Transcript Document

Energy Efficiency and
Renewable Energy
Chapter 16
16-1 Why Is Energy Efficiency an
Important Energy Resource?
 Concept 16-1 We could save as much as 43% of all
the energy we use by improving energy efficiency.
We Waste Huge Amounts of Energy
 Energy conservation
• A decrease in energy use as a result of a decrease in
the amount of wasted energy – “Use less”
 Energy efficiency
• The measure of work we can get out of a unit of
energy we use – “Use it better”
 Four widely used devices waste large amounts of energy:
• Incandescent light bulb: 95% lost as heat
• Internal combustion engine: 94% of the energy from fuel wasted
• Nuclear power plant: 92% of energy is wasted through nuclear
fuel and energy needed for waste management
• Coal-burning power plant: 75-80% of the energy released by
burning coal is lost
Flow of Commercial Energy through
the U.S. Economy
 84% of all commercial
energy used in the
U.S. is wasted.
 41% wasted due to
the 2nd law of
thermodynamics.
 Only 9% of the total
energy put into the
U.S. economy results
in useful energy.
Advantages of Reducing
Unnecessary Energy Waste
16-2 How Can We Cut Energy Waste?
 Concept 16-2 We have a variety of technologies
for sharply increasing the energy efficiency of
industrial operations, motor vehicles, and buildings.
We Can Save Energy
and Money in Industry
 Industry accounts for 38% of U.S. energy
consumption. It can save energy and money by:
• Produce both heat and electricity from one energy source
(cogeneration or combined heat and power, CHP)
• Use more energy-efficient electric motors
• Recycle materials
• Switch from low-efficiency incandescent lighting to higherefficiency compact fluorescent (CFL) and LED lighting
• Update the old/wasteful electrical grid system (how electricity
is transmitted from the power plant to the consumer)
• Utility companies promote use of energy
• Instead, should promote conservation
We Can Save Energy and Money
in Transportation
 Transportation accounts for 2/3 of U.S. oil demand
and is a major source of air pollution.
 We can save energy in transportation by increasing
fuel efficiency and making vehicles from lighter and
stronger materials.
 Corporate Average Fuel Economy (CAFE) standards
• The average fuel economy, in miles per gallon (mpg), of a
manufacturer’s fleet of passenger cars and/or light trucks
 Fuel-efficient cars are on the market
 Tax breaks for buying fuel-efficient cars
Average Fuel Economy of New Vehicles Sold
in the U.S. and Other Countries
 CAFE standards did not increased from 1985 to 2009.
 In 2009, the Obama administration increased the standards
to 35.5 MPG by 2016.
 In 2012, the Obama administration increased the standards
again to 54.5 by 2025.
• This represents the doubling of the original CAFE standards
More Energy-Efficient Vehicles
Are on the Way
 Hybrid vehicles have two types of engines working
together to achieve higher gas mileage (15-70% more)
and lower engine exhaust emissions:
• A standard gas powered engine
• An electric motor assist powered by a rechargeable
nickel-metal hydride (NiMH) battery pack
 Gasoline-electric hybrid car
• Mostly gas…some electric
 Plug-in hybrid electric vehicle
• Mostly electric…some gas
 Electric vehicle (EV’s)
• ALL electric
Solutions: A Hybrid-Gasoline-Electric Engine
Car and a Plug-in Hybrid Car
More Energy-Efficient Vehicles
Are on the Way
 Hybrid cars accounted for 3.5% cars on the road in 2012.
• Up from than 1% in 2007
 Typically cost $3-4,000 more than non-hybrid models.
 Plug-in hybrids can get twice the mileage of gasolineelectric hybrid cars, but…
• How is the electricity generated?
• Electricity from coal or nuclear power plants = JUST AS BAD
• Electricity produced by wind or solar energy = GOOD
 Analysts estimate that hybrid cars could make up as
much as 20% of the car market by the year 2020.
• The boost in sales will be pushed by consumer demands
and possible government regulations on CO2 emissions.
