Hello, we're going to dive a little 
deeper into the second law of energy 
conversion today. 
we are covering the energy conversion 
section where we're dealing with energy 
converting from one form to another. 
And the laws of nature that we have to 
abide by in order to make that 
conversion. 
And the, whereas the first law talks 
about energy in has got to equal energy 
out. 
We can't create or destroy total energy. 
This one has to do with the value of 
energy if you recall, that when I just 
summarized it very quickly. 
That is like even though you have a pound 
of gold and a pound of lead, they have 
different values. 
Well, if you have one kilojoule of work, 
and one kilojoule of thermal energy, they 
have the same energy but they have 
different values in most cases. 
value from a thermonamic value, and 
interestingly enough, the thermonamic 
value ties with economic value. 
work and electricity will cost, if you're 
trying to buy it, will cost you a lot 
more than natural gas, for instance, to 
produce heat. 
So when we say value, it's not just 
thermodynamic but also economic value, 
Many things have what we call a quality 
that we arbitrarily assign to them of 
one, which is the highest quality. 
Work, electricity, kinetic energy and 
radiation all have a quality value of 1 
and then we downgrade anything that has 
quality value less than these to some 
lower number than one. 
and work of course we, we produce it with 
a power plant. 
Electricity we produce it with a 
generator, kinetic energy, wind turbine. 
I hadn't talked about this one. 
wind turbine of course, takes the kinetic 
energy out of the air. 
Or extract some of it, not all of it. 
And extracts the kinetic energy from the 
wind and uses that kinetic energy to 
rotate a shaft to turn a generator to 
produce electricity, which a wind farm 
does. 
Radiation we produce, use that radiation 
energy from the sun to produce 
electricity with a solar cell. 
and then we have thermal energy. 
That one, thermal energy is the oddball 
here as unfortunately are just a fact 
that most of our energy comes from fossil 
fuels which we burn the fossil fuels to 
produce thermal energy or heat. 
In order to get the energy out of. 
So most of the energy conversion 
processes that it, somewhere along the 
line involves thermal energy that we've 
extracted or heat or we've extracted from 
burning fossil fuels, and that value 
vary, of that energy, that thermal energy 
or heat, varies with the temperature Of 
the object that, has that heat or thermal 
energy. 
And, of course, combustion is what 
produces the high temperature that has, 
that has the high thermal energy. 
now, unless this is a rather complicated 
slide, but let me, let me just walk 
through it with you here and number one, 
the thing we want to notice is the 
vertical scale of high up has higher 
quality and low down. 
On the bottom, has 0 qualities. 
So we go from 0 quality energy to high 
quality energy of 1. 
And, you know, if you've got 3000 degrees 
fahrenheit, you're somewhere right here. 
The lower the temperature, the lower the 
quality is. 
So Quality and temperature go together. 
Here's temperature on the shown scale on 
this side and the quality value on that 
side, but high temperature increases the 
quality of the thermal energry. 
and work and electricity of course are up 
here, they're up there with a quality of 
one. 
That's the work and electricity which is 
the most valuable in things we have to 
pay the most for when we want them. 
The the lower temperature examples of the 
lower temperature thermal energy. 
That we want and use, is cooking. 
Cooking doesn't have to be at five, 3000 
degrees Fahrenheit obviously. 
We burn everything. 
But cooking is not so high temperature. 
Hot water for our showers is only around 
30, 40 degrees Centigrade. 
And 100, 110 degrees Fahrenheit. 
space heating is very low, relatively 
speaking. 
So you're talking about a house that's 
maintained at 22 degrees Centigrade or 72 
degrees Fahrenheit. 
And, when the outside temperature is, 
maybe, 0 degrees centigrade or 32 degrees 
Fahrenheit, so that that is low quality 
energy, which is good if that's what we 
need because it's cheaper and easier to 
get. 
The lower the quality is of the energy or 
the thermal energy in this case The 
cheaper it is, and the easier it is to 
get and convert and produce. 
and at ambient temperature, we have zero 
quality. 
Now, here's 1 thing we have to 
understand. 
There's a lot of energy in the ambient. 
Air. 
The molecules in the air are bouncing 
around and that will with thermal energy 
at ambient temperature. 
So there's a lot of energy there. 
A lot of energy. 
But it has no value, has no value. 
I'll give you a quick story I, a, 
[UNKNOWN], sheet rock we call it here in 
the U.S. 
Sheet rock manufacturers came to me one 
time and wanted to help him, or take a 
project to deal wall boards that makes up 
the inside wall of houses. 
And put something in the wall boards that 
would. 
Take the energy out of the ambient air, 
and produce electricity to drive the 
house. 
And he was convinced this was the grate 
idea. 
As a matter of fact when I told him I 
couldn't do that and it violated all the 
laws of nature. 
He actually went to the president of the 
university and he had to be the vice 
president of marketing and tried to force 
me to, to take it. 
But you can't, can't violate the laws of 
nature. 
so there's a lot of energy in the ambient 
temperature air. 
But it has no value. 
Has zero value. 
Zero quality over here at ambient 
temperature. 
They go together, even though there's a 
lot of thermal energy there, there's not 
anything you can do with it, nothing you 
can do with it. 
So, you can study this in a little bit 
and again, high temperature, high quality 
up here, low temperature Zero quality and 
decreasing value. 
you have .1, .2, .3, .5. 
You go on up the scale and energy value 
as you move on up to a higher and higher 
temperature. 
combustion flames have pretty high 
temperature and have pretty high quality 
of the thermal energy in that flame. 
Let me. 
Okay, so here's, here's what the second 
law of thermodynamics tells you, you 
cannot do. 
There's a big X here, tells you, you 
cannot do it. 
