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History of Energy Lecture Transcripts

Welcome to the first module of Global Sustainable Energy: Past, Present, and Future. And we're going to start the story like we say, in the past. This is the history of energy. In the beginning, we just had human power; whatever we could do in a day was what got accomplished. We carried things or used simple machines. How much work can a single human accomplish if you work all day? Well, for example, take a look at this picture here. There's a young lady carrying water in her village. That's a current picture, that's modern photography. So one of the things we'll look at is not only the past, but the fact is that many people around the world, over a billion still live on human power today, or simple machines.

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Before we get started, there's some things we have to figure out. This is a science based course, so we have to figure out what a unit of power, energy, what are these things that we, we deal with all the time and never stop to think about? But a watt is a unit of power, or energy per unit time. The unit of energy is a joule. You know, like scientists do, they always figure out something to name after themselves. Actually, they didn't, it's the people who follow on after them, they thought so much of the people, Watt, Joule, that they named units of power and energy after them. So a watt, when you look at it, is energy per unit time or a joule per second. So it's instantaneous rate, how much can somebody do at a particular point in time. Now if you look at an average human, If you work all day, an average human can work at a rate of 75 watts, or power output. Now that's an average human. That's not an athlete that's really in training and can jump and leap tall buildings in a single bound, or things like that, that's an average human. So let's break this down in units. A daily output is 75 watts, or joules per second, a watt is a joule per second. Now, if we convert that time, 3,600 seconds in an hour, we can get rid of that time in the bottom. And then, an average workday of eight hours, you can figure out the average daily output of a human, which is 2.16 megajoules were the M stands for mega or million. So 2.16 million joules per working day is an average human being.

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Now another way to look at that is something that some of us might be more familiar with is that the energy use if I save for instance a light bulb. So look at a 100 watt incandescent light bulb. Now this is before we get into the next module, so it's not an energy efficient light bulb yet. Let's look at the old fashioned incandescent light bulb, the 100 watt. Now how much energy would we use in a 10 hour period? Well 100 watts times 10 hours is equal to a 1000 watt hours. Now watch the units very carefully. This is where a lot of people get tripped up. It is not watts per hour, it's watt hours. It's on the same line. So if you look at the units, a watt as a joule per second. If we multiply this by ten hours with a suitable conversion, 3600 seconds per hour, the time cancels out so we're left with joules or energy. So when you buy a kilowatt hour from your utility, you're in effect buying a block of energy. That's all we're doing there, is buying a block of energy. So on a human scale, an output of seventy-five watts for eight hours, yield six hundred watts per day of 0.06 kilowatt-hours per day.

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So we worked this way for many, many years, just human power. And you know, I can imagine the first person looking over there after a long day at work and getting kind of tired and thinking to himself, man if I could just get this cow to work for me things would be a lot better. So that's what they did, they harnessed a cow, an oxen, a farm animal. Even before they had the farms they thought about domesticating and harnessing an animal to help human beings out. The problem is that early on, these early harnesses did not effectively transfer the power from the animal to whatever's being pulled. So the early harnesses made a cow or oxen worth about four humans. And at four humans, it wasn't worth the prevailing practice of just enforcing labor so what we did was that didn't change practices for many, many years. We still worked on that.

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So what happened next is that we come up with a better harness where the cow was worth about six human beings. At that point, domesticated animals really took off and we started harnessing simple machines. These, a picture right here is two donkeys, looks like from the ears, there pulling a disc harrow with the farmer sitting on a seat right there. So we tried to harness our animals to help us out. So let's take this further and make a, an example that kind of leaps forward in class a little bit. But just look at the US, for example; we spend and use about 18 and a half million barrels of oil a day in this country. Okay, and a barrel's 42 gallons. You find out that a gallon of crude oil's worth about 141,000 BTUs, or British Thermal Units. You can do that in mega joules also. But you break that down, do the proper conversions, and find out that, that oil consumption is worth about 2.43 gallons per day per person in the country. And if you look at that, I gotta look down at my notes here 'because I couldn't remember all these things at once stuck in my head. But that allocation of oil to each person in this country is equivalent to about 166 humans, output of 166 humans per day. So that would be like harnessing 166 laborers to do what you need to do, to have done during the day regardless of how you wanted it done, whether it was going to the store in your car, or air conditioning your house. But, in terms of comparison, that is, concentrated energy.

