Nonrenewable Energy Resources| AP Environmental science| Khan Academy
Today, let's talk about energy resources. You've probably already done something today that used energy resources, even beginning from the moment you woke up. For me, the beginning of my day always starts with making tea. I use energy in every step of this process. My car uses oil when I drive to the grocery store to get the tea. My stove uses natural gas when I boil the water, and my water heater uses coal-sourced electricity when I wash my mug in hot water.
Afterwards, we use energy constantly in our daily lives. Since the first law of thermodynamics states that energy cannot be created nor destroyed, where does it all come from and will we have enough? When we talk about energy resources, we could split it up into two groups: renewable energy and non-renewable energy. I can always remember what renewable resources are because the prefix "re" means again, and the root "new" refers to the origin of the energy source. So, renewable energy sources are the sources that we can use again and again and are quickly restored by natural processes.
Renewable fuel sources include sunlight, wind, moving water, biomass from fast-growing plants, and geothermal heat from the earth. The lifespan of renewable resources looks like a circle; we can use them, and then we can use them again without worrying about them running out. Non-renewable energy sources, on the other hand, are sources that exist in a fixed amount and cannot be easily replaced. These energy sources must be extracted from the earth, and they include things like nuclear fuel and fossil fuels, which are things like coal, oil, and natural gas.
Fossil fuels formed in the geologic past from the remains of ancient organisms. Plants and animals that died millions of years ago became buried in the soil, partially decomposed, and were exposed to a lot of heat and pressure. This heat and pressure chemically rearranged the energy contained within their bodies into the fossil fuels we use today. Because they take so long to form, we have a finite amount of non-renewable resources in the earth right now.
The lifespan for fossil fuels is a broken loop—a one-way ticket. First, the fossil fuel is found, then it has to be extracted. Extracting fossil fuels can involve destructive mining processes that can pollute surrounding habitats. It then has to be transported to wherever it will be used, and using fossil fuels means burning them, which releases greenhouse gases and other pollutants into the atmosphere. Also, it can take energy to refine and process some types of fossil fuels so that they're more helpful to us, like turning crude oil into petroleum, gas, diesel, and jet fuel.
Burning the fossil fuels transforms that energy into a less organized form of energy, like heat and ash. Not all fossil fuels are the same, and this is because different kinds of organic material were heated and compressed in different ways, creating different kinds of fossil fuels. One of these kinds of fossil fuels is petroleum. The word petroleum comes from the Latin word for rock, "petra," and the Latin word for oil, "oleum." This makes sense because it's an oily substance that's found in reservoirs trapped in rock.
Humans have been using oil for a very long time. Early civilizations found it bubbling up from the ground at natural wells. The oil they saw coming straight out of the earth is called crude oil or crude petroleum, which means that it is unrefined and unprocessed. Crude oil was probably one of the ingredients in Greek fire, which was a flame-throwing weapon that the Byzantines would fling at their enemies. Today, we refine crude oil into many products, like gasoline and diesel for vehicles, kerosene for heating, and asphalt for road construction. It's also used to make plastics and synthetic fabrics.
Another type of fossil fuel is coal, which we mostly burn to make electricity, but it can also be used for heating and cooking. It's a solid, shiny black flammable rock that is mostly formed from the carbon remains of fossilized plants, like moss. Over thousands of years, plant material transforms into a carbon-rich compound called peat, and then, with some pressure, it becomes soft coal, which is called lignite. With more pressure, it becomes bituminous coal, and then finally, it becomes a hard coal called anthracite.
The longer the plant remains are put under pressure, the more energy dense it becomes. So if you burned anthracite, you would get a lot more energy than if you burned peat. Burning coal releases carbon dioxide, sulfur dioxide, nitrogen oxides, and other gases into the air, so coal is one of the dirtiest fossil fuels. The cleanest-burning fossil fuel is natural gas, meaning that it emits the least amount of carbon dioxide or other air pollutants. This is not the same type of gas as we put into our vehicles; that type comes from petroleum.
Instead, natural gas is mostly used for generating electricity, heating homes, and cooking food. Your oven, furnace, water heater, dryer, or grill all might run on natural gas. Natural gas is a naturally occurring mixture of gases, and it's mostly made up of methane, ethane, propane, and butane. The gas is colorless and odorless, so natural gas companies often add a rotten egg smell to the fuel to make leaks easier to detect. But even though we can't see or smell natural gas, humans have been detecting it and using it for centuries.
There is evidence that more than 2,000 years ago, people in China created bamboo pipelines to transport the gas so that they could use it to boil salt water and separate out the salt. Today, we still use pipelines to transport gas across land, although they're no longer made out of bamboo. Another kind of non-renewable resource is nuclear fuel. Nuclear power plants don't burn fossil fuels; instead, they split uranium through something called nuclear fission. Just one kilogram of uranium can produce 24 million kilowatt-hours of energy. Compare that with one kilogram of coal, which can produce eight kilowatt-hours of energy.
In other words, nuclear fission produces a lot of energy. It also produces a lot of heat, which we mostly use to make electricity. Also, nuclear energy is known as clean energy because the only greenhouse gas emission is water vapor, which tends to cycle out of the atmosphere faster than other greenhouse gases. But the downside is the spent fuel is a dangerous radioactive waste, and recycling the nuclear waste is dangerous and expensive.
Petroleum, coal, natural gas, and nuclear fuel make up 85 percent of the world's energy consumption. But as our populations and our energy needs grow, it's becoming more important to integrate renewable resources—the sources that could be restored by natural processes—into our energy mix. I'm going to go make some tea now, but before I do, here's something to think about: What's something that you do in your day that uses energy? Does that energy come from fossil fuels, and if so, which one? Understanding how you get your energy is part of understanding what powers your community, your country, and the world.