Solar energy refers to the utilization of the radiant energy from the Sun. Solar power is used interchangeably with solar energy, but refers more specifically to the conversion of sunlight into electricity, either by photovoltaics and concentrating solar thermal devices, or by one of several experimental technologies such as thermoelectric converters, solar chimneys or solar ponds. Solar energy has become increasingly attractive in recent years as a possible solution to greenhouse gas emissions and global warming. This is because it emits not greenhouse gases in the process of generating electricity. It is effectively a 0-emission source of energy. There are, however, critics of solar energy. As with the entire debate regarding solving global warming, the questions raised relate largely to the viability of solar energy as compared to other alternative forms of energy. The running question is whether governments and citizens should prioritize solar energy in plans to fight global warming over sources of energy. This debate, therefore, relates largely to comparing the pros and cons of solar energy to the pros and cons of other alternative forms of energy. The debate regarding solar energy is framed by numerous questions: Is solar energy valuable in reducing greenhouse gas emissions? Is it truly a 0-emission source of electricity? Is the manufacture of solar cells carbon neutral or does it involve the use of many fossil fuels? What back-up sources of energy does solar energy use for when the sun isn’t shinning? Coal? Are solar cells efficient? Are there any environmental risks associated with the use of cadmium in solar cells? Does solar technology require too much land? Is this an environmental, agricultural, and/or economic/costs problem? Is the disposal of solar energy batteries a environmental concern? What are the economics of solar power? Is it viable in the market place? Is the technology advancing quickly enough or slowly compared to other energy alternatives? Is solar energy supply consistent enough (no production at night)? Is location and climate (sunny weather) a major constraint? Can the electric grid handle the introduction of massive amounts of solar-generated electricity? Can solar energy generally supply massive quantities of electricity and replace significant quantities of coal production as well as other dirty forms of electricity production? See Wikipedia’s article on solar energy for more background.
Global warming is driven by the release of carbon dioxide and other greenhouse gases into the atmosphere. Solar energy emits none of these gases, and is abundant, so can dramatically slash greenhouse gas emissions and help reverse global warming.
The solar industry is competitive, bullish, and growing exponentially. BCC research believed it will grow from $13 billion currently to $32 billion in 2012. This means that solar energy is currently viable, and is replacing dirty forms of energy at an exponential pace now. This compares favorably to much more distant and uncertain forms of renewable energy. Why invest in these other renewables, when solar energy is ready to cut emissions exponentially starting now?
The fundamental quantity here is the energy payback time, i.e. the time, after which the system will have produced enough energy to cover its own construction. For crystalline Silicon solar cells in central Europe energy payback time is around 4 years. With the usual guaranteed lifetime of 25 years, this leaves plenty of time for the c-Si cells to actually produce electricity.
While the production of solar cells does use energy, there is no need for this energy to come from fossil fuel sources. It can, in fact, come from solar power. Solar power can, therefore, produce solar panels, and be 100% 0-emission from production to electricity generation. It should also be noted that “back-up” sources of energy needed not be fossil-fuel based.
Coal is the primary fuel for generating electricity around the world. Solar power cannot realistically produce enough energy anytime soon to replace this massive source of electricity. It is incapable, therefore, of making a serious dent in coal-electricity production and the related greenhouse gas emissions.
The most commonly used material in photovoltaic solar energy systems is crystalline silicon. Using this material for solar applications requires that it be highly refined. This process uses a significant amount of energy, often derived from fossil fuels, which can offsets emissions reductions associated with solar energy.
Because solar energy cannot supply energy at night and is dependent on good weather, it requires back-up sources of energy to fill the gaps. These back-up sources are often coal-based, since coal is the predominant fuel driving electricity production. This means that solar power’s inconsistency has negative consequences for the environment.
It does not pollute our air by releasing carbon dioxide, nitrogen oxide, sulphur dioxide or mercury into the atmosphere like many traditional forms of electrical generation.
Almost all modern sources of energy use the sun’s energy, but in a very indirect way. Oil is the byproduct of organic matter that grows via the power of the sun. Wind energy is the product of the sun causing thermal variables in the earth’s atmosphere. Yet, why not just exploit the sun’s energy directly with photovoltaic cells? This is more efficient.
Unlike carbon-based fuels and other non-renewable energy resources, solar energy will never run out for humans. This fact has very important implications. Solar energy can supply humans with an abundant amount of 0-emission energy thousands and even millions of years into the future.
Solar panals can be put in the middle of the desert, to avoid clearing rainforests and arable land.
Solar panels themselves contain cadmium, a silvery metal that is toxic in the environment. While solar panels are durable, eventually they will wear out and need to be disposed of. The toxins in these metals can subsequently be released into the environment.
Because the sun’s rays are diffuse, solar panels must occupy substantial territory to generate any significant quantities of power. As a result, solar energy is land-intensive, and creates a pressure to clear land of trees and vegetation to make way for solar panels. Owners of solar panels on home rooftops may also have an incentive to cut-down trees that are blocking solar panels from the sun’s rays. This is a significant ecological threat.