Alternating Current
Almost all electricity we create is “Alternating Current” or AC. We’ve all heard things like 120 Volts AC @ 60
Hertz (or 50 Hertz if you are chilling on another continent). AC simply means the current is constantly
swapping back and forth from positive to negative. Image you had a fish tank and were shaking it
back and forth so that a wave was going back and forth 60 times a second (yes
your arms would get mighty tired). We
then fix a ball which can go up and down in the middle of tank at the surface
of the water. This up and down motion of
the ball is what we are trying to harness when we use AC electricity. For heavier balls we would need to shake our
arms harder or use more water. Making a
ball move up and down may not seem like the most efficient use of our energy,
but now let’s imagine that coming out of the front of the ball is a rod, and
this rod is attached to one end of an old water pump. As we shake back and forth, the ball goes up
and down, the pump fills and expels water and now we are cooking. With this stream of water we can get up to
all sorts of hijinks.
Producing
AC Current:
To make AC Current we need two
things from our example, Boundaries and the Energy to move these boundaries
back and forth. The water in the example
is electrons, the little guys that move around to transfer the energy, and the
ball is whatever we are plugging into the outlet.
For boundaries we are going to use large, strong magnets. Magnets by themselves will not cause the electrons to move they simply tell them where to go. They are like the tank in the example. They will force the electrons back and forth once we start to introduce energy. Due to how magnets and coils of wire interact the energy we need to put into the system is to spin a coil of wire between the magnets. As we spin the coil the electrons start to go back and forth and an AC current is caused. The more coils of wire and the stronger the magnets the more electricity we make. We now have a goal – take something large spin it about an axis.
We have been spinning things
around an axis since the wheel was invented.
Any type of engine you can imagine can be used to generate AC power –
combustion, coal, steam, water, hand crank (Unbreakable
Kimmy Schmidt style). Your
classic power plant is basically a giant fossil fuel eating machine. Large engines spin large coils around and around. The rest of the plant is concerned with
regulating the voltage and current coming out of it, but for the sake of this
blog we can pretend a traditional power plant is a huge car engine and the only
thing it is driving is the alternator. No matter your opinion on fossil fuel
exhaust, the traditional power plant produces a ton of it.
The primary way we spin stuff
around stuff is steam. Unlike a
combustion engine we aren’t exploding anything to spin the engines but heating
water or gas to create steam. Tremendous
pressure can be created to then spin a turbine, spinning a coil, creating
electricity. The simple steam engine
uses coal for fuel. You light it on
fire, place it under some water and it burns for a long time; we have been
doing it for forever. Coal has
questionable emissions and a huge lobby behind it. Clean coal… also has questionable emissions
and a huge lobby! Recently natural gas
has taken up the flag alongside coal as our largest electricity producing
fuel. Similar to boiling water on your
stove, you just burn the natural gas to create heat and boil water or gas to
create steam.
66% of our Electricity is estimated to come from burning Coal (30%+), Natural Gas(30%+) and Petroleum (1%). 90% of all coal produced in the US went to electricity in 2016.
66% of our Electricity is estimated to come from burning Coal (30%+), Natural Gas(30%+) and Petroleum (1%). 90% of all coal produced in the US went to electricity in 2016.
The much harder way to create
steam is nuclear power. That’s right, the end goal of a nuclear power plant,
which uses the sum of all human knowledge from the beginning of time until now,
is to create the same thing your gas
stove cane make. A nuclear reactor
utilizes nuclear fission (topic of another post) to create heat. The important take-away of nuclear fission is
that it produces a ton of energy, once started uses very little fuel and
creates waste we have no way currently
of getting rid of. Newer and newer
reactors are being designed which either create very little waste, or can
re-seed old waste to reuse as fuel.
These are what the fossil fuel lobbies are fighting against. I could spend the rest of forever talking about
how I feel nuclear power plants will become Americas new “New Deal” but I’m
trying to wrestle my bias into submission.
20% of our Electricity is estimated to come from Nuclear Power.
20% of our Electricity is estimated to come from Nuclear Power.
Finally we use nature to make AC
power. Naturally occurring sources of
energy like wind and water can be used to turn generators. We have been using dams and wind turbines for
a long time. Their advantages are free
fuel and little to no environmental impact.
Their disadvantage is they are limited in location by the existence of
the naturally occurring energy. You
cannot create a dam where there is no moving water; you could put all the wind
turbines in the world in Camden County, NJ and would be better served hand
cranking your generator.
6% of our Electricity comes from Water power, and 5% from Wind.
6% of our Electricity comes from Water power, and 5% from Wind.
Direct Current
Direct current or DC, unlike AC
is “one direction”. It is much more like
pushing water through a hose. At the end
of the hose is a ball we want to move. If the ball is heavier we either need to
increase the pressure of the water, increase the width of the hose to let more
water through or both. It’s pretty easy
to see the appeal of DC; if I want to move the ball forward I point my hose at
it and shoot; no intricate system of
energy exchanges as seen in our water tank example. For this reason (and others) we use DC to drive
pretty much everything. Your appliances,
car, electronics, are almost all all DC circuits. “Liar!” you say! “My house has AC coming into it from the
street and you just spent 10 minutes telling me that all of our Electricity is
AC”. Producing DC is difficult and
expensive. It is much easier to shake
the tank back and forth and lose some energy along the way than constantly push
water through the hose.
Generating DC current:
The DC current producers we are
most familiar with are batteries.
Batteries utilize chemical reactions to create a constant flow of
electrons. To compare to our analogy,
the chemical reaction would be the water pressure required to push the water
through the hose. New batteries are
constantly being researched and advertised however think about how often you
have to recharge your iphone or laptop.
The amount of energy needed to put back into the system to create DC
power via chemical reactions is just too high to be commercially viable, which
is why we only use it for portability’s sake.
What if the energy to recharge DC power cells was free though? This is what solar panels attempt to capitalize on. The sun can provide energy that is not only free but also unlimited and incredibly powerful. They utilize the light of the sun to stimulate electron flow. The power is then used to recharge batteries to provide constant current (the sun isn’t always out), or converted to AC power and used as before. For a long time solar faced all types of setbacks. Solar panels were difficult to make, expensive and so inefficient it did not make sense to use them for anything aside from small power and academic reasons. This has become less and less true as more and more research has gone on and they are now much more competitive.
Next Two Posts: Natural Causes of Climate Change -- Crash course in Electrical Engineering
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