Can you imagine life without television,
cars, or computers? What if you had to cook your dinner over a
fire or fetch water from a river? It might be fun for a camping
trip, but you probably would not want to do it every day. But
that's how life was before scientists and inventors discovered
ways to use energy to make our lives easier.
Today, most of the energy we use
comes from fossil fuels. Coal, oil, and natural gas are all fossil
fuels. Over millions of years, the decay of plants, dinosaurs,
and other animals was formed into fossil fuels. These fuels lie
buried between layers of earth and rock. The only way to get them
out is to drill or mine for them. While fossil fuels are still
being created today by underground heat and pressure, they are
being consumed more rapidly than they are created. For that reason,
fossil fuels are considered nonrenewable; that is, they are not
replaced as soon as we use them. So, we could run out of them
sometime in the future. Or, we might someday use so much fossil
fuel that we won't be able to drill or mine fast enough to keep
up with the demand.
Because our world depends so much
on energy, we need to find sources of energy that will last a
long time. What if there was a type of energy that never ran out?
There is. It is called renewable energy.
In addition, because there are so many people on the earth using
fossil fuels, we create a lot of pollution. So, we should also
use energy sources that produce as little pollution as possible.
While all energy sources cause some pollution in their creation
or their consumption, renewable energy systems generally are less
polluting than fossil fuel systems.
Renewable energy systems use resources
that are constantly replaced and are usually less polluting. Examples
of renewable energy systems include solar, wind, and geothermal
energy (getting energy from the heat in the earth). We also get
renewable energy from trees and plants, rivers, and even garbage.
Did you know that wind is considered an indirect form of solar
energy? This is because the wind is driven mainly by temperature
differences on the surface of the earth that are caused by sunshine.Now,
people use the wind to generate electricity. The windmills built
long ago had many blades, but today's wind turbines usually have
just two or three blades that turn when the wind blows. The blades
drive a generator that produces electricity, much like steam turbines.
Read more about wind
The water in rivers and streams can be captured and turned into
hydropower, also called hydroelectric power. The most common form
of hydropower uses dams on rivers to create large reservoirs of
water. Water released from the reservoirs flows through turbines,
causing them to spin. The turbines are connected to generators
that produce electricity.Hydropower
is also inexpensive, and like many other renewable energy sources,
it does not produce air pollution.
However, the drawback to hydropower
is that damming rivers can change the ecology of the region. For
example, the water below the dam is often colder than what would
normally flow down the river, so fish sometimes die. The water
level of the river below the dam can be higher or lower than its
natural state, which affects the plants that grow along the riverbanks.
When you burn a log in your fireplace or in a campfire, you are
using biomass energy. Because plants and trees depend on sunlight
to grow, biomass energy is a form of stored solar energy. Although
wood is the largest source of biomass energy, we also use corn,
sugarcane wastes, and other farming byproducts.
There are three ways to use biomass.
It can be burned to produce heat and electricity, changed to a
gas-like fuel such as methane, or changed to a liquid fuel. Liquid
fuels, also called biofuels, include two forms of alcohol: ethanol
and methanol. Because biomass can be changed directly into a liquid
fuel, it could someday supply much of our transportation fuel
needs for cars, trucks, buses, airplanes, and trains.
We can use the energy in sunshine to warm and light our homes,
heat our water, and provide electricity to power our lights, stoves,
refrigerators, and other appliances. This energy comes from processes
called solar heating, solar water heating, photovoltaic energy
(converting sunlight directly into electricity), and solar thermal
electric power (when the sun's energy is concentrated to heat
water and produce steam, which is used to produce electricity).
Read more about solar
We can also get energy directly from the heat in the earth. This
is known as geothermal energy, from "geo" for earth and "thermal"
for heat. Read
more about geothermal energy
Energy from wastes
What you may throw out in your
garbage today just might become fuel for someone else. That's
right, whether you call it trash or garbage, this municipal solid
waste has the potential to be a large energy source.
Garbage is also an inexpensive energy
resource. Unlike most other energy resources, someone will collect
garbage, deliver it to the power plant, and pay to get rid of
it. This helps cover the cost of turning the garbage into energy.
Garbage is also a unique resource because we all contribute to
energy in your future
One day, all your home's energy
may come from the sun or the wind. You may not think twice about
filling your car's gas tank with biofuel. And your garbage might
contribute to your city's energy supply. As scientists push the
limits of renewable energy technologies and improve the efficiencies
and costs of today's systems, we will soon be to the point when
we may no longer rely mostly on fossil fuel energy.
USA - Department of Energy
Energy Efficiency and Renewable Energy