RENEWABLE ENERGY – SOLAR
DIRECT SOLAR ENERGY Varies with latitude, season, time of day, and cloud cover
HEATING BUILDINGS AND WATER Passive solar energy
system of putting the sun’s energy to use without requiring mechanical devices to distribute the collected heat
Certain design features can enhance passive solar energy’s heating potential South facing windows (in N. hemisphere) Well insulated buildings Attic vents Overhangs and solar sunspaces
HEATING BUILDINGS AND WATER Active Solar Energy
System of collecting and absorbing the sun’s energy, and using pumps or fans distribute the collected heat
• Most common• Series of collection
devices on roofs or in fields
• Typically a black panel or plate
• Used to heat water
SOLAR THERMAL ELECTRIC GENERATION
PHOTOVOLTAIC SOLAR CELLS Thin cells are treated with certain metals so that they generate electricity when they absorb solar energy • PROS:
• Convert sunlight directly into energy
• No pollution and minimal maintenance
• Used on any scale• Lighted road signs• Entire buildings
PHOTOVOLTAIC SOLAR CELLS Can be incorporated into building materials
Roofing shingles Tile Window glass
COST OF ELECTRICAL POWER PLANTS
INDIRECT SOLAR ENERGY
• Biomass• Plant materials used as fuel
• Ex: wood, crop wastes, sawdust, and animal wastes • Contains energy from sun via photosynthesizing plants
• Renewable when used no faster than it can be produced
• Can convert to biogas or liquids• Ethanol and methanol
BIOFUELS Energy comes from carbon fixation Bioethanol - from fermentation Biodiesel – from vegetable oils and animal fats
ADVANTAGES AND DISADVANTAGES OF
BIOMASS Advantages
Reduces dependence on fossil fuels Often uses waste materials If trees are planted at same rate biomass is combusted, no net
increase in atmospheric CO2
Disadvantages Requires land, water and energy Can lead to
Deforestation Desertification Soil erosion
INDIRECT SOLAR ENERGY Wind Energy Electric or mechanical energy obtained from surface air currents caused by solar warming of air
World’s fastest growing source of energy
Wind results from sun warming the atmosphere Varies in direction and magnitude
New wind turbines harness wind efficiently
WIND ENERGY
Cons:• Kills birds and bats• Can be costly • Public resistance
PROS:• Most profitable in rural areas with constant wind• Few environmental problems• No waste- clean source of energy
WARM UP 4/17/20151)What is significant about Yucca Mountain, Nevada?
2)What was the incident that occurred at Chernobyl, Ukraine and what was significant about it?
3)What is the difference between human use of passive solar energy and active solar energy?
4)What are two pros and two cons of using biomass as an energy source?
5)What are two pros and two cons of using wind as an energy source?
WARM UP 4/17/20151)What is significant about Yucca Mountain, Nevada?
2)What was the incident that occurred at Chernobyl, Ukraine and what was significant about it?
3)What is the difference between human use of passive solar energy and active solar energy?
4)What are two pros and two cons of using biomass as an energy source?
5)What are two pros and two cons of using wind as an energy source?
WARM UP 4/17/20151)What is significant about Yucca Mountain, Nevada?
2)What was the incident that occurred at Chernobyl, Ukraine and what was significant about it?
3)What is the difference between human use of passive solar energy and active solar energy?
4)What are two pros and two cons of using biomass as an energy source?
5)What are two pros and two cons of using wind as an energy source?
ADVANTAGES AND DISADVANTAGES OF
BIOMASS Advantages
Reduces dependence on fossil fuels Often uses waste materials If trees are planted at same rate biomass is combusted, no net
increase in atmospheric CO2
Disadvantages Requires land, water and energy Can lead to
Deforestation Desertification Soil erosion
WARM UP 4/17/20151)What is significant about Yucca Mountain, Nevada?
2)What was the incident that occurred at Chernobyl, Ukraine and what was significant about it?
3)What is the difference between human use of passive solar energy and active solar energy?
4)What are two pros and two cons of using biomass as an energy source?
5)What are two pros and two cons of using wind as an energy source?
