| Central Administration
Science Education Resource Center
| Carleton College
These controlled vocabularies are under development at SERC. They vary widely in terms of refinement and the
degree to which they have been tested with users. None represents a finished product. Caveat emptor.
Energy Literacy Principles
- Energy is a physical quantity Energy is a physical quantity that follows precise natural laws.
- 1.1 Energy is a quantity Energy is a quantity that is transferred from system to system.
Energy is the ability of a system to do work. A system has done work if it has exerted a force on another system over some distance. When this happens energy is transferred from one system to another. At least some of the energy is also transformed from one type into another during this process. One can keep track of how much energy transfers into or out of a system. 199:2 199:3 end
- 1.2 Thermal energy The energy of a system or object that results in its temperature is called thermal energy.
When there is a net transfer of energy from one system to another, due to a difference in temperature, we call the energy transferred heat. Heat transfer happens in three ways: convection, conduction and radiation. Like all energy transfer, heat transfer involves forces exerted over a distance at some level as systems interact. 199:2 199:4 end
- 1.3 Energy is neither created nor destroyed Energy is neither created nor destroyed.
The change in the total amount of energy in a system is always equal to the difference between the amount of energy transferred in and the amount transferred out. The total amount of energy in the universe is finite and constant. 199:2 199:7 end
- 1.4 Energy quality degrades over time Energy available to do useful work decreases as it is transferred from system to system.
Although energy is neither created nor destroyed, its quality degrades over time. During all transfers of energy between two systems, some energy is lost to the surroundings. In a practical sense, this lost energy has been “used up,” even though it is still around somewhere. A more efficient system will lose less energy, up to a theoretical limit. 199:2 199:8 end
- 1.5 Forms of energy Energy comes in different forms and can be divided into categories.
Forms of energy include light energy, elastic energy, chemical energy and more. There are two categories that all energy falls into, kinetic and potential. Kinetic describes types of energy associated with motion and the word potential describes energy possessed by an object or system due to its position relative to another object or system and forces between the two. Some forms of energy are part kinetic and part potential energy. 199:2 199:9 end
- 1.6 Chemical and nuclear reactions Chemical and nuclear reactions involve transfer and transformation of energy.
The energy associated with nuclear reactions is much larger than that associated with chemical reactions for a given amount of mass. Nuclear reactions take place at the centers of stars, in nuclear bombs and in both fission and fusion-based nuclear reactors. Chemical reactions are pervasive in living and non-living Earth systems.
199:2 199:10 end
- 1.7 Units of energy Many different units are used to quantify energy.
As with other physical quantities, many different units are associated with energy. For example, joules, calories, ergs, kilowatt-hours and BTUs are all units of energy. Given a quantity of energy in one set of units, one can always convert it to another (E.g., 1 calorie = 4.186 joules). 199:2 199:11 end
- 1.8 Power Power is a measure of energy transfer rate.
It is useful to talk about the rate at which energy is transferred from one system to another (energy per time). This rate is called power. One joule of energy transferred in one second is called a Watt (I.e., 1 joule/second = 1 Watt). 199:2 199:12 end
- Physical processes on Earth are the result of energy flow Physical processes on Earth are the result of energy flow through the Earth system.
- 2.1 Changes in energy flow over time Earth is constantly changing as energy flows through the system.
Geologic, fossil and ice records provide evidence of significant changes throughout Earth's history. These changes are always associated with changes in the flow of energy through the Earth system. Both living and non-living processes have contributed to this change. 199:5 199:13 end
- 2.2 Sources of energy on Earth Sunlight, gravitational potential, decay of radioactive isotopes, and rotation of the Earth are the major sources of energy driving physical processes on Earth.
Sunlight is a source external to Earth while radioactive isotopes and gravitational potential, with the exception of tides, are internal. Radioactive isotopes and gravity work together to produce geothermal energy beneath Earth's surface. Earth's rotation influences global flow of air and water. 199:5 199:14 end
- 2.3 Earth's climate driven by the Sun Earth's weather and climate is mostly driven by energy from the Sun.