Science Focus:
The Search for Better Batteries
 Current obstacles to hybrid or electric vehicles:
• Storage capacity of battery
• Currently about 100 mile range
• Charging time
• 8 hours for a Nissan Leaf (available NOW)
• 3 hours for a Ford Focus EV (available in 2013)
• Use of rare earth metals for battery construction
We Can Design Buildings
That Save Energy and Money
 Green architecture
• Makes use of passive solar heating, natural lighting, natural
ventilation, rain water collection, cogeneration of heat/electricity,
geothermal heat pumps, and recycled building materials
 Living or green roofs
 Superinsulation
 U.S. Green Building Council’s Leadership in Energy
and Environmental Design (LEED)
Graded on 100 possible points:
Certified - 40 - 49 points
Silver - 50 - 59 points
Gold - 60 - 79 points
Platinum - 80 points up
We Can Save Energy and Money
in Existing Buildings
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Insulate and plug leaks
Use energy-efficient windows
Stop other heating and cooling losses
Heat houses more efficiently
Heat water more efficiently
Use energy-efficient appliances
Use energy-efficient lighting
 About 1/3 of the heated
air in typical U.S. homes
and buildings escapes
through closed windows,
holes, and cracks.
Individuals Matter:
Ways in Which You Can Save Money Where You Live
Why Are We Still Wasting So Much Energy?
 Low-priced fossil fuels and few government tax
breaks or other financial incentives for saving
energy promote energy waste.
We Can Use Renewable Energy in Place of
Nonrenewable Energy Sources
 A variety of renewable-energy resources are
available but their use has been hindered by a
lack of government support (subsides) compared
to nonrenewable fossil fuels and nuclear power.
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Direct solar
Moving water
Wind
Geothermal
16-3 What Are the Advantages and
Disadvantages of Solar Energy?
 Concept 16-3 Passive and active solar heating
systems can heat water and buildings
effectively, and the costs of using direct sunlight
to produce high-temperature heat and electricity
are coming down.
Solar Power
We Can Heat Buildings and Water
with Solar Energy
 Passive solar heating system
• Absorbs/stores heat from the sun within a structure
without the need for pumps to distribute the heat.
• Lots of windows on the south side of house
We Can Heat Buildings and Water
with Solar Energy
 Active solar heating system
• Pumping a liquid such as water or an oil through
rooftop collectors
• Can also be used to provide hot water
Trade-Offs: Passive or Active Solar Heating
We Can Use Sunlight to Produce HighTemperature Heat and Electricity
 Solar thermal systems
• Sunlight is directed
towards a central
tower where and oil
absorbs the heat and
is used to create high
temperature steam to
turn a turbine.
 Large arrays of solar collectors in sunny deserts
 Costs are high and energy yield is low.
Solutions:
Woman in India Uses a Solar Cooker
 Solution to the “fuel wood crisis”?
We Can Use Solar Cells to Produce Electricity
 Photovoltaic (PV) cells (solar cells)
• Convert solar energy to electric energy
• Can be made in all shapes and sizes and can be included
in the building design and construction.
We Can Use Solar Cells to Produce Electricity
 Solar cells can be used
in rural villages with
ample sunlight who are
not connected to an
electrical grid.
• Mostly for pumping water
We Can Use Solar Cells to Produce Electricity
Gigawatts of solar generation
 Solar cells currently
account for less than 1%
of the world’s electricity
 Solar power has the
largest POTENTIAL for
supplying electrical power
to the world.
Projected growth of solar generation
Trade-Offs:
Solar Cells, Advantages and Disadvantages
 Photovoltaic cells
costs are high but
are quickly falling as
a result of mass
production, new
designs, and
nanotechnology.
16-4 Advantages and Disadvantages of
Producing Electricity from the Water Cycle
 Concept 16-4 Water flowing over dams, tidal
flows, and ocean waves can be used to generate
electricity, but environmental concerns and
limited availability of suitable sites may limit the
use of these energy resources.
Hydropower
We Can Produce Electricity from Falling
and Flowing Water
 Hydropower
• Build a high dam across a large river
• Water builds up into a reservoir
• Let water flow through large pipes and turn turbines
to produce electricity
 World’s leading renewable energy source used to
produce electricity
• 16% of the world’s electricity
• 99% in Norway, only 7% in the U.S.
We Can Produce Electricity from Falling
and Flowing Water
Trade-Offs: Large-Scale Hydropower,
Advantages and Disadvantages
Tides and Waves Can Be Used to
Produce Electricity
 Ocean tides and waves and temperature differences
between surface and bottom waters in tropical
waters are not expected to provide much of the
world’s electrical needs.
• Few suitable sites
• High costs
• Equipment corrosion
 Only two large tidal energy dams are currently
operating: one in La Rance, France and Nova
Scotia’s Bay of Fundy (where the tidal difference can
be as high as 63 feet).