Unit Five – Lesson 3 Alternative Energy Sources for Agriculture As Fossil Fuel sources are...
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Transcript of Unit Five – Lesson 3 Alternative Energy Sources for Agriculture As Fossil Fuel sources are...
Unit Five – Lesson 3
Alternative Energy Sources for Agriculture
As Fossil Fuel sources are depleted, new energy sources will be in greater demand
Sources being promoted are: Solar Hydroelectric Tidal Wind Biomass Fuels Geothermal energy Nuclear
Solar Energy
Energy from the Sun is absorbed by the Earth and used as a fuel by virtually all organisms.
Image courtesy of NASA
Solar Energy – many uses
Drives the Water Cycle. Energy for Photosynthesis. Thermal Energy can be used for heating and
electricity. Stored in Plants … eventually forming fossil
fuels.
Solar Energy – Two types
Passive Sun’s energy is collected, stored, and distributed
within a dwelling, such as heating a home.
Simplest and cheapest solar energy form.
Examples for Agriculture: Drying of crops in the field Curing of various other Ag products
Solar Energy – Two Types
Active Uses devices to collect, store and circulate heat
produced from collectors. Used in areas that receive maximum sunlight. Can be used to heat water (in tubes), the water
then can be used as hot water, or as a source of heating heat for a building.
Solar Energy and Electricity
Photovoltaic cells, known as solar cells, produce electricity by transferring electrons from a positive plate to a negative plate.
Used mainly to produce power for homes, industry and space applications.
Lightweight and long-lasting. Agricultural uses include greenhouses, livestock
buildings, and as a hot water source. Electric fences, lighting, pumps, and irrigation can
also be run on photovoltaic systems.
Advantages of Solar Energy
Free and unlimited Clean Non-polluting Renewable resource Low maintenance Little noise and machinery involved
Disadvantages of Solar Energy
Not a constant source (clouds, rain).
Upfront equipment cost is high.
Note: over time, the expenses involved can often be recovered through savings in energy costs
Hydroelectric Power
Energy produced form the kinetic energy of moving water. Very old process, used in a diversified manner. In 1925, 40% of the world’s electricity was
generated by flowing water. It supplies about 24% of the world’s electricity
(2007) … generating the same amount of energy annually as 36 million barrels of oil.
Necessitates the building of a large dam across a waterway, creating a deep reservoir.
Water is directed through the dam with enough force to turn large turbine blades.
The turbines spin within a magnetic field, producing electricity.
Hydroelectric Power
Photo courtesy of UN Atlas of the Oceans
Advantages of Hydroelectric Power
Flood control. Unlimited power. Non-polluting. Creates recreation areas. Stores water for irrigation purposes.
Photo courtesy of YTEP
Disadvantages of Hydroelectric Power
Alters the natural animal and plant life of an area. Water is colder on the upside of a dam.
Fish are unable to swim upstream, interfering with reproduction.
Erosion problems are created on the down-side of the dam from water not replenishing the soil with nutrients.
Tidal Energy
Works similarly to hydroelectric power, using turbines.
Water is captured in a reservoir during high tide, then released during low tide.
A difference of 16 feet is needed between tides.
Wind Energy
Generated by large wind generators with rotating blades.
Has been in use for power since the 1870’s. Windmills, previously used for pumping water
and grinding grains, were converted to produce electricity long ago.
Today, modern aero generators are used.
Aero Generators: Two Types
Horizontal type Airplane-shaped propellers used in areas where
15mph winds and higher are prevalent.
Vertical type Blades are shaped similarly to an egg-beater, able
to be used at lower wind speeds.
Advantages of Wind Energy
Free and unlimited source. Non-polluting. Source of income for farmers on land without
interfering with livestock and crops. Can be used to pump water (irrigation).
Disadvantages of Wind Energy
Requires a large land area. Set-up is expensive and dangerous. May take up to 15 years for a wind turbine to
pay for itself.
Future of Wind Energy
As of 2007, there were 32 states producing wind energy.
Represents 1% of total energy produced in the US, and can “save” 28 million tons of CO2
Since 1980, the cost of wind energy equipment has decreased by 90%.
