Energy Conversions In a Power Plant

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Here in this diagram we’re
looking at how a basic power plant works. A power plant generates
electricity. And it burns fuel and produces
or converts first the chemical energy that is there in the
fuel here to heat energy. And that heat energy or thermal
energy is converted to mechanical energy over here. And mechanical energy is
converted to electrical energy in this generator. So basically a power plant is
divided into three components. The first component is boiler
here, which burns the fuel, coal, oil, natural gas, or any
fuel, and produces the heat. The water that is going
into this boiler boils and becomes the steam. This steam, at high pressures
and temperatures, has a lot of energy, kinetic energy. And this energy basically comes
into this turbine and turns this turbine wheels. And we use this high-pressure
steam to do that. And this high-pressure steam
gives up the energy here and then turns into low-pressure,
low-temperature steam. And this one turns. This turbine one turns. This turbine is hooked
up to a generator. This generator is nothing
but a magnetic field. In other words, that magnetic
field is created by these poles, north and south. And these yellow ones are,
basically, the magnets. And in between these two
poles, this electrical conductor, a copper wire, which
is turned many rounds across or around an
armature, turns. The two ends of this wire are
hooked up to a load or to a transmission line. So when this conductor is turned
in a magnetic field, you get the electricity,
all right? To turn this conductor, we
are using this turbine. Because both of these
are hooked together. Once this moves, this moves and
generates the electricity. To move this turbine, we need
high-pressure steam. To produce this high-purchase
steam, we need thermal energy or a fuel, coal or oil
or natural gas. And that’s how these conversions
are taking place. Now, let’s get to
this turbine. The high-pressure steam, after
turning this turbine, converts into low-pressure,
low-temperature steam. That steam is sent
to a condenser. This is the condenser, which has
cold water on the outside. When the steam is going through
this cold water, this steam turns into water
or condenses. That is the reason we
call this condenser. And this low-pressure steam that
is condensed into water is put back into the
boiler, which, again, turns into steam. And obviously, when we convert
or when we turn this steam into water, that energy
is coming into this cooling water. And this water turns
into warm water. And this warm water is, again,
sent all the way up to this cooling tower. The purpose of this cooling
tower is to cool the water that is condensing the steam. So this is not simply
like a shower head. There are almost hundreds and
thousands of shower heads at the top of an almost 10-story
tall building. And when these droplets fall
down, what happens is the air that is going across this or
around these small droplets picks up the energy from
these droplets. And hot air goes out. And cold water comes down. Basically, almost about 30%, 40%
of the energy that we put into this device is actually
dumped out into the environment into the atmosphere
through this condenser or cooling tower. That is the reason this turbine
part is notoriously inefficient and boiler part
is pretty good, actually. It’s about 90% efficient. This is about 40% efficient. But once we turn this thermal
energy into mechanical energy, conversion into electrical
energy is pretty efficient, which is about, roughly, this
generator efficiency is almost 95% efficient. And as I said, this turbine is
only about 40% efficient. And this boiler is roughly about
89% to 90% efficient. So of all the three components,
this is the lowest efficient or least efficient
component. And this is the most efficient
component with 95% efficiency. That’s how a simple
power plant works. One other point that I want to
make is when we burn this fuel, of course, this thermal
energy is going out here. That is one type of pollution. And when we burn these fuels
here, the gases that are produced here are emitted
through the stack. And this is where the chemical
pollution or the pollutants are emitted into
the atmosphere. This is of concern for all
of us in a power plant.

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