Renewable
Resources:
Renewable resources are resources that are replenished by
the environment over relatively short periods of time. This type of resource is
much more desirable to use because often a resource renews so fast that it will
have regenerated by the time you've used it up.
Think of this like the ice cube maker
in your refrigerator. As you take some ice out, more ice gets made. If you take
a lot of ice out, it takes a little more time to refill the bin but not a very
long time at all. Even if you completely emptied the entire ice cube bin, it
would probably only take a few hours to 'renew' and refill that ice bin for
you. Renewable resources in the natural environment work the same way.
Solar energy is one such resource
because the sun shines all the time. Imagine trying to harness all of the sun's
energy before it ran out! Wind energy is another renewable resource. You can't
stop the wind from blowing any more than you can stop the sun from shining,
which makes it easy to 'renew.'
Any plants that are grown for use in
food and manufactured products are also renewable resources. Trees used for
timber, cotton used for clothes, and food crops, such as corn and wheat, can
all be replanted and regrown after the harvest is collected.
Animals are also considered a renewable
resource because, like plants, you can breed them to make more. Livestock, like
cows, pigs and chickens, all fall into this category. Fish are also considered
renewable, but this one is a bit trickier because even though some fish are
actually farmed for production, much of what we eat comes from wild stocks in
lakes and oceans. These wild populations are in a delicate balance, and if that
balance is upset by over fishing, that population may die out.
Water is also sometimes considered a
renewable resource. You can't really 'use up' water, but you also can't make
more of it. There is a limited supply of water on Earth, and it cycles through
the planet in various forms - as a liquid (our oceans), a solid (our polar ice
caps and glaciers) and a gas (as clouds and water vapor).
Liquid water can be used to generate
hydroelectric power, which we get from water flowing through dams. This is
considered a renewable resource because we don't actually take the water out of
the system to get electricity. Like sunshine and wind, we simply sit back and
let the resource do all the work!
Geothermal energy is a renewable resource that provides
heat from the earth - 'geo' means 'earth' and 'thermal' means 'heat.' You know
all of those volcanoes on Earth that spew hot lava when they erupt? That lava
has got to come from somewhere, right? It's actually sitting underneath the
earth's surface as incredibly hot rock and magma.
We find the most heat in places like plate
boundaries because these are like large cracks under Earth's surface where the
heat can escape as well as places on Earth where the crust is relatively thin.
Old Faithful and other natural springs and geysers are the result of geothermal
energy and that water can be hotter than 430°F!
Bio-fuels: are
renewable resources that are fuels made from living organisms - literally
biological fuels. Ethanol is a biofuel because it's derived from corn.
Biodiesel is vehicle fuel made from vegetable oil, and I bet you didn't know
that people can actually run their cars on used oil from restaurants! Firewood,
animal dung and peat burned for heat and cooking purposes are also biofuels
because they come from living (or once-living) organisms
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