33. Energy Resources, Renewable Energy

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RONALD SMITH: Well, we’re going
to finish up the course by talking about energy. It’s one of the primary–our
need for energy is one of the primary ways that we interact
with the environment, both draw resources from it,
but also influence the environment. So I think it’s a fitting way
to end up the course. Today I’ll probably just
get through these two. Although, so I’ve put hydropower
down here and renewable for the future. But it’s a big player today. So I’ll probably talk about
hydropower today. But the rest will be discussed
mostly on Wednesday. Now, over here, then, is the
cartoon that will kind of remind us where everything
fits in this picture of energy resources. Hydroelectric comes from rain
falling on high ground, so it has potential energy. If it falls at sea level,
you can’t get any hydro energy from it. But if it falls at a high
altitude, you’ve got that potential energy to draw from. The sun, through photosynthesis,
will allow plants to grow. And then you can use
that biomass in several different ways. Direct conversion of solar
to, say, electricity. The differential heating from
the sun, as you know, can create the winds. And the winds can turn
a wind turbine. The winds also produce
waves on the ocean. And those waves can be used
to generate electricity. The heat from the sun also
creates a temperature difference within the oceans. If the thermocline is there,
you’ve got warm water above and cold water below. And that temperature difference
can be used to derive a kind of renewable
energy. The moon and the sun, their
gravitational pull on the earth, produce tides. And that can be tapped
for energy. Everything else comes
from down within the interior of the earth. Oil and gas in the ocean bottom
comes mostly from algae that grew, or phytoplankton
that grew in the ocean millions of years ago and then
fell to the bottom and got covered over. Coal, oil, and natural gas on
the continents came from ancient biomass that
got covered over. Geothermal comes from the fact
that the interior of the earth is hot. And sometimes those hot rocks or
hot lava can come up pretty close to the surface. And then that temperature
gradient can be used for renewable energy. There is also uranium in the
crust. In fact, some of this geothermal heat comes from the
natural decay of uranium. But we can also dig up that
uranium and use it in a nuclear power plant. What have I left out? Is there anything, any
renewables you can think of that I don’t have on there,
or any form of energy not included there? OK, let’s start to go
through this then. So first of all, we have to
remind ourselves about units. You guys are good at this by
now, so I won’t spend much time on it. But the SI system of unit
of energy is the Joule. The unit of powers
is the watt. Energy is power times the time
over which you are using it. So a watt second is a Joule. And inversely, power is
energy per unit time. So a Joule per second
is a watt. However, when we’re talking
about electricity, there is a non-SI unit that is
quite standard. And that’s the kilowatt hour. So the watt is an SI
system of unit. And we’re used to putting
a prefix on it kilo meeting 1,000. But then the time unit is an
hour instead of a second. So that kind of messes up the
SI system a little bit. But it’s easy to go back and
forth, because as you know, there are 3,600 seconds in
an hour, 60 times 60. And therefore, one kilowatt
hour is 3.6 megaJoules. And you don’t have
to memorize that. Just remember how many seconds
there are in an hour. You can just work that out, that
correspondence, anytime you need it. But it’s odd, because
it’s an energy unit. It has a power times a time. So it’s a little like this,
except we end up not with Joules, but kilowatt hours. And if you’re an economist and
you want to have something to remember about this unit
kilowatt hour, well, it’s about $0.10 per kilowatt
hour when I pay my electric bill at home. It varies by a factor of two
or three across the country however, so that’s not
a fixed value. Any questions there? Now, it is convenient to break
up our use of energy into three general categories. I think you’ll appreciate this
as we go through the material. Although it seems a little bit
odd in the beginning to break it up in this particular way. We use energy for heating,
heating your home, for example, just to raise
the temperature. It’s a very kind of low-tech
way of using energy. In fact, it’s the lowest form
of energy when you’re just using heat to raise the
temperature of something. Transportation, moving
goods or people. You can use gas in your car
for that, or diesel fuel. And then electricity, which
