Alternative and Renewable Energy - Advanced Materials ...

Spiral 2: 3/28/2011Department of Defense Energy HandbookAlternative and Renewable Energy Options for DoD Facilities and Bases6 ENERGY SUPPLY6.1 Introduction to Energy, Fuel, and PowerBasically defined, energy is a system’s ability to perform work, and power is the rate at which energy istransferred to perform work. There are many forms of energy but all forms can be placed into one oftwo categories: kinetic and potential. Kinetic energy is simply the energy of motion. Potential energy isthe energy stored by an object or system due to its position or state. Forms ofkinetic energy include radiant, sound, motion, and thermal energy. Forms ofpotential energy include electrical, chemical, gravitational, nuclear, and storedmechanical energy. A fuel is a substance that has stored energy which can bereleased deliberately to provide useful work or heat.There are many sources of energy which are used to perform work on a systemof any scale. For instance, on a molecular scale thermal energy can be used toform or destroy bonds between atoms and molecules. On a macroscopic scale,chemical energy stored in an energetic material, for example, can be used topropel a rocket away from the Earth’s gravitational pull.Energy behaves according to the First Law of Thermodynamics, also known asthe law of conservation of energy, which can be formalized as:Although energy assumes many forms, the total quantity of energy is constant,and when energy disappears in one form it appears simultaneously in otherforms. 37From this law it is clear that energy cannot be created, but rather converted from one form to another.Thus energy must be harvested from various sources, and then it can be used to power the function ofartificial devices and processes.6.1.1 Nonrenewable and Renewable EnergyEnergy sources can be categorized in a variety of ways. Perhaps the most meaningful approach is toseparate them into nonrenewable and renewable categories. Nonrenewable energy sources cannot beregenerated or replaced within a timescale that is sufficient to sustain their consumption. Thus, theseenergy sources will eventually become exhausted. Conversely, renewable energy sources can bereplenished by natural processes at a rate that exceeds their consumption.6.1.2 Traditional and Alternative EnergyKinetic Energy (Energy of Motion)• Radiant• Sound• Motion• ThermalPotential Energy (Stored Energy)• Electrical• Chemical• Mechanical• Gravitational• NuclearEnergy sources can also be categorized as traditional or alternative. Traditional energy sources are thosewhich have been in use for a long period of time to supply a substantial amount of power; these includesome renewable energy sources, such as hydroelectric power, and of course nonrenewable sources,such as fossil fuels.Alternative energy is a largely misused term. In the context of energy, alternative is often used as asynonym for renewable, and in some texts these terms appear interchangeably. However, the wordalternative means unconventional or nontraditional. It is the case that many renewable energy sourcesare alternative, but not all renewable energy sources are alternative. For instance, hydroelectric poweris a renewable resource, but is not unconventional and therefore not alternative. An example of anonrenewable, alternative resource is synthetic fuels.49