Science Focus Topic 7 Notes: Sources of Thermal Energy | Print |
This Topic expands on what you thought about and learned in Topic 1 about USING Energy. Much of the energy use for cooking and heating was found to be natural gas and electricity. These sources of Energy can undergo transformations before they are used for cooking and heating. There may also be environmental concerns in using each source of energy.

Chemical Energy

Chemical Energy can be transformed into Thermal Energy when wood, or coal is burned.

(Environmental Impacts: pollution caused by the burning of these fossil fuels)

Electrical Energy

Electricity is produced in many ways. Hydro-electric dams use the force of gravity which pulls the water over the dam to turn turbines, which are attached to generators, which produce the electrical energy from the mechanical energy of the generators.

Electricity can also be produced at
thermo-electric (fuel-burning) generating stations that burn fossil fuels.

(Environmental Impacts: wildlife in the area of the dam lose valuable habitat, plants may perish when the river which was blocked overflows its banks to create the reservoir for the dam, commercial enterprises may be adversely affected, pollution by the burning of fossil fuels, heated waste water can affect organisms in lakes where this waste water is dumped.)

Mechanical Forces

Mechanical forces that push or pull objects often release thermal energy, as do Frictional forces.

Geothermal Energy

Volcanoes, hot springs and geysers are sources of geothermal energy - energy from the interior of the earth. The thermal energy from these events can produce hot water or steam, which can be then piped to a power plant at the surface. This can be used to run turbines which produce electrical energy. HRD (hot, dry rock) can be used as another technique to generate thermal energy. (Water is pumped into cracks in the earth's crust. It returns to the surface as steam, which can be used to generate electricity.

(Environmental Impacts: more extensive use of this clean and environmentally friendly technique, could reduce the threat of oil spills, the pollution caused by burning fossil fuels and the wastes from mining fossil fuels.)

Solar Energy (A Solar Energy Information Resource)

Solar energy is clean and is guaranteed not to run out. It is not available all the time (nighttime, less in winter/ than in summer).
There are two techniques that can help to overcome these issues. (See Figure 3.32, page 243)
Passive solar heating - uses the materials in the structure to absorb, store and release the solar energy.
Active solar heating -
uses mechanical devices to collect and distribute the thermal energy.

(Environmental Impacts: none)

Wind Energy

Wind energy is the energy of moving air, and is a result of solar energy and convection. As the sun heats up the air, the warm air rises and cools off. The cooler air falls, creating the convection currents called thermals. These convection currents on a global basis, form the Earth's wind systems. The windmill is a turbine (a wheel with fan blades), which is connected to a generator. When the windmill spins the generator produces electricity.

(Environmental Impacts: aesthetics)

More Sources of Thermal Energy

The living organisms burn food (chemical energy) in their bodies to generate body heat (thermal energy).

A composter is another source of thermal energy. Decomposers break down food and as these chemical changes occur, thermal energy is produced, which in turn helps speed up the process of decomposition.

(Environmental Impacts: waste management)

Fossil Fuels

An energy resource is anything that can provide energy in a useful form. Most energy supplies come from fossil fuels (in Alberta and throughout the world). Fossil Fuels are chemicals from plants and other organisms that died and decomposed millions of years ago and have been preserved underground.

(Environmental Impacts: global warming, changing climate zones around the world, plant growth, depleted water resources and thermal pollution)

Fossil Fuels: Two Problems

The widespread use of fossil fuels has created 2 primary problems.

1- these energy sources are non-renewable and their supplies are running out
2- they produce toxic chemicals which can harm the environment by producing a
greenhouse effect resulting in global warming

Co-generation uses some of the two-thirds of the energy release by the burning of fossil fuels as thermal energy, to heat a building, or a fuel, to generate electrical energy.

Topic Review p. 247