For example, unequal warming of Earth's surface and atmosphere by the Sun drives convection within the atmosphere, producing winds, and influencing ocean currents. 199:5 199:15 end
- 2.4 Water stores and transfers energy Water plays a major role in the storage and transfer of energy in the Earth system.
This is due to water's prevalence, high heat capacity and the fact that phase changes of water occur regularly on Earth. The Sun provides the energy that drives the water cycle on Earth. 199:5 199:16 end
- 2.5 Energy moves between reservoirs Movement of matter between reservoirs is driven by Earth's internal and external sources of energy.
These movements are often accompanied by a change in the physical and chemical properties of the matter. Carbon, for example, occurs in carbonate rocks such as limestone, in the atmosphere as carbon dioxide gas, in water as dissolved carbon dioxide, and in all organisms as complex molecules that control the chemistry of life. Energy drives the flow of carbon between these different reservoirs.
199:5 199:17 end
- 2.6 Greenhouse gases affect energy flow Greenhouse gases affect energy flow through the Earth system.
Greenhouse gases in the atmosphere, such as carbon dioxide and water vapor, are transparent to much of the incoming Sunlight but not to the infrared light from the warmed surface of Earth. These gases play a major role in determining average global surface temperatures. When Earth emits the same amount of energy as it absorbs its average temperature remains stable. 199:5 199:18 end
- 2.7 Effects of changes in Earth's energy system The effects of changes in Earth's energy system are often not immediately apparent.
Responses to changes in Earth's energy system, input versus output, are often only noticeable over the course of months, years or even decades. 199:5 199:19 end
- Biological processes depend on energy flow Biological processes depend on energy flow through the Earth system.
- 3.1 The Sun is major source of energy for organisms and ecosystems The Sun is the major source of energy for organisms and the ecosystems of which they are a part.
Producers such as plants, algae and cyanobacteria use the energy from sunlight to make organic matter from carbon dioxide and water. This establishes the beginning of energy flow through almost all food webs. 199:6 199:20 end
- 3.2 Food is a biofuel Food is a biofuel used by organisms to acquire energy for internal living processes.
Food is composed of molecules that serve as fuel and building material for all organisms as energy stored in the molecules is released and used. The breakdown of food molecules enables cells to store energy in new molecules that are used to carry out the many functions of the cell and thus the organism. 199:6 199:21 end
- 3.3 Continual input of energy is needed Energy available to do useful work decreases as it is transferred from organism to organism.
The chemical elements that make up the molecules of living things are passed through food chains and are combined and recombined in different ways. At each level in a food chain, some energy is stored in newly made chemical structures, but most is dissipated into the environment. Continual input of energy, mostly from sunlight, keeps the process going.
199:6 199:22 end
- 3.4 Energy flows through food webs Energy flows through food webs in one direction, from producers to consumers and decomposers.
An organism that eats lower on a food chain is more energy efficient than one eating higher on a food chain. Eating producers is the lowest, and thus most energy efficient, level at which an animal can eat. 199:6 199:23 end
- 3.5 Ecosystems are affected by availability of energy. Ecosystems are affected by changes in the availability of energy and matter.
The amount and kind of energy and matter available constrains the distribution and abundance of organisms in an ecosystem and the ability of the ecosystem to recycle materials. 199:6 199:24 end
- 3.6 Humans live within Earth's ecosystems. Humans live within Earth's ecosystems.
Increasingly, humans modify the energy balance of Earth's ecosystems. The changes happen, for example, as a result of changes in agricultural and food processing technology, consumer habits, and human population size. 199:6 199:25 end
- Various sources of energy are used to power human activities
- 4.1 Humans transfer and transform energy Humans transfer and transform energy from the environment into forms useful for human endeavors.
The primary sources of energy in the environment include renewable sources such as sunlight, wind, moving water, and geothermal energy. Primary sources also include fuels like coal, oil, natural gas, uranium and biomass. All primary source fuels except biomass are non-renewable. 199:26 199:29 end
- 4.2 Human use of energy is subject to limits and constraints Human use of energy is subject to limits and constraints.