is a very broad category. It includes electric motors,
lighting, electronics. But you can also use electronics
for heating and for transportation. So electricity is a very
broad category. But it’s a much higher form of
energy in a sense that I’ll be describing later than just
raising the temperature by adding heat. So we’ll see how well that
three-part categorization works for us as we go through. And then, of course, there’s
all these energy resources. These are the ones that I put
on the cartoon over there. I’ll just run over them briefly
here and make a few additional comments. And we’ll be going through most
of these in some detail today and tomorrow. Coal. There’s lots of it. It is rather heavily polluting,
puts a lot of CO2 in the atmosphere
by burning coal, oxidizing it to form CO2. Oil and natural gas. There’s less of it than coal. It’s less polluting, both
in terms of local air pollution–that is to say, less
sulfur, less mercury, generally less ash also, it’s
at about 20% less CO2 emissions per Joule of
energy than is coal. So it’s better in almost every
respect than coal, except there’s less of it. Nuclear plentiful, mostly
non-polluting. Certainly, it puts no CO2
in the atmosphere. Waste storage is a problem, and
public resistance because of a danger factor with
nuclear plants. Hydroelectric falls into
the renewable category. Clean, it’s limited, and you
lose natural rivers and ecosystems when you dam up large
valley systems. There is a technology, though, called
run-of-the-river hydroelectric, where
you don’t dam it. You just take the flow that’s
there on any particular day to put through your hydroelectric
plant. That avoids the big dam, the
big reservoir, and avoids a lot of the loss of natural
rivers and ecosystems. So you can do hydroelectric
without damming up. But it’s not usually done. Wind is renewable, moderate
cost. A lot of people don’t like to look at windmills. So there’s public resistance
to it. Also, sometimes there
can be noise and issues about bird kill. Solar renewable, high cost.
Also, some people don’t like to see the landscape covered
with solar panels. Ocean waves and tides haven’t
made very much progress. It’s renewable. It’s very high cost to build
something that’s going to sit in the ocean and move around
and draw energy from the waves and tides. The engineering really
isn’t there yet. And biomass. Renewable, polluting if you
burn it, but no net CO2 because you’re drawing in CO2
from the atmosphere to make the biomass. And then when you burn it,
you put the CO2 back. If you’re only putting the CO2
back, it wouldn’t be too bad. But you’re also putting in ash,
probably some mercury, other things along with that
burning of the biomass. Any questions there? All right. So that’s our starting point. Now, this diagram takes a
bit of getting used to. It’ll be in the, of course,
in the lecture you’ll have on the server. But I’ll go through it. It’s from the year 2006. And it’s US per capita energy. And the units are in watts. So it’s the rate at which
we’re using energy for a variety of different purposes. And I’ll run through some of
it, but I won’t go through every detail. So here’s oil, biomass,
coal, natural gas. Obviously, oil, coal, and
natural gas are the bigger inputs here. There’s geothermal, wind, hydro,
nuclear, and solar up at the top as well. Now, they’ve got a separate
branch at the top for electricity production. Everything that’s going to
be used by first making electricity goes up to
this top area here. And we see that a little bit of
oil is used for that, but a lot of coal. In fact, almost all the coal
that’s used in this country is used for making electricity. A lot of natural gas, some
geothermal, wind, hydro. All the hydro is used
for electricity. All the nuclear is used
for electricity. All the solar is used
for electricity. Of the 4,400 watts per capita
that’s used for electricity production, 3,000 is lost as
waste, energy waste, usually in the form of heat. And about 1,400 is used for
residential, commercial, industrial, and even a tiny
bit for transportation. So you see how the
diagram works. And then over at the right-hand
side, it has brought together all the waste
from the different energy streams and put them up here,
and then brought together all the useful energy and
has categorized them here in the green. So you can read this by sources,
by use, and by this last category of waste
or useful work. Questions there? Yeah? STUDENT: Is the wasted energy
wasted in the process of getting the energy, or is it
wasted like when you leave a light on in a room, and
you’re not there? PROFESSOR: Mostly, I think this
diagram is meant to include all of that. For example, it includes
