Nuclear reactors

Download 12.82 Kb.
Date conversion15.05.2016
Size12.82 Kb.

There are only two sources of energy on our planet: solar, and nuclear
Nuclear power comes in two forms:
Nuclear reactors: Uranium (and in some cases Plutonium) atoms are split and the heat produced is

converted into electricity (supplies 6 % of world energy)

Geothermal energy: nuclear decay of atoms keeps the earth’s interior warm, in a few places hot magma

bodies are close enough to the surface to generate steam for electrical generation

(supplies 0.2 % of world energy)
Although most people think of solar energy as the direct conversion of sunlight into heat and electricity, most solar energy is indirect:
Wind: as the sun heats some areas of the earth more than others, pressure changes in the atmosphere cause

air masses to move from high pressure to low pressure (supplies 0.3 % of world energy)

Hydroelectric: sunlight evaporates water from the ocean and lifts it up above the dam

(supplies 3 % of world energy)

Biofuels: corn, soybeans, sugar cane and other crops convert sunlight into chemical P.E. in sugars and

starches, which are then converted to ethanol and biodiesel (supplies 0.2 % of world energy)

Coal: ancient trees converted sunlight into chemical P.E, which was converted to coal by the heat and

pressure in the earth’s crust (supplies 25 % of world energy)

Oil, and natural gas: ancient oceanic plankton converted sunlight into chemical P.E, which was converted

to petroleum compounds by the heat and pressure in the earth’s crust

(supplies 60 % of world energy)

The graph below shows US energy consumption since 1850. Notice how almost all the energy we use is oil, coal, and natural gas (fossil fuels)

There are two big problems with our continued reliance on fossil fuels:

  1. they are running out

  2. using them has a negative impact on both the climate and the chemistry of the oceans

How long will our fossil fuel reserves last? Estimates vary. Many research groups and governmental agencies estimate that at current rates of consumption

Coal will run out in 150 years

Oil and natural gas will run out in 30 – 100 years

Environmental impacts of fossil fuel usage:

There is growing concern among almost all scientists that the continued usage of fossil fuels is causing a catastrophic change in the chemistry of the atmosphere and world ocean.

The problem is that in order to extract the energy from fossil fuels you have to release CO2 into the atmosphere, disrupting the normal Carbon Cycle.
Carbon Cycle:

1. Plants take CO2 out of the atmosphere to form high energy carbon compounds like sugar and starch

2. When the plants are eaten or burned, the carbon compounds release energy and turn back into CO2

3. Prior to the 1800’s the amount of CO2 released by eating or burning plant materials was equal to the

amount that plants took out of the atmosphere, so the level of CO2 in the atmosphere remained steady at

about 260 ppm (parts per million)

All fossil fuels (coal, oil, natural gas) were formed when ancient plant matter was buried before bacteria could “eat” it and release its energy and CO2.
All fossil fuels (coal, oil, natural gas) contain Carbon atoms that combine with Oxygen to form CO2
As a result, when fossil fuels are burned, they release CO2 that has not been part of the atmosphere for millions of years. Since humans started using fossil fuels, the concentration of CO2 has gone from

260 ppm to 387 ppm.

Why does increased CO2 make the world hotter?

The Earth absorbs visible light from the sun and converts it into thermal energy, making the surface warmer. The thermal energy in the Earth’s surface is converted into infrared light and radiated into space, making the surface cooler. As long as these two processes remain constant, so does the temperature of the Earth’s surface.

CO2 traps infrared light, so the more CO2 there is in the atmosphere, the less infrared light escapes into space. As less infrared light escapes into space, the thermal energy of the planet goes up.
What happens as the Earth gets hotter? The atmosphere is very complex, so one knows for sure, but computer models (and recent data) suggest the following consequences of increased atmospheric temperatures:

  • Ice caps and glaciers melt

  • Sea level rises

  • Weather patterns change and become less predictable

  • Large storms become more frequent and violent

  • Drought and forest fires become more frequent and severe

  • Many species become extinct as habitat changes

What’s this about ocean chemistry?

Just like it does in a bottle of soda, atmospheric CO2 dissolves into sea water. When CO2 dissolves into water it forms Carbonic Acid, which lowers the pH, making the water acidic.

As the ocean water becomes more acidic, it makes it more difficult for many organisms to survive.

Consider this: 80% of the oxygen in the air comes from plankton in the oceans – what if they die off?

Your generation is left with a choice: fix the problem, or wait and see where our current path takes us.

Any answer to the problem must involve drastic reductions in the use of fossil fuels

The two most important things to do are:

  1. Reduce current energy use through conservation and improvement in efficiency

  2. Develop a variety of energy sources that do not involve fossil fuel (see list on front)

Like it or not, the fate of the world is in the hands of your generation – please, make wise choices.

The database is protected by copyright © 2016
send message

    Main page