Biomass Fuels
Fuels formed from living or recently living organisms, including forest, agriculture, and food processing wastes.
Are renewable source of energy (also called biofuels)
Energy is released by burning, providing heat or chemicals or other fuels.
Biomass Fuels and Sewage
Sewage treatment facilities use bacterial digestion to treat water, releasing methane gas (natural gas). Methane is a valuable fuel used in heating. Grain crops can be used for ethanol production, a
type of alcohol used as a fuel. Oil-bearing plants (soybeans, algae, etc.) possess
chemicals similar to diesel.
Ethanol
Alcohol-based fuel. Made from corn, sugar, barley, wheat, and other
grains. Lower fuel efficiency than gasoline. Reduces harmful emissions compared to gasoline. E-10 is 10% ethanol and 90% gasoline for all
gasoline-powered vehicles. E-85 is 85% ethanol and 15% gas, used in “flex-
fuel” vehicles only.
Biodiesel
Made from vegetable oils ,animal fats, or recycled restaurant greases.
B20 is 20% bio-diesel and 80% petroleum diesel, can be used in most vehicles with minor modifications.
Can be produced domestically. Biodegradable product
Advantages of Bio-fuels
Renewable resource that reduces greenhouse gases.
Increase economic growth. Increase agricultural employment.
Disadvantages of Bio-fuels
May decrease plant diversity. May cause food prices to increase, due to grain
compatibility as a fuel. Additional land is required to produce large
amounts. Emits Nitrogen Oxides (acid rain) Must be transported by truck or rail. Does not flow well at low temperatures. May not be compatible with seals and gaskets in
older vehicles.
Geothermal Energy
Heat energy created within the Earth through the decay of radioactive elements.
Heat is enough to melt solid rock (magma). Areas where it can be used is limited to the
edges of tectonic plates and volcanoes. Water that comes in contact with the hot
earth produces hot springs and geysers. Steam can be collected and used to spin turbines,
producing electricity.
Advantages of Geothermal Energy
Able to heat greenhouses. Able to dry out meat products. Heat water for aquatic farms. Heat and cool homes (heat transfer units).
De-ice roadways. Successful in other countries (Ireland gets 50% of
it’s energy from this source).
Disadvantages of Geothermal Energy
Emits hydrogen sulfide gas (toxic). Produces excessive salt and mineral buildup
in pipes. Lack of adequate water to produce steam in
some areas. Areas where enough water and heat are
present represent only 10% of the Earth’s surface.
Nuclear Energy
Energy released from the controlled splitting of atoms (fission), producing heat.
Heat is used to produce steam, which in turn, powers large turbines that produce electricity.
As of 2006, 19% of the electricity produced in the US was nuclear.
Uranium is mined to use in producing fuel rods that undergo fission.
Nuclear plants are called “reactors” …there are two types:
Burner reactors Large rods made of Uranium 235 (called the
“core”) produce immense heat while submerged in water.
Other rods are (made from energy-absorbing materials) are lowered into the core to keep the reaction from getting too hot.
Breeder reactors Uranium 238 is used to produce Plutonium 239,
which is then used to power the core.
Nuclear Energy
Advantages of Nuclear Power
Large amount of energy is available. Could potentially reduce the reliance on fossil
fuels and foreign oil. Does not produce greenhouse gases, smoke,
or ash.
Disadvantages of Nuclear Power Mining uranium is not a clean process, and it
will eventually run out. Cooling towers at nuclear power plants
produce heated water and steam, that is returned to the environment – resulting in “thermal pollution” which alters existing wildlife ecosystems.
Breeder reactors could be used to produce weapons.
Nuclear plants do produce dangerous wastes that are problematic to store and dispose.
Thermal Depolymerization
Process was invented in the mid 1990’s. Uses heat (steam) and pressure to convert existing
trash into short-chain hydrocarbons, used as fuels. During the process, all disease-producing
organisms are destroyed. In 2003 a full-scale plant went into operation in
Carthage, Missouri, more are being constructed. Source: http://www.thermaldepolymerization.org/