transmission loss. If you have a power plant
where you’re making electricity, and then you have
to send it over power lines to get it to the consumer,
there’s going to be loss in that. And then there’s going to be
some–if you’ve got a motor running, but some of that energy
goes into heat instead of turning the shaft of the
motor, that would be lost. But I think it would also include
your category, which is lost in the generation of
the electricity. Yeah, good point. So we’ll be going back
to look at this dominance in fossil fuels. We can see it here. But we’ll look at it again in
other ways in just a moment. So electricity consumption per
capita, remember this was USA. To put that in a somewhat
broader context, let’s look at that quantity for various
countries. So this is per capita
consumption of electrical energy. And United States is here. I’ve put the arrow
there to show it. It’s about 1,300 or 1,400
watts well, no, this is kilowatt hours, sorry kilowatt
hours of energy used per year, yearly. And we are a high user. But there are higher users. Why would Iceland, Norway,
Finland, and Canada use more than we? STUDENT: Heating? PROFESSOR: Sorry? STUDENT: Electric heating? PROFESSOR: Electric heat, yes. They do a lot of electrical
heating. First of all, they’ve got a lot
of electricity from hydro in those countries. So the electricity cost
is pretty low. Generally, heating with
electricity’s kind of a waste of a high form of energy. But in those countries where you
have a lot of electricity, you can heat your
house with it. And they do. And that gives them a very
high per capita use of electricity. Now, we heat our homes, too. But we do it more from natural
gas, from oil. And so the heating we
do would show up in a different category. It wouldn’t show up in the
electricity consumption. And compared to other countries,
however, we are pretty high in our
electricity use. Questions on that? And of course, these things have
been growing over time. So we’ve got a green band, a
red band, and a brown band renewables, nuclear, and
fossil since 1980. And this is annual electricity
generation worldwide. It’s not per capita. So the unit is large. It’s a terawatt hour per year. A terawatt hour per year. Remember, it goes kilo-,
mega-, giga-, tera-, in powers of three. Terawatt hour. So nuclear has grown. But is steady the last 15, 20
years, renewable here is almost all hydro. Almost all the other renewables
we’ll be talking about in this course, at the
moment, are pretty tiny. And so the only one that really
shows up on a graph like this is hydroelectricity. And then the fossil fuel has
been growing, unfortunately. And that’s the big
CO2 producer. So I’ll stick–let’s start with
coal and see where that is and how we use it. There are the global
coal deposits. I’ll keep my comments to the
northern hemisphere. China has quite a lot. Russia has the largest
of any country. Europe has quite a bit. And the United States has
quite a bit of coal. Zooming into the US, you see
that there are coal beds along the Appalachian Mountains, some
in the Midwest, and some in the Rocky Mountain West.
They’ve sub-categorized it here in terms of different
quality of coal. But I’m not going to
go through that. I’m just going to show
you generally where the coal is located. So if you want to generate
energy and you live in this part of the world, you’re
probably going to find coal is the cheap way to do it. But maybe if you’re over here,
you’ll find a different method because you’re pretty far
from the coal beds. How do you use coal? It’s very simple. You burn it, you generate
steam, you put the steam through a rotating turbine. The rotating turbine’s hooked
up to a generator. The generator makes
electricity. You’ve got to cool that water
off on the downside of the turbine, so it doesn’t
give back pressure. And putting gas back in the
wrong direction, you’ve got to have cooling as well. Very simple idea. You just make steam and put
it through a turbine. However, when you burn, of
course, you’re going to generated–you’re oxidizing
carbon. You’re going to generate CO2. There’s some sulfur
in the coal. You’re going to generate SO2. There’s some mercury. You’re going to generate
HGO and NOX. Where does that come from? Well, remember, you’re
burning this coal in the presence of air. Air has N2 and O2. If your flame is hot enough,
you’ll dissociate N2 and dissociate O2, and they’ll
recombine NO. And then you’ve got
a pollutant. So these are coming
from the fuel. The carbon was in the fuel, the
sulfur was in the fuel, the mercury was in the fuel. This is not coming
from the fuel. This is coming from air
that you’re using to oxidize the coal. You’re basically dissociating
