 ft thick to keep out winds,b. S Side-open courtyard – radiation

trapped in floor and adobe walls = solar storage.

Solar Energy

Early Uses of Solar Energy:1. Seasons, 2. Religion: Maya, Aztec, Stonehenge, Egypt (Ra = Sun God), 3. Astronomy,

4. Greeks: Architectural designs 5. Romans:

a. Oriented whole cities to sun, b. Invented window glass – improved solar

design – greenhouses, c. First laws protecting accessibility to buildings

to sunlight, d. First solar furnace.

Solar Energy

Early Uses of Solar Energy:1. Seasons, 2. Religion: Maya, Aztec, Stonehenge, Egypt (Ra = Sun God), 3. Astronomy,

4. Greeks: Architectural designs 5. Romans: 6. Solar ovens:

a. About 302 degrees F.b. Most inexpensive and reliable way to collect solar energy.

Solar Energy

Early Uses of Solar Energy:1. Seasons, 2. Religion: Maya, Aztec, Stonehenge, Egypt (Ra = Sun God), 3. Astronomy, 4. Greeks: Architectural designs 5. Romans: 6. Solar ovens:


7. Solar engines: a. Converts sunlight energy to

mechanical e,b. Late 1800s, c. Solar steam engine operating printing

press.

8. Solar Water Heating:

Solar Energy

Early Uses of Solar Energy:1. Seasons, 2. Religion: Maya, Aztec, Stonehenge, Egypt (Ra = Sun God), 3. Astronomy, 4. Greeks: Architectural designs 5. Romans: 6. Solar ovens:


7. Solar engines: a. Converts sunlight energy to mechanical e,b. Late 1800s, c. Solar steam engine operating printing press.

8. Solar Water Heating: a. Romans – bath water, b. 1891 – Clarence M. Kemp “Climax” a

metal black water tank; 32-700 gallons of water.

9. 20th Century:

Solar EnergyEarly Uses of Solar Energy:9. 20th Century:

a. 1955: First solar powered telephone call, b. Water pump, c. Solar engines – Sol en heats oil/water –

creates steam – turns turbines, d. Solar still – one of the most practical

applications: 1. Makes fresh water thru evaporation of salt

wat, 2. Salt left behind, 3. Fresh water collected, 4. Salt water evaporated at higher temperatures.

A bit less than half way finished. Take a 27 second

break. Vincent.

Solar EnergyMethods of collecting sunshine: basic

principal of collection is the greenhouse effect. Glass/plastic absorbs infrared rays and allows visual light to penetrate. Once inside some rays cannot pen/radiate back out; they are trapped inside the structure. There are direct and indirect methods for collecting sunshine.

Solar EnergyDirect Methods:1. Simplest, 2. Passive, 3. Demand high owner attention, 4. Sun’s rays penetrate directly into

house, 5. Home’s internal structure (concrete

floor, adobe walls, etc.) absorb heat generated (release when sun not shining),

Solar EnergyDirect Methods:6. Combine with insulated shutter to

keep heat from escaping at night, 7. Minimum of mechanical power

needed to distribute heat,8. Heat flows to rooms w/o help of ducts,

pumps, piping by thermal radiation.

Solar EnergyDirect Methods:A. Orientation of House,B. Shape of House,C. Color(s) of House,D. Windows/Openings of House, E. Use of Shading for House. NOTE: Some information/directions/

insulation/exterior plants may have to be reversed if your home is in the Southern Hemisphere.

Solar EnergyDirect Methods:A. Orientation of House: Principal Face

1. Insulation: a. Amount of sol en hitting a surface,b. Unit = “Langley,”c. Affected by length of day, clouds, humidity, elevation above sea level, obstacles.2. Need maximum ins on S + W side for winter, 3. Walls/windows absorb more during low sunned winter months.4. Roof rejects excess heat in high sunned summer.

Solar EnergyDirect Methods:B. Shape of House:

1. Square is not good anywhere, 2. Best is elongated E – W, 3. Having a second floor is good, 4. Having a basement can be an advantage.

Solar EnergyDirect Methods:C. Color(s) of House:

1. Dark colors absorb greater amount of sunlight than lighter colors,2. Winter exposure (low down) = dark colors due to sun level, 3. Summer exposure (high roof) = light colors due to sun level.

Solar EnergyDirect Methods:D. Windows/Opening of House:

1. Most significant factor = size + place-ment of W/O,2. Needs to be S placement, as it gives more hours of winter exposure because sun is lower level, 3. Needs to be clear glass (best) vs heat absorbing, reflective.

Solar EnergyDirect Methods:E. Use of Shading for House: Exterior:

Use of vegetation or movable shading:1. Place on S, SE, SW sides to minimize summer heat, 2. Awnings (simplest, flexible), 3. Veg/trellis (follows seasons less heat) deciduous trees/bushes, 4. Movable shading devices, 5. Vertical fins fencing.

