Hello, back to Energy 101. And today we are looking at electric power

plant capacity factor. This is another major characteristic we

need to study, and be aware of when we're dealing with utilization of electricity

from the grid. And essentially, I don't know, 99% or

more, of our electricity comes from the grid.

That's the, basically a pool that has many power plants feeding into it.

Renewable energy photovoltaics, renewable energy, wind generators hydroelectric

dams, nuclear coal plants, gas plants, they all feed into the same grid.

And then at the other end, we pull out some electricity and the, the power plants

are turned on and off, and up and down, to meet our demand.

So but the demand varies. And so, what does the demand that's placed

on the grid, that the utility servicing the grid, and managing the grid, has to

deal with. Well time of day is an obvious one.

It, the peak demands, peak electricity usage is during the day.

And the lowest is at night. Two, three o'clock in the morning, most

factories are closed down, office buildings are closed down, homes are

closed down, people are asleep, and so the electricity usage is low.

Temperatures are low, by the way, and therefore even air conditioners are, lower

than the daytime, in the South, for instance, summertime.

So the air conditioners are unloaded even. But they all, it also changes by day of

week, that you might not think of at first, because weekdays, Monday through

Wednesday, have a higher demand, and have a different profile than weekends,

Saturday and Sunday. So, the, utilities have to be prepared to

operate differently on Saturdays and Sundays, and weekend days, than during the

weekdays, Monday through Friday. But they also vary may, in another major

way, and that is over a longer term, by seasons.

The Winter and Summer, have a higher demand than the Fall and the Spring.

And of course the reason for that is, the Fall and the Spring have a low heating

need for the space heating, when the temperatures are, are 70 degrees, or the

are fairly comfortable outside, that we have to provide less space heating for our

buildings, and our homes, than we do in the Winter.

And in the Summers, we have to provide air conditioning, in the Summers, for space

conditioning. Fall and the Spring, we don't have to

supply as much air conditioning. So, you have variations, short term

variations, from hour to hour in the day, daily variations from day of week, and

seasonal variations with Winter, Summer, Fall, Spring.

So the su, utility managing the grid, has to deal with all of these ups and downs,

and be able to meet the highest demand that people ask for, when they turn

something on, and they also have to throttle things down, when the dam, demand

is low, because there's no electrical storage system.

Electrical storage is very expensive and it isn't commercially viable at this

point. Hopefully it will be in the future, but

electricity can, is, can only be generated if people use it.

So everything's gotta match up. Let's, talk, look at this a little more

closely, and before we do that, we need to look at some definitions.

Power capacity of a power plant, or a fleet of power plants, either way, is the

maximum steady power production capability.

Maximum being the running wide open as they're designed to do.

It's not like the car trying to run it wide open at a 120 miles per hour, and you

probably can't do that very long before you damage something in a lot of cars.

But these are, this is industrial equipment that is designed to operate with

maxium power, rated power, in a, steady state, for days, or months on end.

That's the maximum, capacity, or what we call the power capacity.

Now that's like speed on your speedometer. In other words, it's measured in Mega

Watts, which we denote by MW, and we or Kilo Watts, which is denoted by Kilo

Watts. Of course, a Mega Watt is a million Watts,

and Kilo Watt is a 1000 Watts. And that's the rate at which we're using

the energy. Like miles per hour on your, in your car.

And it's the, we denote the maximum capacity, that the power plant, or the

fleet of power plants, if it's to look at all of them feeding into the grid, we

denote that by MW, capacity, subcapacity, or Kilo Watts of capacity, just depending

on whether you want which units you want. Ones just a thousand different than the

other. So that's the power capacity that, and so

and, that needs to be of course higher, a little bit higher, than the maximum demand

that the system will ever see. Otherwise we have blackouts and brownouts,

and equipment gets overloaded and the system falls apart.

But, another definition, that we'd like to look at, is the electrical energy

production. That's comparable, using the speed analogy

on, in a car, to the miles analogy. If the power that we're using, times the

time we use it, that gives us the energy used, that determines how much fuel we've

got to put in and how long we have to run the plant, and how hard we have to run the

plant. So in other words, it's the electrical

energy used typically, we always say, over one hour.

So it's measured in Mega Watt hours, MW hours, or Kilo Watt hours, KW hours.

And that gives us the amount of energy that is used over some period of time.

And for, pow, Capacity factor, we generally look at a whole year.

And so the, the annual load factors determined by the looking at the annual

electrical energy production over years, denoted by Mega Watt hours per year, or

Kilo Watt hours per year. Typically Mega Watt hours per year,

because there are a lot of Kilo Watt hours that are produced over a year, even by one

power plant. So those are the basic definitions.

Moving, further on definitions, what are the, the capacity factor, which is the

whole point here, in discussing, is to find, as the Mega Watt hours that is

produced in one year, and this is for one power plant, if you looked at the capacity

factor of a power plant, or through a whole fleet of power plants feeding into

the grid. You can do it nationally, you can do it

for just a, a region or one utility that and, one part of the grid that has, is

under control by one utility. Then that is divided by the Mega Watts

capacity, that, that, that the power, power, plants are capable of, pro,

producing, if they run wide open, times 8760 hours.

Now whats the 8760 hours? Well, 807, 8760 hours, is the number of

hours in a year. So, in other words, if the plant, the

denominator, is the number of Mega Watt hours that the power plant, or fleet of

power plants, could produce if they ran wide open, to, at rated maximum capacity,

for every hour of the year. So that's what the denominator is.

The numerator is, of course, the actual amount that is produced.

So that, the number is always less than one, due to the fact that the capacity has

got to be equal to the maximum demand put on the system, over the entire year.

And that many period, most periods of the year, and hours of the year, the demand is

going to be less than that. So, it's not producing, fully, every hour

of the year, so the numerator was going to be less than the denominator.

So, it measures electricity produced as a fraction of the electrical energy it could

have produced by running maximum, output every hour of the year.

So that's the definition of the capacity factor.

By the way, let me note here, that there's also a term that you, some of you might be

familiar with, called the load factor. And, in the load factor definition, the,

there's a small difference, hopefully small.

In most cases the meh, denominator is not Mega Watt capacity, but the peak load seen

throughout the year. And the power plant capacity needs to be

slightly greater than the maximum load at the system, or power plant ever sees

during the year in order to stay 10% higher.

In order to maintain control of the, and be able to keep from going unstable, for

stability purposes. So some nuances there.

But capacity factor, and load factor, are very similar, except the capacity factor

will always be a little bit lower than the load factor, because the used Mega Watt

peak demand during the year Rather than the Mega Watt capacity of the system.

So, let's look at an example there. Well, let's take a nuclear power plant.

Nuclear power plants, I picked that one because that one has the, largest,

highest, capacity factor. And take a large, two unit, typically,

they're built in thousand Mega Watt units, and if you take a two unit nuclear plant,

that has the capability of producing 2,000 Mega Watts on a continuous basis, that's

the capacity. And let's assume that they, you measure

the actual output over, of that plant over the year, and it was 15 million Mega Watt

hours. That's the actual energy is produced.

But it could produce how much? It could produce 2,000 Mega Watts times,