air and forming NOX. And then the particles are
coming off the smoke. Remember that, because some
other ways for generating heat will generate NOX even if
there’s no pollutant in the fuel itself. So when you see a power plant
like this, those are the smokestacks. That’s where the combustion
products are going to be leaving. And that’s the cooling tower,
where you’re cooling that steam on the backside
of the turbine. So that is not smoke. That’s just water vapor
condensing to form a cloud there. And they have enough scrubbers
on the stack that you’re not seeing much of a smoke plume. But there is some coming off
of the smokestacks there. So know what you’re looking
at when you see this. You know what you’re
looking at here. Long trains full with boxcars
with coal transport the coal from the mines to
the power plant. And you see the big piles
of coal ready to be put into the burners. Now, there’s this useful
quantity called the emission coefficient, which is how much
CO2 do you put in the atmosphere for every Joule
of energy that you create electricity. And so the units here are CO2
emission coefficient in units of kilograms per gigaJoule. Kilograms of carbon dioxide per
gigajoule of electrical energy produced. And different types of
fuel is given here. The coals are generally
in this region. And they are high, generally,
about 95 kilograms of carbon dioxide for every gigaJoule
that is produced. The oils, burning fuel oil,
is about 20% lower. And some of the natural gases
are even 20% lower than that. So they’re still putting CO2
in the atmosphere, but at a rate that’s maybe 30 or 40%
less than coal does. So coal, in this measure, is the
worst. And of course, in the local air pollution,
it’s also the worst of all of these options. And what is the future
of coal? So here’s a timeline, 1950 up
to 2100, 90 years from now. The units are megatons
of coal. And it’s broken down by
different parts of the economic world, North America,
Europe, the Pacific countries, China, South Asian countries,
and the former Soviet Union. Look at some of these
characteristics. So North America has peaked
and is going to be flat according to these
projections. Europe peaked long ago and is
now down to a fraction of what it was using 30 or
40 years ago. China is rapidly increasing
at the moment. Of course, these are
projections. We don’t know exactly what
they’re going to do. But it looks like they’re going
to dominate coal use. They do already. It looks like they will
continue to do that for 20 or 30 years. And then they’ll probably
run out of coal. The former Soviet Union, which
remember that big blob up in the right-hand side of
that earlier diagram? We’re talking about that. And they’re not using
much of it yet. But that’s probably
all of this. So 50, 60 years from now, they
will probably be the dominant user of coal. Any questions on that? Yeah? STUDENT: So the decrease over
time for all of these regions, is that because of a change in
energy use, or is it because they’ve run out of coal? PROFESSOR: I think it’s mostly running out of coal. I don’t think these projections
that are put forward put much stock in the
fact that we’re going to purposely leave that stuff
in the ground. Yeah. There’s this term you hear on
television all the time “clean coal.” I can’t tell you how
many times I’ve seen this commercial. Maybe I listen to the wrong
channels or something. But “clean coal” is a marketing
term used to indicate coal burning without
local air pollution. And to some extent, that is
feasible today with the appropriate scrubbers on the
smokestacks, but also with carbon capture and
sequestration. The term “clean coal” usually
infers both of these. But this second technology
is not developed yet. So it’s talking about
something really far into the future. So there is no such thing as
“clean coal” if, by that term, they mean both of these
characteristics. So watch out for this term
“clean coal.” It’s a little bit of a figment of the ad
agency’s imagination. So then we’ll talk briefly
about oil. Where is the oil? Well, I hope you can read
that in the back. But most of it’s in the Middle
East Saudi Arabia, Kuwait, Iran, Iraq, and the Emirates. And so that’s just what
we know about from the newspapers, right? That’s the cause of all
of our headaches. The oil comes from the Middle
East. But there is quite a bit in the USSR, Venezuela. The United States doesn’t
have much left. A few other countries have it. This is as of this moment. And what does it look like
into the future? This goes to 2050 and starts
in the year 1930. And it’s in units–strange
units, billions of barrels per year. GB/A, gigabarrels per annum,
is the unit on that thing. And this brings us to this
