Energy in the Western US
Everything we do depends upon energy—without it there would be no civilization, no sunlight, no food, and no life. Energy moves people and goods, produces electricity, heats our homes and businesses, and is used in manufacturing and other industrial processes. But what is energy? Energy is the power derived from the utilization of physical or chemical resources. In this chapter, we are especially interested in the energy used to provide light and heat, or to power machines.
For most of human history, the way we captured and used energy changed little. With very few exceptions, materials were moved by human or animal power, and heat was produced largely through the burning of wood. Nearly all the energy to power human society was, in other words, biomass*. But the transition from brute force and wood burning to the various industrial sources of energy— and the accompanying adoption of energy-intensive lifestyles—has occurred remarkably quickly, in the course of just the last several generations. This has caused changes in virtually every aspect of human life, from economics to war to architecture. Much of the rural US was without access to electricity until the 1930s, and cars have been around only slightly longer. Our energy system (how we get energy and what we use it for) has changed and is changing remarkably quickly, though some aspects of the energy system are also remarkably resistant to change.
* Exceptions include the use of sails on boats by a very small percentage of the world’s population to move people and goods, and the Chinese use of natural gas to boil brine in the production of salt beginning roughly 2000 years ago.
Electricity is a good example of an energy carrier: a source of energy that has been subject to human-induced energy transfers or transformations.
Wind power, on the other hand, is a primary energy source: a source of energy found in nature that has not been subject to any human manipulation.
The use of wind to generate electricity, for example, grew very quickly in the late 2000s and early 2010s. In 2002, wind produced less than 11 million megawatt hours (MWh) of electricity in the US. In 2011, wind produced more than 120 million MWh—more than 1000% growth in ten years! That aspect of change stands in contrast to our long-lasting reliance on fossil fuels, coal, oil, and natural gas. Our reliance on fossil fuels is driven by a number of factors: the low upfront cost, very high energy densities, and the cost and durability of the infrastructure built to use fossil fuels.
Energy production and use not only changes across time, but also with geography, as we will see by looking at energy production and use across the different regions of the US.
What do different units of energy mean?
Heat is energy, and heat is at the root of all the ways that we move materials or generate light, so measurements of heat can be thought of as the most basic way to measure energy. The British Thermal Unit (abbreviated Btu or BTU) is the most commonly used unit for heat energy and is approximately the amount of heat required to raise one pound of water by one degree Fahrenheit. A Btu is also about the amount of energy released by burning a single wooden match. One Btu is also equal to 1055 joules. A joule is the energy expended (or work done) to apply a force of one newton over a distance of one meter. A typical apple weighs about a newton, so lifting an apple one meter takes about a joule of energy. That means that one Btu—the energy contained in a wooden match—would be all the energy required to lift an apple 1000 meters, or a kilometer.
The principle of Conservation of Energy tells us that energy is neither created nor destroyed, but can be altered from one form to another.
This comparison of the energy of heat to the energy of motion (kinetic energy) might be a little confusing, but energy is transformed from one type to another all the time in our energy system. This is perhaps most obvious with electricity, where electrical energy is transformed into light, heat, or motion at the flip of a switch. Those processes can also be reversed—light, heat, and motion can all be transformed into electricity. The machines that make those transitions in either direction are always imperfect, so energy always degrades into heat when it is transformed from one form to another. A kilowatt-hour (kWh) is the amount of energy required to light ten 100-watt light bulbs for one hour. Figure 7.1 compares different ways to make and use one kWh.
Figure 7.2. US energy production sources and use sectors for 2011. Petroleum provides more energy than any other source, and most of it is used for transportation. More energy is used to generate electricity than for any other use, and electricity is generated by all five energy sources. Nuclear is unique among sources in that all of the energy it generates goes to a single sector: electric generation.
How do we look at energy in the Earth system?
The concepts used to understand energy in the Earth system are fundamental to all disciplines of science; energy is an interdisciplinary topic. One cannot study physics or understand biomes, photosynthesis, fire, evolution, seismology, chemical reactions, or genetics without considering energy. In the US, every successive generation has enjoyed the luxury of more advanced technology (e.g., the ability to travel more frequently, more quickly, and over greater distances), and we require more and more energy to maintain these new lifestyles and to power new technologies.
Figure 7.2 shows the sources and uses of energy in the US, by sector. The Energy Information Administration (EIA) categorizes energy as coming from one of five sources (petroleum, natural gas, coal, renewable energy, and nuclear electric power) and being used in one of four energy sectors (transportation, industrial, residential & commercial, and electric power). All of the energy that powers our society comes from one of these five sources and is used in one of these four sectors.
The more we come to understand the Earth system, the more we realize that there is a finite amount of consumable energy, and that harvesting certain resources for use in energy consumption may have wide ranging and permanent effects on the planet’s life. Understanding energy within the Earth system is the first step to making informed decisions about energy transitions.
Becoming “Energy Literate”
Energy Literacy: Energy Principles and Fundamental Concepts for Energy Education is a publication of the US Department of Energy. It can be accessed for free online; see Resources for more information.
Energy is neither lost nor gained within the universe, but rather is constantly flowing through the Earth system. In order to fully understand energy in our daily lives—and make informed decisions—we need to understand energy in the context of that system. Becoming energy literate gives us the tools to apply this understanding to solving problems and answering questions. The Seven Principles of Energy, as detailed in Energy Literacy: Energy Principles and Fundamental Concepts for Energy Education are:
Each principle is defined by a set of fundamental concepts that can help clarify ties to curriculum. Keeping these energy principles in mind when we teach others about energy can help us contextualize and make relevant our own energy consumption and its effect on the Earth system.