WIND ENERGY
Cons:• Kills birds and bats• Can be costly • Public resistance
PROS:• Most profitable in rural areas with constant wind• Few environmental problems• No waste- clean source of energy
INDIRECT SOLAR ENERGYHydropower
Form of renewable energy reliant on flowing or falling water to generate mechanical energy or electricity
Sun’s energy drive hydrologic cycle
Most efficient energy source (90%)
HYDROPOWER Generates 19% of world’s energy Traditional hydropower – only for large dams New technology - May be able to utilize low flow waterways
Problems with Dams Changes natural flow of rivers Disrupts migratory fish patterns Potential dam breaks
OTHER RENEWABLE ENERGY SOURCES Geothermal Energy
Energy from the Earth’s interior for either space heating or generation of electricity
From Hydrothermal Reservoirs Created by volcanoes Reservoirs used directly for heat or to generate electricity
GEOTHERMAL ENERGY From hot, dry rock Geothermal heat pumps
Use difference in temperature between surface and subsurface
Great for heating buildings
Very Expensive installation
OTHER RENEWABLE ENERGY SOURCES Tidal Energy
Form of renewable energy that relies of the ebb and flow of the tides to generate electricity
Typical difference between high and low tide is 1-2 ft Narrow bays may have greater variation
Energy can be captured with A dam across the bay A turbine similar to a wind turbine
HYDROGEN FUEL CELL Fuel cell• Device that directly converts chemical energy into electricity
• Requires hydrogen from a tank and oxygen from the air
• Similar to a battery, only the reactants are supplied from outside source
DRAW THISKNOW THIS
https://www.youtube.com/watch?v=6UwSazq8GTU
https://www.youtube.com/watch?v=8rofx6Gaz40
HYDROGEN AS A FUEL SOURCE
Advantages to Hydrogen as a fuel source Very high energy density Can be produced from any electrical source Electrolysis (see illustration on next slide)
No greenhouse gases and few other pollutants
Can be used in vehicles Disadvantages to Hydrogen as a fuel source Highly volatile (requires special storage)
HYDROGEN AS A FUEL SOURCE-ELECTROLYSIS
SAVING ENERGY
Energy Efficiency and Energy Conservation
Energy efficiency the measure of the useful
energy produced by an energy conversion device compared to the energy that ends up being converted to low-quality (useless) heat
EFFICIENCIES
THE IMPORTANCE OF IMPROVING ENERGY EFFICIENCY
First Law of thermodynamics Energy cannot be created nor destroyed
Second Law of thermodynamics In most energy transformations, a significant fraction of energy is lost.
IMPORTANCE OF IMPROVING ENERGY EFFICIENCY
84% of all commercial energy produced in the U.S. is wasted!
Uranium100%
Electricity from Nuclear Power Plant
14%
Resistanceheating(100%)
90%
Wasteheat Passive Solar
Sunlight100%
Wasteheat
14%
Transmissionof electricity
(85%)
17%
Wasteheat
Power plant(31%)
54%
Wasteheat
Uranium processingand transportation
(57%)
95%
Wasteheat
Uraniummining(95%)
REDUCING ENERGY WASTE AND IMPROVING ENERGY EFFICIENCY Four widely used devices waste large amounts of energy: Incandescent light bulb: 95% is lost as heat. Internal combustion engine: 94% of the energy in its fuel is wasted.
Nuclear power plant: 92% of energy is wasted through nuclear fuel and energy needed for waste management.
Coal-burning power plant: 66% of the energy released by burning coal is lost.
COGENERATION
Production of two useful forms of energy from the same fuel
We can use fewer energy resources by becoming more energy efficient!
SAVING ENERGY IN EXISTING BUILDINGS
About one-third of the heated air in typical U.S. homes and buildings escapes through closed windows and holes and cracks.
WAYS TO IMPROVE ENERGY EFFICIENCY
In Our Homes• Insulation• High performance windows
• Energy Star appliances • Lighting
SAVING ENERGY AT HOME
STRAWBALE HOUSE
Strawbale is a superinsulator that is made from bales of low-cost straw covered with plaster or adobe. Depending on the thickness of the bales, its strength exceeds standard construction.
LIVING ROOFS Roofs covered with plants have been used for decades in Europe and Iceland.
These roofs are built from a blend of light-weight compost, mulch and sponge-like materials that hold water.
WAYS TO IMPROVE ENERGY EFFICIENCY
Industry•Cogeneration•Efficient electric motors•High efficiency lighting• Increased fuel economy
WAYS TO IMPROVE ENERGY EFFICIENCY
Transportation• Increase fuel efficiency of motor vehicles
• Less than 1% of car sales are fuel-efficient cars
WAYS TO IMPROVE ENERGY EFFICIENCY
Average fuel economy of new vehicles sold in the U.S. between 1975-2006.
The government Corporate Average Fuel Economy (CAFE) has not increased after 1985.
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