concept called “peak oil.” The concept of peak oil is that oil
use will, at some point, reach a maximum and then begin
to decrease slowly. And it’ll do that–it’ll peak
at different times in different countries for
different reservoirs. For example, the US has probably
passed its peak oil. It probably did it 10
or 20 years ago. Other countries, for example,
the Middle East, won’t reach their peak oil or maybe they’re
just about reaching it these are all projections,
though, so they can’t be trusted. But eventually, they will all
taper off because you’re using up the resource not because
you’ve decided to keep it in the ground, but because you’re
using up the resource. So by the time we get to 2050,
we’ll be already halfway down from the peak. And of course, the price at that
point will be climbing even much more steeply
than we see today. Remember, the coal curves
went further than that. That plot went out to 2100, of
course, just in the former Soviet Union. You should know that New
Haven is a big oil port for New England. Here’s a Google picture of
the port in New Haven. And all these white circles
here, of course and there are dozens of them are oil tanks. So when you drive across the Q
Bridge and look around, you’ll see these things all
over the place. And of course, that’s because
the oil tankers come in there, off-load their oil into these
tanks, and then they are transported by truck to the rest
of New England, used for a variety of purposes. Some of it’s gasoline, some
of it’s crude oil. Among other uses is that it’s
used to drive the Harbor power plant, which is here, I guess,
which gives us most of our electricity in New Haven. There’s the power plant. It’s called the Harbor
Generating Station. Last year, it emitted almost
600,000 tons of CO2 into the atmosphere, while producing
about 600,000 megawatt hours of electrical energy. Yale produces a little
bit of its own. But this is the main generator
plant for New Haven. This information and a lot more
comes from a nice website called that tracks
fossil fuel burning plants around the world. And you can get information on
how much they burn, how much CO2 they put in the atmosphere,
and so on, from that interesting website, Questions here? Natural gas has suddenly
become very important. These are the areas where we are
currently getting natural gas or we’ll soon be getting
large amounts of natural gas. And they use this curious word
“play” in the natural gas industry to indicate an area
targeted for gas development. So if you run across that
word, don’t be confused. It has that particular term
in that field of study. And it’s a very exciting field
right now, because they’ve learned how to get–suddenly
they’ve learned how to get natural gas out of
shale, using this method called fracting. So when you look at the
timeline, this is similar to the ones I’ve shown you for coal
and oil, except it’s for natural gas and just
for the US. And the timeline is a shorter
one, 1990 to 2035. They’ve got these various
categories tight gas, onshore conventional, offshore,
coal bed methane. But look at this new
one, shale gas. It was almost nothing. And then just a couple years
ago, they discovered this method for getting natural
gas out of shales. And suddenly, that’s become
the biggest one. And it’s growing. So this is a big surprise. It humbles us in terms of our
ability to predict the future of energy resources, because we
didn’t see this one coming. And temporarily, this is going
to really shake the markets and is shaking the markets,
and is, to some extent, slowing down the development
of renewables, because now we’ve got a cheap new source of
natural gas, which, as they say, is cleaner than coal. However, it’s still a fossil
fuel, still putting CO2 in the atmosphere. Questions on this? OK, we’ll move on to nuclear. That’s what a typical nuclear
plant looks like. These are cooling towers. You don’t see any smokestacks. You’re not burning anything. You’ve got the reactor core. You produce steam from that. And the rest you know. Once you get the steam, you
put it through a turbine, turbine runs a generator
to make electricity. You’ve got to cool down the back
side with cooling water. That’s what the cooling
tower is for. And then you can recycle
the water. Now, remember, this is
nuclear fission. This is taking large nuclei and
splitting them apart to get energy. This is a book you’d find, in
an introductory textbook in nuclear physics. It’s the binding energy per
nucleon as the function of the mass number of the element that
you’re talking about. It has a peak roughly where iron
sits, and decreases to the right and the
left of that. This means that if you split
apart heavy nuclei, you can get energy out, or if you
