Transcript Renewable Energy - Ms. Farley's Science Class

Renewable Energy
Section 1- Renewable
Energy Today
Renewable Energy
• Energy from
sources
constantly being
formed
• Use needs to be
increased
Solar Power
• Sun
• Passive Solar
Heating
– Uses heat from
sun directly
– Large windows
face directly
into sun
– N. hemispheresouth windows
Solar Power
• Active Solar
Heating
– Gathered by
collectors
– Usually mounted
on roof
– Heats water in
collector and
transfers
throughout home
Solar Power
• Photovoltaic Cellssolar cells
– Use sun energy to
produce a small
amt. of electricity
– Can be stored in
batteries
– Efficient and less
expensive
– Good for
developing
countries
Wind Power- Cheap and
Abundant
• Uneven heating from sun causes
wind
• Wind turbines can convert into
electricity
• Cheap
• Wind Farms- Large arrays of wind
turbines
• Problem transporting electricity from
rural to urban areas
Wind Farm
Biomass- Power from
Living Things
• Biomass fuel- any
organic matter
used for energy
– Ex: Wood, organic
trash and manure
– Burning can
release air
pollution
– Methane gas from
decomposition
Biomass- Power from
Living Things
• Alcohol- Liquid fuel
derived from
biomass
– Ethanol- from
fermenting fruit or
agricultural waste;
corn is major
source
– Gasohol- gasoline +
ethanol
• Less air pollution
Hydroelectricity- Power
from Moving Water
•
•
•
•
20% of world’s electricity
Dams hold water- reservoir
Released to turn a turbine
Benefits:
–
–
–
–
Inexpensive
No air pollution
Last longer than power plants
Provide: flood control, drinking water,
agriculture, industry, and recreation
Hydroelectricity- Power
from Moving Water
• Disadvantages:
– Disruption of
ecosystems; Ex:
Salmon
– Displacement of
people
– Farmland below
dams less fertile
• Future:
• Micro-hydropowerFloating turbine in a
small stream
Geothermal EnergyPower from the Earth
• Energy from heat in the water
deposits of the earth’s crust
• Geothermal pumps- heated
water to turbine and recycle
back for reheating
– U.S. world’s largest producer
– Ex: The Geyser’s in CA-1.7 million
houses
Geothermal Energy
Geothermal Heat
Pumps- Energy for
Homes
• 600,000 homes in U.S.
• Stable underground
temperatures year-round allows
for heating and cooling all year
• Ground cooler in summer and
warmer in winter
Geothermal Heat Pump
Chapter 18- Renewable
Energy
Section 2- Alternative
Energy and Conservation
Alternative Energy
• Energy sources that do not use
fossil fuels and are still in
development
• Viable if cost effective and
environmental effects are
acceptable
• Research with gov’t investment
Tidal Power
• Tide- movement of
water caused by
gravitational b/w
sun, moon and
Earth
– Twice a day, rise
and fall
– Used to generate
electricity in France,
Russia and Canada
– France and Britain
used over 1000 yrs
ago
• High tides come in,
trapped by a dam
• After low tide, dam
opens to allow
water to rush out
spinning a turbine
to generate
electricity
• Cost is high to build
and maintain
• Few siutable
locations
Tidal Power
Ocean Thermal Energy
Conversion
• Warm surface water boils sea water
at low temp. in a vacuum
• Steam spins a turbine to generate
electricity
• Cold water from deep ocean cool
steam back into liquid to be used
again
• Not cost effective and effects of
pumping large amounts of cold water
to surface are unknown
Ocean Thermal Energy
Conversion
Hydrogen- A Future Fuel
Source?
• Most abundant element in universe
can be burned as fuel
• No carbon-no pollution!
• When burned combines with oxygen
to form water vapor and nitrogen
oxide
• Can split molecules of water or grow
plants to produce hydrogen cost
effectively
Challenge of Hydrogen
Fuel
• Takes a lot of energy to produce
• Use of fossil fuels to split atoms
pollutes
– Can use solar or wind power
– Can store in tanks and transport in
pipes
– Could use as it is produced in fuel
cells
Fuel Cells
• Produces
electricity
chemically by
combining H with O
• Can be fueled by
anything w/ large
amounts of H, such
as gasoline, natural
gas and alcohol
• Could continue to
use gasoline
stations
Energy Efficiency
• Percentage of energy put into a
system that does useful work
• Energy efficiency =
Energy Out X 100
Energy In
• First Law of
Thermodynamics- Energy in must
equal energy out; much lost as
heat
Energy Efficiency
• Over 40% of commercial energy is
wasted
– Fuel-wasting vehicles, furnaces, and
appliances
– Leaky, poorly insulated buildings
• Could save by:
– Fuel cells instead of internal combustion
engines
– Increase public transportation
– Fluorescent instead of incandescent
lights
Hybrid Cars
• Small, efficient gasoline engines with
also an electric motor for extra
power
• Convert braking energy into
electricity to store in battery
• Shut off gas engine to save fuel when
sitting
• Aerodynamics make less energy for
acceleration
• Cost a little bit more, but less to
refuel and pollute less
Hybrids
Cogeneration
• Production of two useful forms
of energy from same fuel source
– Ex: Waste heat from an industrial
furnace can run a steam turbine for
electricity
– Can supply heat and electricity to
multiple buildings
– Small units now available in U.S.
Energy ConservationSaving Energy
• Cities and Towns
– Plug leaks around
windows and doors
– Replace inefficient
furnaces
– Insulate water
heaters
– EX: Osage, Iowa
saved over $1
million a year;
boosted economy
• Around the
Home
– $1,200/year per
home; lost
energy through
poor insulation
– Seal doors and
windows
(replace w/high
efficiency
windows)
Save Energy Around the
Home
Conservation in Daily
Life
• Use less of any • Conservation Tips:
or ride a bike on
resource to save – Walk
short trips
energy
– Carpool or use public
transportation
• Wash clothes in
– Drive a fuel-efficient
cold water for
automobile
less energy
– Choose ENERGY
STAR* products
usage (25% of
– Recycle and buy
heat usage)
recycled products
– Set computers to sleep
mode when not in use