Welcome back to our sustainable future. In the first three modules of the course, we covered issues such as global warming and subsequent climate change, social inequity, and the problem of wealth inequality, and some of the reasons why all of this is more or less part of our economic system; from the way that we've set ourselves up to live from day to day. Of course, if you're taking this course, you already know that in order to create a more sustainable future, we'll need to make some changes. While many out there equate the word changes with giving things up, most of the time, we'll be talking about shifting from doing things one way to doing them in a more socially and environmentally friendly way without having to give up anything, though non-economics might be a good place to start. Who doesn't love donuts? In this module, we look at the way we produce energy today, meaning burning fossil fuels such as coal and natural gas to produce electricity. We'll start by learning what we mean by fossil fuels and where they come from. We then turn our attention to how we get electricity by burning those fossil fuels in a power plant. We'll go into how a power plant works so that you'll understand what the coal or natural gas is actually doing in the process of producing electricity. Once we understand how power is generated, we can then dive into the relationship between how electricity is produced from, say, coal, and the quantity of greenhouse gases that are created as a result. This will be a useful thing to know as we evaluate our own energy usage and therefore our own contributions to greenhouse gases. Because once we know our own energy baseline, we can then think about the changes we need to make to reduce our own environmental footprint. Now, any discussion of energy needs to include nuclear energy. This is certainly a highly controversial issue as there are many pros and cons to nuclear power plants. We'll go over a few of those so that you can make up your own mind if nuclear energy needs to be in the mix for the future. Finally, we'll end on a bright note that many positive changes are already taking place when it comes to transitioning to power generation technologies that are inherently more environmentally friendly and even cheaper than what we're doing today. Our job is to help accelerate these changes and be a part of the growing movement towards a sustainable future. Let's get started. Let's begin with a brief overview of how most of the world gets its energy today with fossil fuels such as coal, oil, and natural gas. Coal and natural gas dominate the fuels used to generate electricity in ways we'll describe in the next few lessons. Oil, on the other hand, is a fuel that is mostly used for transportation, meaning gasoline and diesel fuel for our cars and trucks. As we'll shortly see, these fuels were formed from plants and animals over millions of years, which is why they call them fossil fuels. Because they literally take millions of years to transform from plants into fuels, we can't wait around for the next batch of fossil fuels to show up. That's one way of saying fossil fuels are non-renewable. There is only so much of them buried in the earth. When they run out or they become so scarce that they become too expensive, that's it. Let's start with how coal is formed. Millions of years ago, actually about 350 million years ago, there was a lot more water on the planet. Trees and other plant life that lived near the water would live their lives, die, and end up submerged in the swampy surroundings. Because they were underwater, oxygen wasn't available to do what it normally does to dead plants and trees, which is cause them to naturally decompose and return back to the soil. Without oxygen, the material decays differently and tends to stay intact as this gelatinous mark. If you've ever picked up a leaf that's been at the bottom of a pond for a while, you know what I'm talking about. Over time, ever increasing amounts of sediment covered these decaying materials, leading to the formation of very high pressures and very high temperatures. These pressures and temperatures chemically converted the carbon in the decaying plant and tree matter into peat, the first stage in the coal formation process. After a few more million years, the peat gets converted into something called lignite, otherwise known as brown coal. After a lot more time under high pressure and temperature, the lignite then transforms into bituminous coal or soft coal. Keep going and you get anthracite, a hard, shiny black carbon-rich material often used in steel production. There are plenty of deposits of lignite and bituminous coals, and once you dig them out of the ground, you can do quite a lot with them. Over the last few centuries, they provided a lot of heat; such as when people would heat their houses with coal-fired furnaces to heat the hot water for those radiators that we've seen in our grandparents and great grandparents homes. But beyond heating our homes, lignite and bituminous coal had been used to fuel the power plants that produce electricity, especially those plants in the 20th century and the early part of the 21st century. How do you get to the coal? Depending on the proximity of what is known as a coal seam relative to the surface, two general techniques are used. If the coal seam is close to the surface, then strip mining is often used whereby you strip away the surface layer to get to the coal and then just keep on going as you can see in the photo here. In hilly regions such as the Appalachian Mountains in West Virginia, there is another technique known as mountaintop removal, which is exactly what it sounds like. You essentially remove the mountain top to get to the coal underneath. Yes, this is also as dramatic and environmentally unnerving as it sounds. But where there is coal and people willing to buy it, people can get creative in mining it, even if the environment is drastically changed forever afterward. If the coal seam is much deeper underground, then underground mining is the technique most often used. While we may still have visions of coal miners with pickaxes going deep into the mine to chop out the coal along the walls, most of the time, large-scale operations involve huge mining vehicles with tools that aggressively grind the walls of the mine and collect the coal they get from it. Yes, there are still a lot of coal miners around, especially in developing countries, where they might still have pickaxes, but in modern coal mines, machines do most of the heavy lifting. What about oil and natural gas formation? Well, it's similar to coal with a few twists. Once again, we have to go back a few 100 million years where there was a lot more water around. In this case, all marine life, including plants and animals would live their lives, die, and then sink to the bottom of the ocean. Over time, meaning a few million years, these too would get covered with sediment. As the sediment layer got thicker, the pressure and temperatures on the decaying plant and animal matter also increased. After a few more million years or so under such high temperatures and pressures, the carbon and hydrogen that was in the decaying matter