combine like nuclei, you get energy out. That’s called fusion. This is the way the sun makes
its energy, by taking hydrogen and hydrogen and
making helium. And this is the way we make
energy in a conventional nuclear plant, by taking uranium
235 and splitting it apart into lighter nuclei and
getting energy out that way. We’re still working on a way
to do this synthetically. That’s one of the great unsolved
problems in nuclear physics, is how to make a
fusion reactor that’ll generate electricity for us. We’ve been trying for 50
years, still haven’t been able to do it. So all the nuclear plants we’re
talking about here use fission to generate
electricity. Questions on that? These are the countries that do
it, ranked by the percent of their total electricity
generation that is done by nuclear. Lithuania and France lead
the way with 75%. The United States is over here
with 22% percent, and so on. So we are not a leader
in this by any means. But we do some. And here’s where the
uranium is located. The big purple box for each
country just gives you a measure of how much uranium is
believed to be stored in the earth’s crust within the
national borders of each of these countries. So we have a lot. Canada has a lot. Kazakhstan has a lot. Russia has some. Australia has a whole lot. What about Connecticut? Yes, we get some of ours
from Connecticut. There’s a nuclear plant in the
southeast corner of the state called Millstone 2
and Millstone 3. That’s what it looks
like from the air. And it generates about 2,000
megawatts of energy. But it has a sad history
in a way. The install capacity, in terms
of gigawatts, is given here. And the number of reactors is
given here, 100, 200, 300. And you see that it grew rapidly
during the ’70s. But then because of these two
famous incidents Three Mile Island in eastern Pennsylvania
and Chernobyl in the Ukraine suddenly, people got
spooked about the use of nuclear plants. And really, nothing much has
been built for the last 20 years, even 25 years, in terms
of new power plants. So that is a large build-out. But it’s pretty much flat for
the last couple of decades. And what to do with
the nuclear waste? So I mentioned that there was
a plant–there’s a nuclear plant in southeast
Connecticut. There used to be one up on the
river, up on the Connecticut River, in the center
part of the state. That’s called the Connecticut
Yankee Plant. That was shut down about
15 years ago. And not only did they have
nowhere to ship the waste, the nuclear waste when that plant
was active, but when they stopped the plant and
decommissioned it, they still had no place to put the waste. So it’s still sitting there. 15 years after the plant was
shut down, you still have all the nuclear waste below ground
in these big tubes, because we don’t know yet in this
country how to get rid of nuclear waste. So that’s a real problem. Questions on that? I think we can get through
hydro then. The basic idea is
a simple one. For hydroelectric power, as I
said before, you need to get the water falling
on high terrain. Now, that’s likely to happen
anyway, because when the air comes along and lifts up over
a mountain, you cool the air adiabatically, generate clouds
and precipitation. So you’ve got this process
called orographic precipitation, mountain-induced precipitation, that
automatically gives you a lot of rain on high terrain. So it’s kind of perfect
in a way. The potential energy, then,
you’ve produced is the product this is right out of your
physics textbook potential energy is the product of mass,
gravity, and height. It’s simply Mgh. And that would have units
of, well, Joules. Now, your job is not done. You’ve got to get this into your
hydroelectric plant, get it through a turbine, and make
electricity from it. But at least the energy is there
from the rain falling on high ground. And as I mentioned before, it
can be either a dammed up lake, or there are these new
run-of-the-river designs, where you don’t have to dam,
you just take the water. But then you’re subject to
whatever the river flow happens to be at the moment. You don’t have any way
to store and use it during dry periods. So there’s a typical
dam system. This is from Hydro-Quebec
up in northern Quebec. A large dammed lake goes down
through a power plant, generates electricity,
off you go. Here are some examples. I’ll show you some of these
in just a minute. The James Bay Project, up in
northern Quebec, generates 16,000 megawatts when it’s
operating at full capacity. The famous Grand Coulee Dam,
about 7,000 megawatts. These are all the most famous
dams in this country. Hoover Dam’s 2,000. Glen Canyon’s 1,300. And the Three Gorges dam, the
new one that opened up in China about 10 years ago,
