I find it valuable to explain and for people to understand the ultimate source of the energy that they use. Sometimes, it's not always obvious. So, we're going to go through a chart of photographs which illustrate different types of energy. We're going to talk a little bit about for each where that energy ultimately came from. In this slide, we see a number of pictures as I said. The top left one is a picture of Niagara Falls. So, it's a waterfall like you'd find anywhere else in the world, and that we talked about potential energy. So, the water at the top of the falls has potential energy to do work. So, as it falls down. If it falls down the waterfall, all it's going to do is generate heat in the water below it, and then that heat is gone forever and we've lost the opportunity to take advantage of it. But where do the energy of Niagara Falls or any other waterfall in the world come from? It's not immediately obvious. But actually, it's solar energy. So, the sun causes evaporation in various places, creates water vapor. We get precipitation of that water in a different location at a higher altitude, and then we see the waterfall coming down. So, if we didn't have the sun, the great lakes would drain and every other water system would drain, and we wouldn't have any water coming over waterfalls anymore. So, we look at it as hydropower. But its really sunlight at some level. So, the figure to the right of that is a series of wind turbines. Where does the wind come from? We think of it as a renewable source wind. But where does wind actually come from? Well, it comes from differential heating of solar, again on the surface of the planet. So, some areas get a lot of sunlight and the air rises and we see engineless planes taking off and soaring with thermals. If we place these wind turbines in the right place, we can take advantage of its torque and unpredictable winds and harness some of that energy. But again, we're looking at wind and the ultimate source of wind is the sun itself. So, the picture to the right of that is a picture of Three Mile Island, a nuclear facility that got some fame years and years ago for an accident that they had. So, what's really going on in a nuclear plant? We find fissionable materials. We bring them to a nuclear plant. We arrange them in a particular way. We generate heat. We use that heat to make steam, and then the steam turns the turbine, and we get electric power out of that. So, what's the ultimate source of that? Is that the sun in anyway? Well, no. These radioactive compounds have been around forever. We dig them out of the ground, purify them, and bring them in. So, it's a unique form of energy that does not come from anywhere else other than radioactivity itself. Let's go to the second row, and we're looking at a piece of coal in the first picture on the left. What is coal? We dig it up out of the ground. It produces 40 percent of the electrical power in the United States. It tends to go down. It used to be up to 50 percent not long ago. There's a lot of political concerns about digging coal and the amount of carbon dioxide that's produced from it. China has a lot of coal power plants. So, where do coal come from? Well, if a tree falls in the forest and lays on the ground. Can you come back 300 million years later and find a piece of coal in its place? No. Why? Because there are microbes and there are other processes and the presence of oxygen which basically turn that piece of wood or plant matter into carbon dioxide in a relatively short period of time, maybe even five or 10 years. But if organic matter is trapped underground in the absence of oxygen, interesting processes occur, and we get coal. Particularly, if it's been submerged in the earth. As we all know, when you go further into the earth, things get warmer. So, that is a slow cooker for a lot of petrochemicals. Coal is the inevitable result of that. Something between 250 and 300 million years old, we can now dig up coal and use it. But what does it really? Well, this was plant life at one point. So, in a very real way, I want you to think of coal and a lot of other things as stored sunlight. This is sunlight that existed on the planet Earth 250 or 300 million years ago, and is now being harnessed out of the ground and burned. So, think of coal and a lot of other things as stored sunlight. I think it's a different perspective, one you don't hear a lot. But in a very real sense, it's true. Now, let's look at the geothermal properties of Yellowstone National Park in the picture just immediately next to it. The interior of the earth is pretty hot. We use that for geothermal heating. Some places, it's so prevalent. They actually use it to make electricity with. Some people use it to warm their homes or supplement the warmth in their homes or to cool them, if the ground temperatures are cool. But where does the heat in the inside of the planet actually come from? Well, it turns out, and not a lot of people appreciate this, it comes out from radioactivity. So, in the beginning of the universe, there was radioactive compounds, and they're trapped in the earth, and they decay. As they decay, they generate just a little bit of heat, and it gets trapped inside the center of the earth. I read a curious article once and they were saying that well, these are radioactive compounds. We're going to run out of them eventually, and the center of the earth will cool. That sounds like something we should be concerned with. But then they said by the time that occurs, the Sun will have turned into a red dwarf and consumed the planet Earth. So, we really don't have all that much to worry about the cooling of the earth. It's going to take a long time. But, it's interesting to note that inside of the earth is warmed by radioactive compounds largely. Next picture over is oil. That's how we get oil out of the ground. If you've driven around the western end of the United States, you've seen these along the side of the road. Much like coal, oil is a form of stored sunlight. This is sunlight that hit the earth many years ago and got trapped as petroleum, and now, we're pumping it out of the earth. So, we are in this particular time in the industrial revolution, discovering these sources, and unleashing the carbon that was stored many, many years ago using the energy of the sun. So obviously, the sun is getting pretty important to us as we consider the sources of energy we have here on the planet. Let's go to the next one, that's a solar panel. Obviously, that's using the sun's energy. While it only represents one-and-a-half percent of our electrical generation at the current time, it's an important one-and-a-half percent. The technology is catching up. Efficiency is increasing. Cost of production is lowering. We're getting a fantastic return on that. Moving to the bottom row is liquid natural gas ship. That's very characteristic ship by those spheres that are located on the ship. Chances are you've never seen one because they're not welcomed on the coastline all that much because they represent a security hazard. But that's how you move liquid natural gas. Now, why do we put it in the special ships? Because we're taking natural gas or methane, and we're compressing it. It's pretty cold. It's 275 degrees below zero, and it's at about a concentration of 600 times. So, the volume that that gas might have taken is now 1600th. So, there's a lot of methane or natural gas in the ships. Now, the United States used to be a net importer of natural gas using these ships we got a lot from Trinidad and other places, some in Africa. Just in the last couple of years, we have become an energy exporter of liquid natural gas. So, there are limited facilities where we can compress this fuel and put it on and board the ships and send it around the world. But it does represent the future of what we're going to do with methane that we get out of the ground from hydrofracking. We'll talk more about that later. So, but once again, liquid natural gas is methane. Where does methane come from? Again, stored sunlight from a very long time ago that comes off the ground. We'll talk about more about where methane comes from in the ground. But just to know, it's again sunlight. So, ethanol is represented by the corn that's grown in that next picture. As you all know, we grow a lot of corn in this country for food and for energy. If you look at the pump you see, it's got a 10 percent ethanol rating on it. That's all comes from corn. That is a direct byproduct of the sunlight striking those plants. So again, except for the next picture and all the ones with radioactivity, we're really looking at the role of the sun in providing us energy. So, that brings us to the last picture, and there's a bunch of ships there. They're in a coast. The further you move away from the equator, the larger the tidal change is. I believe this picture is someplace up in Nova Scotia where the tides can be rather large. So, these tides represent the movement of a lot of water in a cyclical way. Twice the day, they move in and out of their harbors. There are people who are putting the equivalent wind turbines under water to try to harness the movement of all that water. Other people are trying to trap the water and create a waterfall scenario where you can return it, and water back to the ocean turns a turbine. So, where does the tides come from? Where does all this energy come from? Well, it comes from the gravitational pull of the moon. So again, not having to do with sun or radioactivity. A whole new source of energy. That's just the gravitational pull of the moon creating an opportunity for us to try to figure out how to make use of that energy.