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 CO 2  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 4/17/2015 1) 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 4/17/2015 1) 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 4/17/2015 1) 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 CO 2  Disadvantages  Requires land, water and energy  Can lead to  Deforestation  Desertification  Soil erosion

WARM UP 4/17/2015 1) 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 ENERGY Hydropower  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 THIS KNOW THIS

 8GTU 8GTU  az40

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!

Uranium 100% Electricity from Nuclear Power Plant 14% Resistance heating (100%) 90% Waste heat Passive Solar Sunlight 100% Waste heat 14% Transmission of electricity (85%) 17% Waste heat Power plant (31%) 54% Waste heat Uranium processing and transportation (57%) 95% Waste heat Uranium mining (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  The government Corporate Average Fuel Economy (CAFE) has not increased after 1985.