|
|
04/10/02 - Note
Energy And Society
1
million years ago primitive people derived energy only from the food they ate,
around 8MJ/d per person. When fire was used by people for food and heat NRG
consumption increased to approximately 22MJ / d. By 5000 BC, when farming began,
personal NRG consumption was about 50 MJ/d. In the 15th century total
NRG consumption per person was around 110 MJ/d and in 1983 the value was 1200 MJ/d.
This trend is alarming.
Sources
Of Energy
NRG
sources are either classified as either renewable or non-renewable.
A non-renewable NRG source is one that is considered depleted once consumed.
Renewable sources are those that are replenished or replaced within a human
lifetime.
Oil
- Crude petroleum is a dark-greenish foul smelling mixture of hydrocarbons
and sulfur. It is formed by the compression of the organic remains of plants and
animals that died millions of years ago and were trapped under layers of
sediment.
Natural
Gas - Like petroleum, most of our natural gas was formed billions of years
ago by the decay of organic matter and is trapped in underground deposits. Natural
gas is one of the cleanest burning of all fossil fuels.
Coal
- Coal was formed millions of years ago much in the same way that petroleum and
natural gas were formed. Unfortunately, as well as being the most abundant
fossil fuel in the world, coal is also the most polluting to burn and the most
environmentally disruptive.
G.P.E.
– Hydro-electric power plants are the most common sources using GPE. Water is
collected at great distances from the ground and allowed to flow down pipes
spinning turbines. As water falls GPE is converted into kinetic energy used to
sin the turbines.
Nuclear
– Nuclear energy involves the process of fission. Fission of uranium fuel
generates heat that turns water into steam. The steam is then used to spin
turbines to generate electricity. Nuclear waste and accidents are of great
concern.