Industry, transportation, urban development, agriculture, and most other human activities are closely tied to the amount and kind of energy available.The availability of energy resources is constrained by the distribution of natural resources, availability of affordable technologies and socio-economic policies and status. 199:26 199:30 end
- 4.3 Fossil and bio fuels contain energy captured from sunlight Fossil and bio fuels are organic matter that contain energy captured from sunlight.
The energy in fossil fuels such as oil, natural gas and coal comes from energy that producers such as plants, algae and cyanobacteria, captured from sunlight long ago. The energy in biofuels such as food, wood, and ethanol comes from energy that producers captured from sunlight very recently. Energy stored in these fuels is released during chemical reactions, such as combustion and respiration, which also release carbon dioxide into the atmosphere. 199:26 199:31 end
- 4.4 Humans transport energy Humans transport energy from place to place.
Fuels are often not used at their source but are transported, sometimes over long distances. Fuels are transported primarily by pipelines, trucks, ships, and trains. Electrical energy can be generated from a variety of energy resources and can be transformed into almost any other form of energy. Electric circuits are used to distribute energy to distant locations. Electricity is not a primary energy source, but a means of transmitting energy. 199:26 199:32 end
- 4.5 Electricity generation Electricity is usually generated in one of two ways.
When a magnet moves or magnetic field changes relative to a coil of wire, electrons are induced to flow in the wire. Most human generation of electricity happens in this way. Electrons can also be induced to flow through direct interaction with light particles; this is the basis upon which a solar cell operates. 199:26 199:33 end
- 4.6 Humans store energy Humans intentionally store energy for later use in a number of different ways.
Examples include batteries, water reservoirs, compressed air, hydrogen and thermal storage. Storage of energy involves many technological, environmental and social challenges. 199:26 199:34 end
- 4.7 Different sources of energy have different benefits and drawbacks Different sources of energy and the different ways energy can be transformed, transported and stored each have different benefits and drawbacks.
A given energy system, from source to sink, will have an inherent level of energy efficiency, monetary cost and environmental risk. Each system will also have national security, access and equity implications. 199:26 199:35 end
- Energy decisions are influenced by several factors
- 5.1 Energy decisions are made at many levels Decisions concerning the use of energy resources are made at many levels.
Humans make individual, community, national and international energy decisions. Each of these levels of decision making have some common and some unique aspects. In the developed world, decisions made beyond the individual level usually involve a formally established process. 199:27 199:36 end
- 5.2 Energy infrastructure has inertia Energy infrastructure has inertia.
The decisions that governments, corporations, and individuals made in the past have created today's energy infrastructure. The large amount of money, time, and technology invested in these systems make changing the infrastructure difficult, but not impossible. The decisions of one generation both provide and limit the range of possibilities open to the future generations. 199:27 199:37 end
- 5.3 Systems-based approach Energy decisions can be made using a systems-based approach.
As individuals and societies make energy decisions they can consider the costs and benefits of each decision. Some costs and benefits are more obvious than others. Identifying all costs and benefits requires a careful and informed systems-based approach to decision making. 199:27 199:38 end
- 5.4 Economic factors Energy decisions are influenced by economic factors.
Monetary costs of energy affect energy decision making at all levels. Energy exhibits characteristics of both a commodity and a differentiable product. Energy costs are often subject to market fluctuations and energy choices made by individuals and societies affect these fluctuations. Cost differences also arise as a result of differences in energy source and as a result of tax-based incentives and rebates. 199:27 199:39 end
- 5.5 Political factors Energy decisions are influenced by political factors.
Political factors play a role in energy decision making at all levels. These factors include, but are not limited to, governmental structure and power balances, actions taken by politicians, and partisan-based or self serving actions taken by individuals and groups. 199:27 199:40 end
- 5.6 Environmental factors Energy decisions are influenced by environmental factors.
Environmental costs of energy decisions affect energy decision making at all levels. All energy decisions have environmental consequences. These consequences can be positive or negative. 199:27 199:41 end
- 5.7 Social Factors Energy decisions are influenced by social factors.
Questions of ethics, morality and social norms affect energy decision making at all levels. Social factors often involve economic, political and environmental factors. 199:27 199:42 end
- Human use of energy
- 6.1 Two meanings 'conservation of energy' Conservation of energy has two very different meanings.
