PV Gap

Bessie Said:

1. How does solar energy compare with fossil-fuel energy...?

We Answered:

The energy in fossil fuel is primarily from solar energy. Using fossil fuel is a way of utilizing stored solar energy that was stored by plants such as phytoplankton, or in the case of coal, larger trees and plants, as well as small microscopic animals called zooplankton. As their bodies accumulated in sediment where there was little or no oxygen, they built up large quantities of stored solar energy in the form of chemical energy contained in the hydrocarbons that their bodies were made from. Eventually the organic material was heated by the earth which gets most of its energy from decay of radioactive elements (also known as nuclear fission) and by the pressure created by gravity, forming oil, natural gas, or coal. Thus all fossil fuel really is a concentrated form of solar energy from the sun with some amount of energy sourced from nuclear energy of the earth.

The biggest difference between solar energy and fossil fuel energy is that solar energy has not been stored in the form of chemical energy as it has in fossil fuels. The result is that solar energy is far less concentrated than fossil fuel energy.

So the three biggest fundamental problems with solar energy are due to this difference:

1. solar is not highly concentrated energy, so to utilize solar energy large areas must be covered with collection panels
2. solar energy on the surface of the earth is interrupted by rotation of the earth, and during the night is often when we need energy the most, plus we have no electrical grids that span across continents
3. conversion of solar energy to electricity or some other form of energy is very inefficient. Solar panels are not highly efficient at converting sunlight to electricity. Electric transmission is very inefficient. Storage of electricity is very inefficient using batteries and other methods of storing energy are needed if we expect to rely on solar energy.

The biggest problem is actually the first one in my opinion. For example, the largest solar power generation plant in the world is currently being built in Blythe, California. It will cover 11 square miles of California desert (a unique and valuable habitat for several endangered species) and generate 1 million peak kilowatts. Compare that the electricity generated only from natural gas in the United States, which is 1.5 Trillion kilowatt hours of electricity. To replace the power generated by natural gas alone (not counting the coal that provides the majority of electricity in the US) it would take 16 Million acres of land be covered with solar installations with present technology. The largest county in the contiguous United States is San Bernardino County, which is where this new large plant is being built. San Bernardino County is only about 13 million acres. It would take an area 20 times the size of the entire state of Rhode Island to be covered with solar power plants in order to replace the electricity generated by natural gas. And it would work only during the day.

The other problem with solar energy that makes it difficult to use for anything but a supplemental source of energy is that it is subject to weather and clouds. Natural gas power plants are used because they can be turned on and off easily to supply power whenever there is a spike in power demand and this capability makes it essential for preventing brown-outs and black-outs.

While one answer here says Germany has made solar a viable alternative to fossil fuel, the truth is that Germany still gets less than 1% of its electricity from solar power. That's hardly a "viable" alternative. German households already pay more than twice as much for electricity as US households, while German industry pays about 250% what its US counterparts pay.

http://en.wikipedia.org/wiki/Renewable_e…
http://theenergycollective.com/geoffrey-…
More reading:
http://www.thenewamerican.com/index.php/…

http://www.cnbc.com/id/39909532

http://green.blogs.nytimes.com/2010/09/1…

Nathaniel Said:

what are the three fundemental problem in harnessing solar energy?

We Answered:

http://www.geocities.com/dieret/re/Solar/solar.html

try to view this page... i hope it will help you

Manuel Said:

What makes it so difficult for tropical countries to harness solar energy?

We Answered:

Even though it may be compulsive option in the near futrue - its the cost factor which keeps us away. In many countries it is being used for street lighting / water heating etc.

Roger Said:

Is there other device in harnessing solar energy to electricity aside from solar cells?

We Answered:

Concentrating solar power (CSP) plants produce electric power by converting the sun's energy into high-temperature heat using various mirror configurations. The heat is then channeled through a conventional generator. The plants consist of two parts: one that collects solar energy and converts it to heat, and another that converts heat energy to electricity. Concentrating solar power technologies currently offer the lowest-cost solar electricity for large-scale power generation. However, due their big size, CSPs are not suitable for residential use. For more information, you can visit: http://solarcentral.org/drupal/?q=node/3…