Alternative Energy Sources
Alternative energy sources are resources that are constantly replaced
and are usually less polluting. They are not the result of the burning
of fossil fuels or splitting of atoms. The use of renewable energy
is contributing to our energy supply. Some alternative energy sources
are: biomass, geothermal, hydroelectric, solar, wind power, fuel
cells, ocean thermal energy conversion, tidal energy, and wave energy.
Biomass is renewable energy that is produced
from organic matter. Biomass fuels include wood and forest and mill
residues, animal waste, grains, agricultural crops, and aquatic
plants. These materials are used as fuel to heat water for steam
or processed into liquids and gases, which can be burned to do the
same thing. In Canada, biomass energy is used mainly in the forest industries.
Geothermal energy uses heat from within the earth.
Wells are drilled into geothermal reservoirs to bring the hot water
or steam to the surface. The steam then drives a turbine-generator
to generate electricity in geothermal plants. In some places this
heat is used directly to heat homes and greenhouses, or to provide
process heat for businesses or industries. Reykjavik, Iceland is
heated by geothermal energy. The famous hot springs in Banff, Alberta are an example of geothermal direct heat at a resort. Geothermal heat pumps
use shallow ground energy to heat and cool homes almost anywhere.
With technological improvements much more power could be generated
from hydrothermal resources. Scientists have been experimenting
by pumping water into the hot dry rock that is 5 to 10 km deep everywhere
below the earth’s surface for use in geothermal power plants.
Hydroelectric (hydropower) energy employs the
force of falling water to drive turbine-generators to produce electricity.
Hydropower produces more electricity than any other alternative
energy sources. In Canada, hydro power is the most popular form of electricity generation and accounts for nearly two-thirds of all electricity produced here.
Solar energy is generated without a turbine or
electromagnet. Special panels of photovoltaic cells capture light
from the sun and convert it directly into electricity. The electricity
is stored in a battery. Solar energy can also be used to directly
heat water for domestic use (solar thermal technology). Active solar energy (which uses rooftop photovoltaic collectors and focusing mirrors) currently accounts for only a tiny fraction of Canada's energy use, but some studies have indicated that it could meet as much as 5% of the country's energy needs by the year 2025.
Wind energy can be used to produce electricity.
As wind passes through the blades of a windmill, the blades spin.
The shaft that is attached to the blades turns and powers a pump
or turns a generator to produce electricity. Electricity is then
stored in batteries. The speed of the wind and the size of the blades
determine how much energy can be produced. Wind energy is more efficient
in windier parts of the country. Most wind power is produced from
wind farms—large groups of turbines located in consistently
windy locations. Wind, used as a fuel, is free and non-polluting
and produces no emissions or chemical wastes. Wind-powered electricity
is gaining in popularity.
Fuel cells are electrochemical devices that produce
electricity through a chemical reaction. Fuel cells are rechargeable,
contain no moving parts, are clean, and produce no noise. Scientists
are exploring ways that they could be used as a power source for
nearly exhaust-free automobiles and how they can be used as electricity-generating
plants. The high cost of manufacturing fuel cells has prevented
the mass use of this valuable energy source.
Ocean sources. Oceans, which cover more than
70% of the Earth, contain both thermal energy from the sun’s
heat and mechanical energy from the tides and waves. Ocean thermal energy conversion (OTEC) converts solar radiation
to electric power. OTEC power plants use the difference in temperature
between warm surface waters heated by the sun and colder waters
found at ocean depths to generate electricity. The power of tides can be harnessed to produce electricity. Tidal
energy works from the power of changing tides but it needs large
tidal differences. The tidal process utilizes the natural motion
of the tides to fill reservoirs, which are then slowly discharged
through electricity-producing turbines. Wave energy conversion extracts energy from surface waves, from
pressure fluctuations below the water surface, or from the full
wave. Wave energy uses the interaction of winds with the ocean surface.
This technology is still in the exploratory phases.
Energy Statistics: The Canadian Encyclopedia