I cannot, no one can. 
Cannot take low, quality in here. 
Again, this is high quality. 
It's vertical in the highest part of the 
scale and, and low quality is the bottom 
part of the scale of the graph. 
I put heat in at a low temperature. 
You could even say, well I'm going to put 
it in an ambient temperature. 
And I'm going to convert it 100% on a one 
on one basis to electricity of work. 
Does not violate the first law of 
thermodynamics. 
I put in one unit of energy here and I 
get out one unit of energy there. 
So I have not created or destroyed 
energy. 
But the second law of thermodynamics will 
not let you do that. 
Why won't it let you do that? Why does 
gravity pull down? I don't know. 
We just observe the laws of nature and 
don't try to figure out why the universe 
was made the way it was. 
but this is, the, one of the reasons the 
2nd law is so misunderstood, is it's one 
of the very few laws, as a matter of fact 
as far as I know, the only one. 
And that is totally stated as a negative 
statement. 
You notice that the first law is energy 
in has got to equal energy out, because 
you cannot or destroy it, total energy. 
But this one merely says what we cannot 
do. 
Well, when we stop and think about it, 
there are an infinite number of ways to 
make a negative statement. 
I'll give you one of the, the most 
obscure ways that you hear connected to 
the 2nd law alot. 
And that is, the [INAUDIBLE] of the 
universe cannot decrease. 
Well, that, that's a true statement, but, 
it doesn't give me many, much intuity of 
understanding what the 2nd law says you 
can or cannot do. 
But you hear many, many, many different 
statements of the law, all of them 
negative. 
And onto the equivalent you can prove any 
accurately stated negative statement of 
the second law from any other. 
Any negative statement of the second law 
could accurately state it can be proven 
from any other. 
And so that's one reason that intuitively 
it's a little bit harder to graph. 
And it's certainly is not intuitive that 
you can't do this, let me give you a very 
fundamental example. 
If I have a hot cup of coffee, if I have 
a cup of coffee and it's at room 
temperature, I bring it into the 
classroom and I set it down, and it's 
cooled down to where it's ambient 
temperature, 70 degrees farheinheit or 21 
degrees centigrate, and and I say I want 
a hot cup of coffee. 
Well, there's nothing that says that some 
process won't Cool the ambient air down a 
little bit and put that thermal energy 
into the cup and make the cup hot, hot 
coffee. 
That would be increase in the quality of 
the thermal energy in the coffee, but it 
won't, can't happen. 
You've never observed that to happen, 
it'll always cool down. 
We can go from high quality energy to low 
quality energy very easily and as a 
matter of fact, the universe moves in 
that direction. 
but we cannot go from low quality energy 
and up to high quality energy with no 
other net effect. 
With no other net effect. 
And notice, there's nothing else going on 
here. 
1 unit of energy, low-quality thermal 
energy coming in, and I have high quality 
electricity at work, 1 unit coming out. 
Nothing else going on, it cannot happen. 
That's 1 statement of the 2nd Law of 
Thermodynamics. 
What can we do? Well, let me get rid of 
this, my writing here. 
What can we do? Well this is what a auto 
engine, an auto engine, a diesel A deisel 
engine or a, or a electric power plant, 
does, this power system represents any, 
any one of those. 
And what does it do? Well we put in 
combustion energy into the plant, we 
drive it with, and drive the engine with 
gasoline that comes from oil or we drive 
the deisel with deisel fuel or drive a 
power plant with natural gas or coal. 
And we put it in, we put 3 BTU's in. 
Notice it's not 0 quality though, it's 
not 0 quality, it has some quality 
because it's, it's at a relatively high 
temperature. 
We can produce high quality energy, but 
to do it we've got to degrade Other 
energy, some of it. 
We cannot do it. 
We cannot have 3 BTUs going in, and 3 
BTUs coming out as electricity. 
We can have 1 BTU of en-, of electricity 
coming out, and 2 BTUs coming out at 
ambient temperature that we are rejecting 
to the river, with a quality of zero. 
So if you're going to upgrade. 
From part of the energy, I've got to 
downgrade the rest of it. 
I cannot upgrade all of it. 
So I can only upgrade it if I use the 
downgrading of, of, of some section, some 
segment of the energy to drive the 
upgrade. 
And that's what an auto engine, a diesel 
power, diesel engine or power plant does. 
And this is maybe a little difficult to 
grasp, but is 1 thing, by the way I've 
had people and read articles where 
engineers are really stupid because we're 
throwing away 2/3's of our energy to the 
river. 
We need to be using. 
Well, that would be great if you could do 
it, but the second law of thermodynamics 
will not allow you to convert all of this 
combustion energy into electricity. 
You have got to throw a lot of it away at 
zero quality, or a low quality close to 
zero. 
If you're throwing it away to the 
atmosphere of the river. 
It is a 0 quality. 
So there's, a, people say we're throwing 
away all this thermal energy at ambient 
temperature, and we need to recover it 
and do something with it. 
It has no value just like the ambient am, 
molecules in the air have lots of energy 
as they bounce around, but they have no 
value. 
We can't do anything with them. 
That's just the laws of nature. 
Okay. 
that's a very quick overview of the 
second law of energy conversion. 
Which is highly misunderstood, or not 
understood at all by a lot of, lot of 
people and a lot of our Population. 
Which is not surprising. 
when we look at it, we see that it's not 
very straightforward. 
To understand, particularly from an 
intuitive concept. 
Why you have to do it the way we have, 
nature says we have to do it is not clear 
at all. 
But why does gravity pull down when i 
jump out of a building, I fall down 
rather than going up. 
That's just how the laws of nature are. 
Okay, thank you.