Fossil Fuel Power Plants: how Electricity is Generated.

Fossil fuel power plants produce the electricity which is the lifeblood of the developed nation, and we all rely heavily on it in our daily lives. The majority of current power stations run on fossil fuels. While solar energy power stations are being developed around the world on commercial scales, it is true to say that over 70% of every developed nation?s energy comes from fossil fuel electricity generation. In Australia, over 90% of our electricity is sourced in this way.

Power stations supply the main energy grid with electricity on-demand; that is, the greater the demand the more the power stations churn out.

That means that the greater the demand for electricity, the larger the amount of coal, oil or gas the fossil fuel power station will be consuming. A clear explanation of how the power stations turn fossils into electricity is in order.

An iron bar is made of lots of tiny iron crystals. When all these crystals are aligned, the iron bar will produce a magnetic field. Compasses are tiny magnets that align with the earth?s magnetic field. Have a look at this simple experiment in which you can make your own compass. Early compasses were simply lumps of magnetic iron-rich rock called lodestone.

Why iron does this and many other metals cannot is due to the arrangement of electrons in the d-subshell of each atom. Discussion of that topic is beyond the scope of this website.

It turns out that the magnetic field of a bar magnet looks something like this:

Those lines around the magnet are the FORCE LINES; they make up the magnetic field. Those field lines are able to push free electrons around so that they align with the field lines.

If we make a coil of copper wire and push a magnet through it quickly the electrons will move in one direction and you will have a current. Copper is used because it conducts really well, but any metal can be used for the wire. The reverse is also true; if we push electricity through a copper coil, it will generate a magnetic field. That is called an electromagnet. Electromagnets usually have an iron core to improve the magnetic field.

Now if we take one electromagnet and spin it inside another coil, the field from the electromagnet will create a current flow in the second coil. This is because the magnetic field pushes the electrons in the second wire coil.

Just like any other electrical device, the turbine needs to be connected to a circuit to allow electrons to flow in a loop. The electricity grid that the turbine is connected to is one enormous loop.

Now we have a spinning turbine causing electrons to be pushed out into the loop with some force, the force given to them by the magnetic field. The faster they are going the more energy they have and so the more work they can do for us in our homes.

This is where the fossil fuels come into the equation. Energy is needed to turn the turbine, and that energy needs to be harvested from somewhere. Possibilities include wind, falling water, waves, or steam. Traditional power stations use steam.

The coal (or oil or gas) is burned in a furnace. The furnace heats water in a boiler. This generates super heated steam that turns turbines. The steam is then cooled in cooling towers and condensed back into water to be returned to the boiler, reducing heat loss as much as possible. Some steam has to be released in the cooling process; that?s the source of those big white clouds coming out of the power station cooling towers. Here?s a picture of the process:

The exhaust gases are also used to heat the boiler chamber before being released via the chimney stack. This is where the environmental nasties such as CO2, NO, SO2 and ash, called fly ash, are released into the air.

The amount of coal going into the boiler, and therefore the amount of Carbon Dioxide and other gases being emitted from this fossil fuel power, is determined by our actions. We can reduce the amount of pollution from the power stations by using less electricity.

While we are still operating the majority of our power stations as fossil fuel power plants this is crucial; lower energy demands mean less pollution.

Return from Fossil Fuel Power Plants to Fossil Future or return to the Green Planet home page for more Solar Power Facts.

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