Forms of Energy
The Ultimate Energy Source
We have seen that there are many forms of energy including chemical, potential and kinetic and that the total energy of the universe is unchanging.
But, in some way, the energy here on Earth does change because the Earth receives a large amount of energy from the Sun. Without this steady supply of energy, the Earth would eventually dissipate its own energy into heat that spreads out into the universe and cool down to a very chilly -456°F.
Heat and light from the Sun not only warms the Earth to a comfortable temperature, but is also ultimately responsible for most all of the "other" forms of energy we commonly think of.
Sunlight drives photosynthesis in plants producing the chemical energy we consume when we eat. Sunlight drives the weather patterns of wind and rainfall whose potential energy can be recaptured by wind turbines and hydroelectric facilities, respectively, Ancient sunlight grew the prehistoric forests that have now become the many forms of fossil fuels (coal, oil and gas) that are used today.
Although the Sun is the ultimate source of most of our Earthly energy, energy here on earth is broadly divided into either renewable or non-renewable forms.
Renewable Energy Sources
Solar, wind, biomass, hydroelectric, and geothermal energies are classified as renewable because, as long as our sun continues to shine (which is projected to continue for another 5 billion years), its steady outflow of energy will continue to appear on our planet in these forms. Although classified as renewable, geothermal energy is not a direct consequence of solar radiation, but rather the result of nuclear decay processes that generate heat at the earth's core.
Non-Renewable Energy Sources
Coal, oil, natural gas, and nuclear energies are classified as non-renewable. Unlike the above renewable energies, these energy sources are not currently generated by the sun, but are ancient products of our planet's long history. Coal, oil, and natural gas are the result of biomass, grown millions of years ago, that has since fossilized over time into burnable fuels. Because the process of fossilization requires such enormous time periods, these fuels cannot be replenished in any practical way.
Pros and Cons
Currently, much of the energy used in the US is derived from non-renewable sources, primarily coal, oil and natural gas.
Non-renewable energy sources are convenient. Coal, oil, natural gas and nuclear can all be gathered from the Earth and stockpiled to be used whenever needed. They are "on demand" energy sources, already packaged for immediate use.
The primary drawback to these fuels (with the exception of nuclear) is that their energy can only be released through a chemical reaction with oxygen commonly known as burning. In this process, gases, most notably carbon dioxide, are released as byproducts. Carbon dioxide is not itself toxic - we all exhale this gas from our lungs when we breath - but, according to the US Environmental Protection Agency, there is growing conviction among the science community that increasing levels of this, and other such, gases in our atmosphere is having a detectable effect on the world's climate.
Renewable energy sources (with the exception of biomass) do not involve burning, but rather a direct transformation of energy from one form to another (chiefly into electricity). These sources are "clean" in the sense that they do not generate detrimental gas byproducts.
The drawback to these renewable energy sources is their relative inconvenience in comparison with fossil fuels. Although these energy sources arise from a steady influx of energy from the sun, the actual amounts of sunlight, rainfall and wind vary locally on our planet and limits our ability to rely on these energy sources for "on demand" usage. Unlike the fossil fuels, this energy is not conveniently packaged for immediate use. Instead, novel strategies for storing this clean energy are needed to collect and package this energy so that it can be used whenever needed.
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