PV Gap

Leslie Said:

What are some postives and negatives about solar power plants?

We Answered:

Good things:

- the sun will continue to provide power for at least another several billion years
- solar power generation does not produce any waste like CO2 or radioactive materials

Bad things:

- solar power is only available during the day.
- solar cells are only 10% efficient. This makes solar power stations very large.

Inevitable things:

- fossil fuel and nucleur materials are non-renewable.
- a large amount of CO2 is generated by coal fired power plants. Global warming will cause the sea level to rise due to melting ice sheets at the poles. By 2050, it is estimated the sea will rise 3 feet. If all the ice melted, most coastal cities would no longer exist. Large areas of land at sea level would also vanish. In the USA, Florida would dissapear, along with cities like New York, Los Angeles and Nerw Orleans. Countries like Vietnam and Bangladeesh would loose most of their land to the sea.

Sue Said:

How Many Solar Power Plants Are There In The Us/World?

We Answered:

If you mean utility-owned central plants, I think the number is very low, less than 100, and maybe less than 20.

If you count small private producers, like solar farms in Germany, I'd estimate the number is in the tens of thousands.

If you count solar rooftops, which contribute energy to the grid the same as the power company, the answer would be in the millions, with 100,000 of that in the USA.

Nathaniel Said:

what are some postives and negatives about solar power plants?

We Answered:

While some commercial electrical power plants use photovoltaic panels most are using solar thermal collectors (aka concentrators) in one of these configurations:

solar power tower
solar parabolic trough collectors
solar parabolic dish collectors
solar chimney
solar pond

each configuration has specific positives and concerns. For general considerations, I see the concerns as simply indications of where work is needed if the overall positive aspects are a goal worth achieving. Conversely the same negatives with any other type of power source can be positives for solar installations.

General positives would include:
-no fuel costs
-no air, water, or land pollution in the operation of the facility
-no short or very long term hazardous waste or by product storage problems
-will not promote industries that wreck the land in production for its fuel
-will not promote the transportation of fuel that may be hazardous if it spills
-at the end of its life the plant will not itself be radioactive or hazardous waste
-uses a clean fuel that makes all the ultimate users of its electricity (like electric cars) cleaner as well
-many of the installations are divisible, modular and scalable. (only part of the plant can be shut down for maintenance if necessary reducing spinning reserve considerations)
-some installations have few moving parts to break or wear out
-public perception that the utility cares for the environment (political positives)
-diversification with existing power installations in case of future political or environmental problems.

XX - -Required land area is often mentioned as a drawback to solar plants but this fails to acknowledge the land area required to produce, refine and transport fuel for conventional facilities. Overall, I estimate that solar facilities require less land, and land that has more marginal use, than conventional facilities.

Issues with current solar power technology:
-need to locate facilities in high sun, often desert areas: this may have an impact on desert environments: but this may be preferred to an impact national forests, wildlife preserves or food producing or urban areas. Facilities in space may be an ultimate answer and not an issue.
-distance from usage: will only require more work on electrical power transmission. This will encourage already needed efficiency improvements with HVDC transmission and other possibilities.
-lack of storage for night time / cloudy periods: The entire grid lacks needed storage making it very inefficient. The potential for solar power just makes the payback for electrical storage even greater. Some solar thermal facilities can store energy as heat helping energy storage generally.
-use of water supplies for cooling: Thermal power plants Solar or conventional need cooling. Solar facilities in desert areas will need to recycle water or use potential geo thermal cooling. Photovoltaics don't share this issue.
Expense vs output: This is a very tricky issue. It is not enough to consider expense alone. Current solar plants are expensive. This makes their output seem more costly than conventional sources. But subsidies and pollution are often not figured into this equation. While costs will not go down with conventional plants, as an emerging technology they will drop with solar installations. We plan for such facilities to last more than 30 years. Costs can go down severely as the production is increased. Some like parabolic dish (most collector to grid efficiency) and photovoltaic cells can be factory produced and assembled on location with a tremendous potential savings over the existing custom built plant structure.

We pay for pollution with our lives and our medical costs but not through our utility bills. We pay for every nuclear power plant with the concern that someone will use the technology as an excuse to create a weapon. As we die a little each day it is easy to say that solar is "more expensive." But we should be careful that we don't claim that the fruit that we don't reach for was "sour anyway."

Denise Said:

Do solar power plants require considerable space and plenty of sunshine to function correctly?

We Answered:

Esentially, yes.
You need space, because the current is proportional to the area covered(which is proportional to the energy it receives => more area = more current).
And the more sunshine, the more energy you can gather.
Since production of solar panels is still expensive, you want to place them somewhere with a lot of sunshine.