A big problem with solar energy is cost. Solid state solar cells are relatively expensive. The bottom of the food chain from which all live on earth is dependent is photosynthesis. A plant leaf takes water, carbon dioxide and sunlight and produces sugar and oxygen as a byproduct. This is called the Calvin Cycle and is the basic process of photosynthesis.
The efficiency of a leaf at 77 degrees Fahrenheit is about 5 %. Current solar cell efficiency is about 6 %. If solar cells become inexpensive enough they can be used in large quantities like plant leaves. Another way to produce energy is to use parabolic mirrors to focus energy from the sun on a container of fluid to produce steam. Also parabolic mirrors have been used to focus energy on a Stirling Engine and a container of molten salt has also been used. The molten salt arrangement allows for the storage of energy for bad weather and night time. Electricity is generated from the steam produced as the molten salt cools. Various configurations of generating power using mirrors are being used throughout the world. Basically a “mirror farm” is set up in an area where there are no tall buildings or hills to block the sun. The more mirrors the more concentrated sunlight for generating power. The “mirror farm” has to be off limits due to the fact that the focal point of the mirror (which is an area close to and in front of the mirror) is an area of intense heat.
The correct term for this type of power generation is called CSP ( concentrated solar power). The CSP process drives steam turbines like coal or oil fueled power plants but without the green house emissions. This helps in the fight against global warming. The question is where does this type of power generation fit in the United States. Ideally CSP works efficiently in desert areas because of its dependency on sunlight. Also in deserts there are less overcast days.
A CSP plant is currently in operation in Spain near the town of Seville. The plant supplies about 3 % of Spain’s power needs. A company in California operates a smaller CSP plant and is successful. A balanced approach is needed in regards to power generation. Solar power generating plants whether using solid state solar cells or arrays of mirrors are susceptible to wind damage. Earth quakes and flooding are also more of threat to these types of power plants. In an emergency just when power is needed the most it may not be available. Other sources of power such as oil, gas and wind are still needed.
In the past the earth has experienced large discharges of debris from volcanic eruptions which could effect the operation of solar plants. A recent example is the eruption of MT. Saint Helens volcano in Washington state. The eruption column reached a height of 80,000 feet in less than 15 minutes. Detectable amounts of ash covered 22,000 square miles. As much as 1 inch of ash was measured on the ground 300 miles downwind. A varied approach to power generation is needed to spread the risks.