Solar EnergyDirect Methods:E. Use of Shading for House: Interior:

1. Shading devices between panes of glass,2. Less effective, 3. Venetian blinds, draperies/curtains, roller shades.

Solar EnergyDirect Methods: Best:1. Four sides of house should not be

identical in appearance,2. Walls on N, E, and W are well

insulated, 3. Double clear glass windows on S,4. Dark colors: Low S and on N, E, W, 5. Light colors: high on S and roof, 6. Use of shading, 7. Build greenhouse on side of house

+/or window box collector.

Solar EnergyIndirect Methods: Overall: 1. Rely on mechanical power to move

heat,2. More complex, 3. More prone to failure, 4. Less owner attention.

Solar EnergyIndirect Methods: A. Basics, B. Flat-plate collectors, C. Concentrating collectors, D. Photovoltaic cells.

Solar EnergyIndirect Methods: A. Basics,

1. Rooftop solar collectors with separate heat storage devices, 2. Heat moves for collectors to storage using pumps/fans or,3. Heat moves indirectly to rooms using pipes/ducts.

Solar EnergyIndirect Methods: B. Flat-Plate Collectors Array:

1. Most commonly used, 2. One glass cover plate w/black abs- orber beneath, 3. Cover gl reduces loss of en thru front, 4. Ins behind abs re loss of en thru back,5. Heat in abs – fluid – carries off heat,6. Efficiency depends on orientation/tilt.

Solar EnergyIndirect Methods: C. Concentrating Collectors:

1. Concentrates sun’s rays to small area, converts to heat – fluid – steam – turbine.2. Produces high temperatures, 3. Requires mechanical devices to track sun across sky, 4. Initial cost of heliostat (mirrors), 5. Barstow, CA: Sol pwr tower, 1982, 1,800 mirrors, 250’ twr, en for 1,500 homes.

Solar EnergyIndirect Methods: D. Photovoltaic Cells:

1. Directly generates elect from sol en,2. PV Cell: Layered materials whose en activated by light, 3. No pollution, no noise, no moving parts, no use of water, 4. Minimal maintenance, 5. Stored in batteries,

Solar EnergyIndirect Methods: D. Photovoltaic Cells:

1. Directly generates elect from sol en,

2. PV Cell: Layered materials whose en activated by light, 3. No pollution, no noise, no moving parts, no use of water, 4. Minimal maintenance, 5. Stored in batteries,

6. Only convert 1/6 of sol en to elect.7. Trying to reduce costs.

Solar EnergyStorage: Holds heat/coolness.1. Active system = 15,000-20,000 gal tank.

a. Usually water = cheapest = holds large amts of heat.

b. Other mediums – paraffin, salt crystals, gravel.c. Tanks are expensive to replace.d. 6”-8” fiberglass ins needed to prevent heat loss.

2. Walls constructed of thick adobe, brick, concrete to prevent heat loss: absorbs heat in day = releases at night = wall is cool at night.

3. Directly hit by sunlight – walls, floors, air space: water and stone absorb more than straw and wood.

Solar EnergyStorage: Holds heat/coolness.1. Active system = 15,000-20,000 gal tank.2. Walls constructed of thick adobe, brick, concrete to prevent heat loss.3. Directly hit by sunlight – walls, floors, air space

4. Greenhouse w/insulation, window-box connector, sunroom.

5. Best = concrete wall w/insulation and sheathing on outside.

6. Below floor is most convenient: rock beds, salt water tanks (holds > heat than plain water).

Solar EnergyDistribute: move heat/coolness around.1. Use of vents: top = warm air out,

basement + crawlspace lets cool in, 2. Double door entry way: (“air lock”), 3. Open design of house with option of

closing areas – lets air circulate,4. Glass outside wall with vents at top,

bottom and floor5. Greenhouse/window-box collector on S

side.

Solar EnergyDistribute: move heat/coolness around.6. Pools of evaporating water on roof to

take heat away (liquid as gas takes energy),

7. Skylights with vents – open in summer to produce cross-ventilation = warm gets out top and pulls cooler in bottom. Closed in winter to heat inside air with sunlight.

Solar EnergyRetain: retards escape of heat/coolness.1. Insulation: adds resistance to walls,

floors, roofs (needed especially in roof and top 6inches of ceiling and N walls),

2. Windows w/shutters inside (removable) and outside,

3. Partially bury a wall (caves are consistent year round),

4. Triple paned windows and heavily caulked.

Solar EnergyRetain: retards escape of heat/coolness.5. Reduce loss of heat through window

cracks, door jambs, other openings, baseboards.a. Caulking,b. Weather stripping – best is metal, worst is spongy,c. Mortar joints, d. Tight-fitting windows and doors, e. Plant trees/bushes for wind protection,

Solar EnergyRetain: retards escape of heat/coolness.5. Reduce loss of heat through window cracks, door jambs, other openings,

baseboards.

f. Fixed windows vs operable windows,g. Double doors, h. Storm windows, i. Creating foyer or vestibule entrances, j. 4” x 6” wall studs,k. Create vapor barrier – high quality paints w/low permeability.

You now know what you need to know for your Solar Home Project. Now that wasn’t

too bad, or was it??? Vincent.

population and ecosystems solar energy. aristarchus 270 bce, a scientific thinker from the island of...

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