RENEWABLE ENERGY – SOLAR. DIRECT SOLAR ENERGY Varies with latitude, season, time of day, and cloud cover.

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.