is the largest of all. That’s about 20,000 megawatts. Let’s take a look at these. So the James Bay Project
is here. Do you know where you are? So here’s Labrador. Connecticut’s down
here somewhere. And Hudson Bay is here, and
James Bay is there. So they dammed up some of these
rivers on their way into James Bay and Hudson Bay. A word about the seasonality
of hydroelectric. And I’ll use Hydro-Quebec as an
example in my discussion of seasonality. As you know from this course,
rainfall normally comes heavier in some seasons of
the year than in other seasons of the year. Well, in Canada, for reasons
we’ve already touched on, the maximum demand is in winter
because of electrical heating. And yet, in winter, most of the precipitation falls as snow. So it doesn’t go right
into the rivers. So the maximum natural river
flow is in the spring and early summer from snow melt. So how do you solve
that problem? Your demand is in winter. Your natural river flow is in
spring and early summer. Well, there are two
ways to solve it. One is the obvious way. The reservoirs can store that
water for six months until you need it. And the other thing is to sell
it to a place that has a different demand curve. In other words, they sell a lot
of energy to us down here in New England, because a lot
of our maximum demand is in summer for air conditioning. So using those two methods,
they solve this incompatibility between
their demand and their natural river flow. So as you go around the world,
not only for hydro, but for the other renewables, you want
to look at this issue. When is the demand? When is the source available? And find out some way to
solve that problem. That applies to almost every
renewable energy source. The timing isn’t what
you would want. Questions on that? Another famous one is the
Columbia River and the Snake River that feeds into it. So here is Washington
and Oregon. The biggest–there are a lot
of big dams along there. I think the biggest is a Grand
Coulee Dam, which is there. And that’s the one I gave you
the production numbers for. Another big area in this
country is the Colorado River system. And the two most famous parts
there are the Glen Canyon Dam with Lake Powell backed up
behind it and Hoover Dam with Lake Mead backed up behind it. But on the scale of things,
those are relatively small. Those are those numbers there. I mean, they look majestic
to see them. But they’re not as large a some
of the other big, new hydroelectric plants we
have around the world. And then the Three Gorges Dam
in China, you see it here, backed up a huge lake. And that has that huge number of
20,000 megawatts of energy at full capacity. How does it work? Well, you’ve got your reservoir
with a certain height of water. Hydrostatically, that generates
high pressure at the bottom, which pushes water down
through this smooth tube called the penstock, smooth to
avoid turbulence and losses. And then it goes right
into the turbine. And then the rest of
the story you know. You turn the turbine, the
turbine turns a generator, which makes electricity. And off you go. And the water then goes
on down the river. There’s the Grand Coulee Dam. And I want to show you this. There’s a couple of people
standing there for scale. There is the turbine, one of
the turbines for the Grand Coulee Dam. These are really massive
turbines that generate a lot of electricity. Yeah, so let me just wrap
up with this then. I pulled off this data from
the DOE a few years ago, comparing three states
Connecticut, Ohio, and Oregon. Now, Connecticut, as we’ve seen,
has some petroleum and gas being used to generate
electricity. But it also has a big
nuclear component. In fact, that’s the largest
single component. 44% of our electricity in Connecticut comes from nuclear. And our CO2 emissions, on
average, are pretty low because of that. Ohio doesn’t have too much
coal of its own. But West Virginia lies
just east of it. It shares a long border with
West Virginia, which is a strong coal-producing state. And so they ship the coal over
the border, burn it. And 86, 87% of the electricity
in Ohio is generated by coal burning. Oregon, on the other hand,
being on the West Coast, mountainous, heavy rainfall,
81% is hydroelectric. So here, within the same
country, within the US of A, because of the way these
states are located in different provinces, you’ve got
three completely different dominant electrical energy
sources hydroelectric, coal, and nuclear. So there is a lot of variability
out there. And it depends on what’s
available nearby, basically. Any questions on this? That was a lot. Let’s finish it for today. And on Wednesday, we’ll
do the renewables.

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