is converted into oil and natural gas. Now the nice illustration on the far right is a good simplification of the oil and gas reservoirs that form. In many cases though, at very high pressure, the natural gas is actually dissolved in the oil. Much like carbon dioxide is dissolved in a carbonated beverage, but hang on to that idea for a minute. People have been using oil from reservoirs like these for thousands of years as it turns out. But in 1859, near Titusville, Pennsylvania, a well was drilled rather than dugout. The first time drilling was used to get to a reservoir. This turned out to be an exceptionally efficient way to extract the oil, and that pretty much launched the modern day petroleum industry. Around the world, and in particularly in the Middle East, large reservoirs were discovered, and with ever-improving drilling techniques, it was easy and therefore cheap to get at all that oil. Some have remarked, it was like sticking a straw on the ground and letting the oil just bubble up all on its own. As we said in the last slide, the gas that tends to co-exist in the reservoir is often dissolved in the oil as the whole reservoir is under high pressure, but once the oil is up at the surface, the gas separates just like a shaken soda bottle. In the early days, no one really knew what to do with all that gas, so they just flared it onsite using large burners. But eventually, we figured out that the gas was pretty valuable and could be used to heat our homes, cook our food, and make a multitude of chemicals and innovative materials such as plastic. So the industry developed techniques to separate the gas from the oil at the well site, store the oil in large storage tanks, and transport the gas along pipelines. As you might expect, as the world's use of oil and natural gas grew exponentially, there's that growth curve again. We started to run out of those easy to drill and easy to extract reservoirs. We had to go deeper and in more remote locations to find new reservoirs. Drilling is now conducted in pristine parts of Alaska and even out in the middle of the Gulf of Mexico, where oil rigs have to drill miles below the ocean floor, which is already a mile below the ocean surface. Now that's an engineering FEED all by itself. Unfortunately, in such challenging drilling locations, when things go wrong, it usually leads to catastrophic results. As we found out with the Deepwater Horizon disaster back in 2010, which some of you might remember. Eleven people lost their lives, and the latest estimates suggest that more than 200 million gallons of toxic black crude oil leaked into the Gulf of Mexico. The worst spill in history, killing billions of fish, birds, and other marine life. The oil ultimately made its way to the Gulf Coast, which devastated the local fishing industry and pretty much ended tourism in the area for years. Once again, our need for energy comes at a steep price. In the latter half of the 20th century, it was learned that large quantities of oil and gas were locked up in the tiny pores of a rock called shale. We actually have a lot of shale here in Colorado where I live. The problem is you just can't drill a hole and get the oil out like you could with a reservoir. The oil and gas industry had to make several major technological breakthroughs in order to make that possible. One breakthrough was known as horizontal drilling where during the drilling process operators could actually guide the drill to make a 90-degree turn, and then go along the shale rock that contained all the oil and gas. The next breakthrough is one I'm sure you've heard about, hydraulic fracturing or fracking for short. In this process, large amounts of water, sand, and chemicals are sent down the well and into the shale rock region. Then under high pressure, the water, sand, and chemicals essentially break up the shale rock thus the term hydraulic fracturing. That releases the oil and gas which then flow up the well pipe, and is separated into the oil and gas constituents which are finally stored or sent down pipelines respectively. Now from an engineering viewpoint this process was pretty ingenious, and the industry made great leaps to make sure that the cost of the oil and gas using these processes was reasonable enough to make it commercially viable. In fact, if you've ever heard that the United States is now a net exporter of oil; a rather dramatic change from 50 years ago, it's because of the fracking technology used to extract that oil from locations that were not possible 50 years ago but this also comes with a significant environmental risk. For instance, conducting the fracking process so close to the water table as shown in the diagram increases the likelihood of contaminating what will end up being our drinking water with fracking chemicals or even the oil and gas itself. Another cause for concern is that we're breaking up shale rock that has been there for millions of years. In some regions where this is being done rather extensively there has been a major increase in seismic activity, meaning a lot more earthquakes. The horizontal drilling capability means that the drill site can start far from anyone and end up underneath a neighborhood or a school which of course brings with it plenty of legal issues about mining rights in addition to environmental concerns, but let's face it. We need the oil to produce the gasoline that we all use in driving our cars, and we need that natural gas that generates the electricity, heats our homes, and in many cases, cooks our food. Until we decide we're going to do things differently, these processes will continue to be around for a while. Let's summarize our discussion with a few main takeaways. For one, fossil fuels such as: coal, natural gas, and oil, are all derived from plant and animal matter that lived millions of years ago and are therefore considered non-renewable energy sources. We don't have the time to allow more coal, natural gas, or oil to form. Coal is accessed using strip mining and mountaintop removal techniques if the coal seam is close to the surface or underground mining operations if it's deep within the Earth. Oil and natural gas usually occur together. In the early days, one could drill down into a reservoir and just pump them out without a whole lot of difficulty. Nowadays though we have to go much deeper, and in far more remote locations greatly increasing the risks if something goes wrong. Today and especially in the US, the oil and gas are trapped within pores of rock known as shale and are accessed by breaking up the shale using fracking techniques. As we've shown, extracting fossil fuels entails risks both to people and the environment. As we go to more extreme regions to find fossil fuels or use techniques that we now know have unintended consequences, these risks become very real indeed. As we know, fossil fuels are burned to create heat. In our next lesson, we're going to show how much heat is in fossil fuels such as: coal, natural gas, and oil. We're also going to introduce some units that you may or may not be familiar with, but this way we can start to speak with a common language and that helps us to communicate our ideas with others. I'll see you next time.