This type of solar heating takes advantage of the greenhouse
effect. Sunlight comes into a room through glass walls and ceiling.
This energy is converted into heat, which is then trapped in the
walls, or else used to heat water tanks which can then act as
thermal reservoirs. At night these reservoirs continue to heat the
This type of system uses solar panels mounted on a roof. These
solar panels have water running through them. The water is heated
and then goes into the home where it can be used to heat water or
In this type of a system thin wafers of purified silicon which
have trace amounts of gallium and cadmium are exposed to light. This
light causes electrons to be emitted which creates a electrical
current. Some hand held calculators take advantage of this system.
The problem with this energy source is currently it is more
expensive than traditional energy sources. The good news is the
price is dropping rapidly. In 1980 it cost about 90 cents/kwatt.
Currently the cost is down to 12 cents/kwatt.
This type of energy is limited to a few areas of the west in the
U.S. and is non-renewable.
Potential of less then 10%.
In this type of a system steam is used to run the turbines which
create electricity. The magma is probably around 2,000° F. This system
will probably only last 10's of years before the rocks have been
Although the aforementioned geothermal system has very limited use
there is another system that could take advantage of water in the
earth. About 10 feet below ground the earth is unaffected by seasonal
changes and keeps a constant temperature of about 52 deg F on Long
Island. A vertical closed loop system which had pipes filled with
water going down into the ground until heated to 52 deg F and then
brought back out into a home could be used as a heating system in the
winter, and a cooling system in the summer. The water temperature
would be perfect for air conditioning in the summer.Water being heated
in the winter would require considerably less energy to raise it from
the 52 deg F then would much colder air in the winter months.
In some confined estuaries and bays the difference in water height
between low and high tide can vary significantly.
In the Bay of Fundy a pilot project was set up to take advantage of
the huge difference in water heights.
A turbine system was set up to take advantage of the rapid rushes of
water both in an out of the bay.