Download TOPIC 7 -SOURCES OF THERMAL ENERGY P. 238 Most of the

TOPIC 7 -SOURCES OF THERMAL ENERGY P. 238
Most of the energy for heating and cooking comes from natural gas or electricity. Often
these energy sources go through a series of conversions before they turn into thermal
energy.
Ex. Hydroelectric Dams – the water turns the turbines (mechanical energy) and then the
energy from the turbines is converted into electrical energy.
Sources of Energy:
Chemical – chemical energy is stored in materials such as firewood, coal and fossil fuels
and is released in the form of thermal energy
*People also contain chemical energy, which is released as thermal energy, do you know
how?
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Mechanical – mechanical forces that push or pull often release thermal energy. Ex. Car
brakes (friction)
Geothermal Energy – energy from the earth’s interior
(can be converted to electrical energy by turbines)
Electrical – kinetic energy is transformed into electrical energy in hydro-electric dams.
Burning fuels converts chemical energy to thermal energy which boils water and
produces steam to spin turbines and produce mechanical energy. The mechanical energy
turns a generator which produces electrical energy.
Solar Energy – energy from the sun
Two Types:
1. Passive – uses materials to absorb, store and release solar energy (Ex. Windows
on the sunny side of a house)
What other materials could you use in your house to collect or absorb heat during the
day and insulate your house at night?
2. Active – uses mechanical devices like fans to distribute stored thermal energy.
The sun heats the water or air which is then pumped throughout the building. What
color are the solar panels? Why?
Wind Energy – energy of moving air (can be used to produce electrical energy)
Wind energy is the result of solar energy because as the sun heats the air the warmer air
rises and the cool air falls causing a convection current. These currents form our wind
systems.
Living Organisms and Composting – living organisms produce thermal energy.
Composters are also an energy source because as the food is broken down by
decomposers (worms) the organic material releases thermal energy.
Fossil Fuels – (coal, oil and gas) chemicals from plants and other organisms that died and
were buried millions of years ago and today they are burned for fuel.
In Alberta 66% of our electrical energy comes from burning coal.
Problems with Fossil Fuels:
1. These energy sources are non-renewable and the supply is running out.
2. They produce carbon dioxide gases which can harm the environment
(Global Warming (excess CO2), acid rain, smog etc.)
In order to keep our environment healthy we are looking at using alternative energy
sources:
- hydroelectric dams
- geothermal
- passive and active solar
- wind energy
- cogeneration
- nuclear
- biomass
- tidal