Solar Power is Free energy from the Sun!
Posted by Laird on May 14, 2008
Introduction
How it works.
We’ve used the Sun for drying clothes and food for thousands of
years, but only recently have we been able to use it for generating power.
The Sun is 150 million kilometers away, and amazingly powerful.
Just the tiny fraction of the Sun’s energy that hits the Earth
(around a hundredth of a millionth of a percent) is enough to meet
all our power needs many times over.
In fact, every minute, enough energy arrives at the Earth to meet
our demands for a whole year - if only we could harness it properly.
How it works
There are three main ways that we use the Sun’s energy:-
1
Solar Cells (really called “photovoltaic” or “photoelectric” cells)
that convert light directly into electricity.
In a sunny climate, you can get enough power to run a 100W light
bulb from just one square meter of solar panel.
This was originally developed in order to provide electricity for satellites,
but these days many of us own calculators powered solar cells.
2
Solar water heating, where heat from the Sun is used to heat water
in glass panels on your roof.
This means you don’t need to use so much gas or electricity to heat
your water at home.
Water is pumped through pipes in the panel.
The pipes are painted black, so they get hot when the Sun shines on
them.
This helps out your central heating system, and cuts your fuel
bills. However, in the areas of the world that chill in winter months, you must remember to drain the water out
to stop the panels freezing.
Solar heating is worthwhile in places like California and Australia,
where you get lots of sunshine.
Mind you, as technology improves the use of the ‘drain-back’ system which
avoids problems with freezing in cold conditions, will allow that more northern countries
to at least use these solar systems for 9 months of the year.
3
Solar Furnaces use a huge array of mirrors to concentrate the Sun’s
energy into a small space and produce very high temperatures.
There’s one at Odellio, in France, used for scientific experiments.
It can achieve temperatures up to 33,000 degrees Celsius.
Solar cells provide the energy to run satellites that orbit the
Earth. These give us satellite TV, telephones, navigation, weather
forecasting, the internet and all manner of other facilities
In California, the Solar One power station uses the Sun’s heat to
make steam, and drive a generator to make electricity. The station
looks a little like the Odellio solar furnace , except that the
mirrors are arranged in -circles around the “power tower”.
As the Sun moves across the sky, the mirrors turn to keep the rays
focused on the tower, where oil is heated to 3,000 degress Celsius, The
heat from the oil is used to generate steam, which then drives a turbine,
which in turn drives a generator capable of providing 10kW of electrical
power.
Solar One was very expensive to build, but as fossil fuels run out and
become more expensive, solar power stations may become a better option.
Energex (Australian power company): Animation of how a solar cell works at
www.energex.com.au/switched_on/activities/photovolatic/photovoltaic.html
One idea that is being considered is to build solar towers.
The idea is very simple - you build a big greenhouse, which is
warmed by the Sun. In the middle of the greenhouse you put a very
tall tower. The hot air from the greenhouse will rise up this tower,
fast - and can drive turbines along the way. This could generate
significant amounts of power, especially in countries where there is
a lot of sunshine and a lot of room, such as Australia.
See a video of this at
http://www.enviromission.com.au/project/video/video.htm
See also: www.fuelfromthesun.com
Advantages
Solar energy is free - it needs no fuel and produces no waste or pollution.
In sunny countries, solar power can be used where there is no easy way
to get electricity to a remote place.
Handy for low-power uses such as solar powered garden lights and battery & chargers.
Disadvantages
Doesn’t work at night. Very expensive to build solar power stations.
Solar cells cost a great deal compared to the amount of electricity
they’ll produce in their lifetime.Can be unreliable unless you’re in a very sunny climate.
In the United Kingdom, solar power isn’t much use except for low-power applications,
as you need a very large area of solar panels to get a decent amount of power.
Is it renewable?
Solar power is renewable. The Sun will keep on shining anyway, so it makes
sense to use it.
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