Much of the energy
we now use is indirectly solar.
While humans now
harness energy at about 13 terawatts, the sun delivers
energy to the earth at a rate of approximately 80,000 terawatts. This is
evidence that the sun gives humans more potential energy than they could
ever use.
Solar energy can be
used in small-scale applications.
It can be used to
warm and light homes.
Passive solar
design of houses and buildings is an effective way of
capturing heat and light. Passive solar design involves the construction of
buildings with large south facing windows and skylights. The building should
also be well insulated in order to trap heat.
Flat-plate
collectors are black metal plates that absorb heat from the sun
and transfer it to a liquid. The heat of the hot liquid can then be used as
energy.
More advanced
active solar collection is done with mirrors, reflectors, and
lenses that superheat a liquid. This liquid is then used to generate
electricity
Solar energy
can be used to generate electricity with photovoltaic cells.
These cells use semiconductor technology.
Advantages:
Solar energy is 100% renewable.
Solar energy releases no emissions
or pollutants.
Sunlight is free.
Production of solar arrays uses only 3% of the fossil fuel that would be
burned in a coal-burning power plant.
Photovoltaic systems can operate in remote areas with either direct or
diffuse sunlight.
Disadvantages:
Passive solar design is not easily applied to larger, more compact
buildings.-Solar systems have to cover large areas of land due to the
diffuse nature of sunlight.
Energy form the sun is intermittent (the sun only shines during the day).
Using photovoltaic cells to generating electricity is about 6 times as
expensive as using fossil fuels.