There is the physical law of conservation of energy, also known as the First Law of Thermodynamics. This law says that the total amount of energy in the Universe is constant. Conserving energy is also commonly used to mean the decreased use of societal energy resources. When speaking of people conserving energy this second meaning is always intended. 199:28 199:43 end
- 6.2 Conserving energy One way to manage energy resources is through conservation.
Conservation includes reducing wasteful energy use, using energy for a given purpose more efficiently, making strategic choices as to sources of energy and reducing energy use altogether. 199:28 199:44 end
- 6.3 Demand for energy is increasing Human demand for energy is increasing.
Population growth, industrialization and socio-economic development result in increased demand for energy. Societies have choices with regard to how they respond to this increase. Each of these choices has consequences. 199:28 199:45 end
- 6.4 Earth has finite energy resources Earth has finite energy resources.
Increasing human energy consumption places stress on the natural processes that renew some energy resources and it depletes those that cannot be renewed. 199:28 199:46 end
- 6.5 Social and technological innovation Social and technological innovation affects the amount of energy used by human society.
The amount of energy society uses per capita or in total can be decreased. Decreases will happen as a result of technological and social innovation and change. Decreased use of energy does not equate to decreased quality of life. In many cases it will be associated with increased quality of life in the form of increased economic and national security, reduced environmental risks and monetary savings. 199:28 199:47 end
- 6.6 Behavior and design Behavior and design affect the amount of energy used by human society.
There are actions individuals and society can take to conserve energy. These actions might come in the form of changes in behavior or in changes to the design of technology and infrastructure. Some of these actions have more impact than others. 199:28 199:48 end
- 6.7 Embedded energy Products and services carry with them embedded energy.
The energy needed for the entire lifecycle of a product or service is called the “embedded” or “embodied” energy. An accounting of the embedded energy in a product or service along with knowledge of the source(s) of the energy is essential when calculating the amount of energy used and in assessing impacts and consequences. 199:28 199:49 end
- 6.8 Calculating and monitoring energy use Amount of energy used can be calculated and monitored.
An individual, organization or government can monitor, measure and control energy use in many ways. Understanding utility costs, knowing where consumer goods and food come from, and understanding energy efficiency as it relates to home, work and transportation are essential to this process. 199:28 199:50 end
- Energy affects quality of life The quality of life of individuals and societies is affected by energy choices.
- 7.1 Economic security Economic security is impacted by energy choices.
Individuals and society continually make energy choices that have economic consequences. These consequences come in the form of monetary cost in general and in the form of price fluctuation and instability specifically. 199:1 199:51 end
- 7.2 National security National security is impacted by energy choices.
The security of a nation is dependent, in part, on the sources of that nation's energy supplies. For example, a nation that has diverse sources of energy that come mostly from within its borders is more secure than a nation largely dependent on foreign energy supplies. 199:1 199:52 end
- 7.3 Environmental quality Environmental quality is impacted by energy choices.
Energy choices made by humans have environmental consequences. The quality of life of humans and other organisms on Earth can be significantly affected by these consequences. 199:1 199:53 end
- 7.4 Fossil fuel supplies are limited Increasing demand for and limited supplies of fossil fuels affects quality of life.
Fossil fuels provide the vast majority of the world's energy. Fossil fuel supplies are limited. If society has not transitioned to sources of energy that are renewable before depleting Earth's fossil fuel supplies, it will find itself in a situation where energy demand far exceeds energy supply. This will have many social and economic consequences. 199:1 199:54 end
- 7.5 Access to energy affects quality of life Access to energy resources affects quality of life.
Access to energy resources, or lack thereof, affects human health, access to education, socio-economic status, gender equality, global partnerships and the environment. 199:1 199:55 end
- 7.6 Vulnerable populations Some populations are more vulnerable to impacts of energy choices than others.
Energy decisions have economic, social and environmental consequences. Poor, marginalized or underdeveloped populations can most benefit from positive consequences and are the most susceptible to negative consequences. 199:1 199:56 end