In Perspective - Solar Power
It maybe a little difficult to talk about solar power as we reach the shortest day of the year, but the thought may warm your heart a bit even though the temperatures are below freezing. Solar power comes in two varieties, active and passive. We are familiar with the passive, where the sun warms us with radiant heat. Active is becoming more common in our technology age with solar panels. Solar panels are a true American invention, but in this energy efficiency world it is Germany and Japan that lead the world in solar panel production.
Solar panels aren’t as efficient as other sources of energy, yet. Where coal and nuclear plants are around 30% efficient, solar panels are around 20% efficient. But there are some really promising breakthroughs that have solar people excited and could raise efficiency ratings closer to 45%. Of course the application of solar is changing. There are roof shingles and windows that produce electricity and the possibility of house paint and siding producing power.
Passive solar is actually ancient technology that has been ignored over the past century. Houses used to face the south to take advantage of winter solar energy while using roof overhangs to limit the summer solar heat. It was also more effective to place more windows on the south face of the building to take advantage of the light and radiant energy for the interior of the house.
Another passive solar technology that has been ignored is solar hot water heating. Thirty percent of residential energy use is heating water and while solar hot water heating doesn’t work 24 hours a day most homes already have hot water storage. China is the leader in solar hot water unit production. Israel has the most units per capita and it is estimated that the country saves two million barrels of oil a year using the technology. It isn’t just for warm weather countries. The Scandinavian countries have been using solar water heating to supplement their heating systems producing around 20-25% of their hot water needs.
On a bigger scale, power companies are using both active and passive to generate electricity. Europe is considering building a large solar panel farm in northern Africa along with a power line to feed electricity into Europe. Spain already has a large mirror type plant that focuses solar energy to a point that they call concentrating solar power. It is based on a legend that Archimedes used polished shields to concentrate sunlight on the invading Roman fleet. Portugal and Germany both have similar plants.
The U.S. has a few parabolic solar plants in the southwest that have been producing electricity since as early as 1984. The U.S. can also claim the largest solar plant in the world covering more than 1,600 acres. This technology uses a parabolic mirror to focus the sunlight on a tube of synthetic oil that is heated to around 700 degrees which is then used to heat water and drive turbines. A similar technology is used in some of the residential hot water heaters increasing their efficiency to produce 75% of the hot water needs for a typical New York home.
Solar power is worth looking into if you are looking for a long term investment. Combining both passive and active solar energy is being used to create what is called the net-zero home, all energy needs produced on the site. This isn’t a futuristic idea, homes across the country are starting to pop up that have no heating, hot water or electric bills.
http://en.wikipedia.org/wiki/Solar_Energy_Generating_Systems