Alternative Energy Sources
• 90% of the energy used today is
in the form of fossil fuels.
• Forms of energy OTHER than
fossil fuels are termed “alternative”
energy sources.
Alternative energy sources can be
divided into two main categories.
1) Renewable Energy Sources
• geothermal
• Solar
• Wind
• Ocean
• Water
• Biomass
2) Non-renewable energy sources
• nuclear power
Geothermal Energy:
heat energy from the Earth
- the conversion of natural heat from the Earth’s interior to
heat buildings and generate electricity.
- considered a non-renewable source when extraction
rates are greater than supply.
High vs. Low temp Geothermal
Low Temp: Use of groundwater, which is 55 F year round.
- Deep wells (over 100 feet) are dug, and groundwater is
used as a heat source in winter, and as a coolant in
summer.
- Initial costs are higher, but cost to run is much lower,
and uses little fuel.
High Temp. Geothermal
using hot water from the Earth as an energy
source.
- uses water heated from features
such as geysers and volcanoes
- direct heating of buildings, as well
as electricity generation.
- steam generated within volcanic
areas is used to turn turbines,
which generate electricity.
Outlook: Limited, because areas with enough
volcanic activity are not widespread. Great success
in areas where geothermal activity is high
(Iceland, California)
People bathing in Blue Lagoon near
Grindavik, Iceland
Solar Energy
The amount of incoming solar energy is immense.
- in 10 weeks, the amount of incoming solar energy would
equal the energy of all known fossil fuel reserves.
-Distribution is variable, due to climate, location on Earth,
etc…
Passive vs. Active Solar Energy
-Passive solar energy collection most often involves
the design of buildings, etc., to maximize the collection
of Suns energy. No energy is spent.
-Orientation of building to face south
-Glass walls to collect sunlight
-“Thermal Mass” to hold warmth
(brick/stone walls, beds of stone)
Active solar collection requires energy
to run pumps for circulation of water or
air, or to move collectors orientation to
follow the sun.
-water/air filled solar panels, with pumps to move heat to
where it is needed.
-The Luz Solar Electric generation system uses heated
oil to generate steam, which then generates electricity in
a turbine. Located in the Mojave Desert, U.S.
The Luz Solar Electric Generation System
Photovoltaic Solar:
Electricity is created directly from special solar
panels.
Hydrogen Power:
Hydrogen has the potential to be the largest energy
source of all.
Clean Burning (only water as exhaust!)
Inexhaustible supply, which is recycled
No fancy new drilling technology needed!
Ways to create Hydrogen Gas
1) Electrolysis: breaking water into Hydrogen and
Oxygen using electricity.
-uses lots of power to accomplish
-if harnessed to solar geothermal or wind power,
the Hydrogen could be free.(Iceland is banking on it!)
2) Stripping Methane of Hydrogen: using steam to
remove the 4 hydrogen atoms from CH4.
-still uses a fossil fuel, and releases Carbon
Dioxide gas in the process.
Water Power
Hydro-power is a good alternative energy
source, because it is essentially unlimited.
- Direct hydro-power: using moving water to turn
machinery, such as a mill.
- Hydro-electric power: using the power of
water to turn an electric generator, such as in a
dam.
Hydroelectric Power Generation
Power is generated
by harnessing the
energy of falling
water.
The greater the
difference in water
level, the more
energy
Outlook for Hydropower?
The outlook is generally good for
hydro-power, although there are a few
drawbacks.
Dams prevent the migration of fish, and also
prevent the natural flows of rivers, causing
sedimentation behind the dam and
displacement and/or disruption of the natural
habitat and its inhabitants.
Tidal/Current Power
generation of electricity from movement of
ocean tides or currents.
- Rising tides are trapped behind a dam, then released
to turn a generator.
- Also some work on ocean buoys that harness the
movement of water to generate electricity.
Outlook: Generally good, but tidal energy can only
be used in areas where tides are of sufficient height
to warrant an electrical station. High costs may be
associated.
Wind Power
generation of electricity using wind to turn
turbines.
Free energy, but needs to be in an area that has
constant winds with enough velocity to warrant placing
windmills.
Best used in particular sites with a good steady supply of
wind.
Outlook: Wind power will continue to grow, but in
limited areas. Some disadvantages and concerns
exist.
Windmills kill birds, and interfere with
migratory patterns.
Large windmill farms take up large areas of land.
Windmills also produce noise, which may be
objectionable.
Biomass Energy
energy from organic matter
Probably the first source of energy for man, this energy is
renewable and abundant.
Already in use in many places, such as sugar plantations
and saw mills.
Also includes the burning of urban waste, in “trash to
steam” plants.
Outlook: Biomass fuel will continue to be a
large part of the alternative energy picture.
However:
Environmental degradation can and will occur if the
biomass is not harvested in a renewable manner.
Burning biomass causes pollution, especially air pollution,
and leaves ash behind. The ash can be very toxic.
Carbon Neutral?
Will the energy future include
fossil fuels?
-There are a few “new” sources of fossil
fuels which may play a role in the future.
-They are still NON-RENEWABLE.
-They still cause pollution (in varying
amounts)
But there is a potential for LOTS of energy!
Non-Renewable: Nuclear Energy
This creates a CONTROLLED chain reaction in
a reactor
Benefits:
• Extremely efficient and effective
• No pollution
• Inexpensive after initial setup
Disadvantages
• Set up costs
• Waste disposal
• Safety
• Potential meltdown (ex, Chernobyl, Three Mile
Island)
Other Fossil Fuel prospects:
Oil Shale and Tar Sands
Deposits of sedimentary rock containing
significant amounts of petroleum.
Oil Shale: yields as high as 14 gal per ton of rock,
3 trillion barrels total (2/3 of which are in the U.S.)
Tar Sands: Known reserves in Canada of 2 trillion
barrels.
Problems with Oil Shale and Tar Sands
Both require extensive mining operations to be carried
out. Some in protected areas.
Disposal of mine tailings/overburden (20-30%larger in
volume than original rock.)
Possibility of acid mine drainage and runoff
Outlook: uncertain, at least until other possibilities
are explored, and prices enable mining and
proper reclamation of mined areas.
Methane Hydrates
White, ice-like compound consisting of
Methane (CH4) and water.
A potential source of energy, as large as
twice the known reserves of gas, oil, and
coal COMBINED.
Found in very deep ocean sediments (over
1000 feet in depth)
Outlook:
Drilling technology has not caught up, and
until it does, it is not possible to drill.
Methods to capture and transport the gas
will be necessary.
Higher gas prices will be needed to support
the large expense of exploration and drilling
The Future of Alternative Energy
Alternative energy sources will play larger roles in the
future, but each needs to be utilized in a manner which
damages the environment as little as possible.
Energy sources will need to be mixed, to use them to
their maximum potential.