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 overfishing, 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!
Biofuels 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.
Non-Renewable
Resources
In
contrast to renewable resources, non-renewable resources are
resources that are not easily replenished by the environment. Let's think about
this in terms of that ice cube maker again. Imagine that this time you don't
have an automatic ice maker at home, you have to wait for someone to bring it
to you, and they only do this once a month.
If
you used up all your ice quickly, it wouldn't regenerate in your refrigerator,
and you would be out of ice until the next delivery comes. The same thing
happens with non-renewable resources on Earth, except the wait time is much
longer than a month - usually more like thousands or millions of years!
The
fuels we use to heat our homes and drive our cars are non-renewable resources
because there is just no way that the earth can regenerate them in a usable
time frame. Minerals are also considered non-renewable resources because, not
only do they take millions of years of heat and pressure to form deep
underground, but they're also found in a very limited quantity on Earth. Not
all non-renewable resources are usable only once, though.
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