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But, if we look around the world, today, we still have many places in the world that use human powered activity and animal power activity for the vast majority of what they do in a day. Here's two oxen here pulling a plow on the left hand picture. On the right hand picture are two farm carts. You can see some of the modern technology, the rubber tires, axles, metal, but still, it's a farm animal pulling a farm to market type of cart.

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We progress in our history of energy, we started using wind power for things. This is a, a scene probably in the low countries in Holland where you use wind to pump water and to drain the land so you could farm it. And in the front you have a cart pulled by, it looks like a dog. So we harnessed, harnessed very many different animals to do our work for us over time. And now we move on to physical attributes of the planet we live on, like wind.

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The picture on the left is a, Jacobs Aeromotor the Great American Desert is what we called that originally when we explored that region in the United States of America, but we found out that desert actually had very, very good soils, and underneath the desert was a large aquifer. So we put these early wind powered pumps in there, to pump water out to provide water for our earlier farms and farm house uses. Now, an early version of that if you look on the right is a Persian wind mill. Now that Persian wind mill's probably 1500 years old, it's a vertical axis, different from the others and wind can only approach from one direction. That's in an area where you might have tradewinds that are very predictable, always coming from one direction.

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Water power was the next thing to be harnessed, where we have examples of water wheels being in use. There's an overshot, and I think the one the top picture there might be stream flow, where it's actually just the flow of the stream that causes the water wheel to work. And that can be used to saw wood, to grind grain, to provide power for many different uses.

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Time marches on. We can start putting these outputs in comparison to what we talk about in early human output. Early windmill mechanical outputs, about 1.5 to 10.5 kilowatts, early water wheel mechanical output is 1.5 to 3.8 kilowatts. Again, many, many times more than a single human could do during a day. Now, the wind power strange looking thing right next to my elbow, is a, guy by the name of Brush invented a windmill to produce electric, not wind mill, but a ind powered generator to produce electricity in 1888. The output was 12 kW, massive improvement, but still nowhere near what we do today.

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Now, use wind power, use water power, now somebody comes up with an engine, an actual mechanical engine. The first engine in production use was a Newcomen steam, steam engine in 1712. Newcomen developed a very simple steam engine that basically used an up and down motion to pump water out of coal mines. Didn't care about the efficiency, which was about 1%, because it's a coal mine. All you did was dig more coal out of the coalface and shove it into this pump to pump water out of the mine. Well, along comes Watt, again we named that unit of power after that, the watt. Along comes Watt, and his partner Bolton, who somehow in the tides of history have been forgotten, but it's the Watt/Bolton steam engine. Massive improvements in terms of separating the condensing and the heating part, so you have a cool part and a hot part. And they separated the two, so you could do them more efficiently and more quickly. Also, replace the up and down motion with a rotary crankshaft to give us rotary motion. Now rotary motion is important because the next thing you do with rotary motion, is start making things that can move.

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So, early power summary, we've got a working laborer, 0.075 kilowatts, an Ox, 0.45 Kilowatts, early wind power one 1.5 to 10.5, early water power is 1.5 to 3.8 kilowatts, Newcomen steam engine is 15 kilowatts, Watt/Bolton steam engine now 25 kilowatts. But the next thing on our ticket is a diesel engine, that's 10 kilowatts. So we're starting to move on to magnify human power.

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So let's see what these numbers mean in comparison to working laborers. So an ox is equal to 0.45 kilowatts, human being was 0.075. Simple division, back to our onversion. Six workers equaled about one ox. The largest early wind power devices represent the output of 140 laborers, 10.5 kilowatts to 0.075 kilowatts. The output of a Watt/Bolton stream engine was equivalent to about 333 laborers. Now, flash forward ahead to us, an automobile with about 134 horsepower engine, I picked that because that's equal to about 100 kilowatts, is equivalent to the output of about 1300 individual laborers. So remember that the next time you have to go back and get that gallon of milk that you forgot at the store. It's like harnessing 1300 individual laborers just to get you out to get that gallon of milk, that you forgot. So that's kind of a beginning of our early power summary, early energy summary. And the next module we'll talk about is agricultural energy.