09.14 - Solar and geothermal Solar Power Solar heat used...

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1 Solar and geothermal Geothermal pump Photovoltaic panels Solar Power •Solar heat used directly to heat swimming pools, etc. •Small-scale solar cells used to power small used to power small devices, e.g. calculators •Photovoltaic panels used to produce electricity in distributed locations (rooftops) and large power plants Photovoltaics •A photovoltaic solar cell is a semiconductor device, typically made of silicon. •A unit of light energy (a photon) is absorbed in the cell and the energy is given to an electron energy is given to an electron, which results in an electrical current. •The typical efficiency is only about 6-10%. Despite determined efforts, this value has not improved significantly in ~20 years. Solar Power Statistics •Total worldwide installed photovoltaic power is about 2000 megawatts, compared with 60,000 megawatts of wind power. •A very large PV power plant is 10-50 megawatts. However, plans are in place to build 300+ megawatt plants around the world.
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2 Solar Power Statistics Current cost per kW-hr is 5-10 times higher than fossil fuels. Mostly because of enormous capital costs. 12 MW photovoltaic plant in Germany Solar Pros and Cons Pros: •Amount of solar energy reaching the earth is 10,000 times the amount used by humans. •Renewable •Minimal greenhouse gas emissions or other pollution •Can work in isolated locations •Low ongoing operating costs, little maintenance Solar Pros and Cons Cons •Very expensive capital investment •Lower power density, requires large areas and many solar cells •Cannot be used to power vehicles directly •Intermittent Limitations of Wind and Solar Power Wind and Solar energy both suffer from several fundamental limitations Intermittency - cannot match supply to demand • Location - supply sites may be far from demand sites • Not portable - generation of electricity only accounts for a fraction of energy use. The transportation sector needs fuel.
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This note was uploaded on 02/26/2008 for the course CHEN 1000 taught by Professor Degrazia,j during the Fall '04 term at Colorado.

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09.14 - Solar and geothermal Solar Power Solar heat used...

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