In the last lesson, we talked about energy transitions throughout our history on planet Earth. In this lesson, we're going to look at the complex network, of energy sources and production, around the world today, to help guide us in understanding tomorrow's transitions. We'll also sneak a peek, at how different organizations see those transitions, unfolding down the road. Even at the very highest level, energy production, and consumption, is hugely complex. This chart, is called a sankey, diagram, it shows how humanity uses energy in the modern world, as of 2018. On the left, we see our primary energy sources, those things, that we can drill for, mine, or capture, to create energy, that we can use. The width of the ribbons, is proportional, to how much energy, they supply, from the diagram, it's clear, that fossil fuels oil, coal, and natural gas, produce most, more than 80%, of our energy today. On the right, we see, the end uses for energy, which have been split up into three main categories, transportation, industry, and buildings. Of course, oil fuels most transportation today, in the form of gasoline, diesel, maritime, and aviation fuels, different industrial processes use different fuels. Lots of coal, is used to make iron, and steel, as well as materials, like cement, oil and gas, are feedstocks for making plastics, and other petrochemicals. And electricity fuels, many manufacturing processes, buildings, our homes, offices, factories, and public spaces, are big energy consumers, as well. Not only, do we have to heat them in the winter, and cool them in the summer, we have to heat water, power appliances, and cook, whether we are fortunate enough to have a stove, or not. Well, electricity, is important for most of these tasks, we use a lot of natural gas, for space heating, and water heating, and biomass, wood, or wood pellets and wealthy nations. But almost anything burnable, including cow dung, in poorer countries, for cooking, and heating. But, we need to dig, a little deeper, to fully understand these energy flows, as complicated as they appear, to be. We already saw, that primary energy supply, refers to the total amount of energy, we need to power all the things we do. Some of our primary energy, is used to make electricity, which is not primary energy itself, but an energy vector, that allows us to apply, the primary energy, to a final use. But some of that primary energy gets wasted, lost, in converting energy from, burning coal, to electricity. If we have a pile of coal, containing 100 units of energy, we can produce only 30, to 35 energy units of electricity, that is actually useful. Same thing with making another energy currency, hydrogen, from primary energy sources like natural gas, or solar, and wind. The useful energy carried by the hydrogen, is less, than the energy we spent making it. And when we transmit that electricity through wires across the grid, we lose some of it, wasted, heating up those wires. And some of the primary energy we use creating hydrogen, is lost, when we use the hydrogen, as a fuel, whether to generate electricity, or, power a vehicle. So, we can actually consume, less primary energy, that is, burn less fuel, if we convert it, to a usable form, and transport it, more efficiently, reducing, our losses. So, let's go back, to the same diagram to apply those thoughts, you can see, that a lot of the primary energy, coal, gas, biomass, geothermal, solar, hydro, nuclear, and wind. Goes into making electricity, but less than 50% ,of that primary energy going in, on the left, comes out on the right, as usable, electrical energy. We lose the rest at the transformation stage, generating electricity, is not the only place we lose some of the primary energy that enters our energy flow system. Well, it's not shown on this diagram, we lose energy further downstream, as well. For example, energy is used to refine crude oil, into final products, like gasoline, and more energy is lost in the engines of cars, and trucks. As they convert energy from, gasoline, or electricity, to the energy that eventually, turns the wheels again. Again, more efficient conversion of primary energy, to usable energy, can increase the energy available to us, without growing the primary energy supply. We're going to talk more about energy efficiency, later in the course, if we zoom in, from the global scale to individual countries. We see, that every nation, consumes energy according to the resources it has available. Remember, that we're talking about energy, for everything, transportation, industries, and buildings, not just electrical generation. Let's compare energy consumption, for the time period 1969, to 2018, for a few countries, starting with Canada. Note, the chart starts at 1969 on the left, and goes to 2018, on the right, total energy consumption is on the vertical axis. And thickness, of the colored bands, is proportional, to the amount, of energy consumed, from a particular source. Canada, is fortunate to have many available energy sources, oil powers, transportation and industry, and natural gas, is important for heating, and power generation. Because of its geography, Canada has abundant hydroelectric resources, and nuclear, has been a mainstay, of power generation, in parts of the country since the 1970s. Coal, is burned for power, in a few provinces, while wind, and solar command a small part of the electrical generation market. China, consumes vastly more energy today, than in 1969, and most of the growth has been fueled by coal, and to a lesser extent by oil. Hydro, and natural gas have grown over the past decade, while nuclear, and wind, have a small, but growing share, of power generation. On the other side of the world, Iceland has experienced explosive growth, in energy consumption. But Iceland has a small population, high mountains, lots of rain and snow, and sits on the mid Atlantic rich, a very hot spot, on the earth's crust. So, Icelanders can meet their energy demand largely with hydropower, and more recently with geothermal energy, only a small part of their energy demand, is met by oil, for transportation. Otherwise, Iceland has a very low emissions, energy mix, in Germany, you may have heard about the energy vendor, the ongoing transition to a low emissions energy supply. Germany, has a mature economy, and overall energy consumption has not grown greatly since 1969. But, we see, in 2018, that energy consumption is still dominated by oil, coal, and gas. And while coal usage has definitely been reduced, gasses, market share, is much larger. Nuclear power was growing in importance until about 10 years ago, when the Fukushima accident in Japan, led Germany to move away, from nuclear power. Wind, biofuels, and solar, are growing in importance, but still provide only a fraction of total German energy supply, a fraction that is larger today than it was in 2018. [MUSIC] We can't leave, the introduction to energy sources, without addressing, renewable, versus non renewable energy, renewable resources, are naturally replenished on a human timescale. The sun shines every day, although sometimes about the clouds, the wind blows a lot of the time, depending on where you live. Rain falls, and flows into rivers to recharge hydropower, the tides, flow in and out twice every day. Geothermal energy, is renewed by endless heat resources deep in the earth, we generally associate renewables with low greenhouse gas, or GHG, emissions. Atleast, after the turbines, or solar panels have been built, some renewables are a little more problematic. We can harvest, and burn wood, call it a biofuel, and grow new trees, to replace those we've cut down, but that's a more complicated story, which we'll talk about later. Non renewable energy resources, are extracted from a finite supply, and combusted or reacted to obtain energy. Once we've used them, they're gone, coal, oil, and natural gas are the classic, non renewable energy resources, and they all generate, GHG emissions, while being burnt to produce energy. Nuclear power, relies on nonrenewable uranium and other radioactive elements, but they do not generate GHG emissions when producing energy. Let's keep these distinctions, between renewable, and non renewable energy sources in mind. And in particular, remember, that some renewables emit greenhouse gasses, will some, non renewables. [MUSIC] Looking ahead, the 21st century energy transition is all about, how the energy sources we use today, will change in the future, to achieve humanity social, economic, and environmental goals. Many organizations have their own views, of how and when the changes will happen. Some have very definite goals, and predictions, but most visualize different scenarios for energy transition, reflecting different pathways we might take, to achieve our goals. I recommend, you look at some of these reports, and you'll see what huge differences there are, all based on assumptions, and judgments, as to what people will do, in the future. We'll come back, to the different scenarios, after the next section of the course, where we'll look at the major energy sources, renewable, and non renewable, available to us today, and in the future. [MUSIC]
