According to the International Energy Agency, solar energy provides about 0.5 percent of the current world energy supply. This could rise to a quarter by the year 2050, attenuating our dependency upon fossil fuels. Solar energy is not without its negative impacts, but on balance the rise of photovoltaic technology is beneficial to the entire Earth and the people who have to breathe its air.
Photovoltaic technology converts the energy of the sun into electricity. When the photons from sunlight strike the panel, electrons within the solar cells become excited and begin to move across the panel in such a way that creates a current. For this reason solar power is renewable. It can be used over and over again without any great effort, such as burning, needed to unlock its energy, so the environmental impact of solar during operation is minimal.
The one major impact of solar technology is it expansive use of land. One square kilometer of solar panels generates between 20 and 60 megawatts of power. However, this is not a problem endemic to solar power. Coal power requires just as much land per unit of energy, if the land used in strip mining is taken into account. Furthermore, most current solar panel farms exist out in the desert, where land is seldom needed for any other purpose. Solar energy also has no need of water for cooling.
Solar panels are made from heavy metals and other hazardous materials such as arsenic, many of which could be dangerous to the environment if improperly disposed of, but the same can also be said of coal and oil, which release heavy metals during combustion. Cadmium telluride, one promising component of photovoltaic technology, is a harmful heavy metal, but according to Vasilis Fthenakis, an environmental engineer at Brookhaven National Laboratory, the direct emissions from the production of cadmium telluride cells are 300 times lower than emissions from coal power plants, which carry out mercury and other heavy metals from smokestacks.
The U.S. Department of Energy states that fossil fuels, which generate electricity through burning, produce about two-thirds of sulfur dioxide emissions and a quarter of nitrous oxide emissions in the United States, causing smog and acid rain. In 2007, over 8 billion metric tons of carbon dioxide were released into the atmosphere, which is believed to contribute to man-made global warming and climate change. By contrast, solar panels produce no emissions during their operation. Solar energy is converted to electricity without any material byproduct.
Solar power has some unseen dangers during the manufacturing process that are still being debated. One compound called nitrogen trifluoride is used to etch surfaces on solar cells. About 96 percent of the gas breaks down and provides fluorine at the surface for etching, and only 2 percent ever escapes into the atmosphere. Nitrogen trifluoride is 17,000 times more potent as a global warming agent compared with carbon dioxide, but this is actually a marked improvement on alternative gases such as perfluorocarbons and sulfur hexafluoride, the latter of which was previously used but recently became regulated by the Kyoto Protocol. According to one NASA press release, "current nitrogen trifluoride emissions contribute only about 0.15 percent of the total global warming effect caused by current human-produced carbon dioxide emissions." Concentrations have risen from 0.02 parts per trillion in 1978 to 0.454 parts per trillion in 2008, far short of the 380 parts per million of carbon dioxide, though rising by 11 percent each year. In 2008 about 5,400 metric tons of the gas existed in the atmosphere.