Glossary: D to F
A-C | D-F | G-I | J-L | M-O | P-R | S-U | V-Z
D
Daylighting (natural lighting): Daylighting is the use of various design techniques to enhance the use of natural light in a building. Daylighting decreases reliance on electric lights and mechanical systems through the use of windows, skylights, light shelves, and other techniques that maximize sunlight while minimizing glare and excess heat. Green buildings often use daylighting.
Department of Environmental Protection (DEP): The DEP is the Massachusetts state agency overseeing the Commonwealth's environmental regulatory programs for air quality, wetland, and offshore protection, drinking water, solid waste (including hazardous waste), and land use controls. The DEP plays a significant role in developing and enforcing air quality regulations that affect fossil fuel generation as well as the lower emissions from biomass generation.
Department of Telecommunications and Energy (DTE): The DTE is an agency responsible for the regulation of telecommunications and energy in Massachusetts. In terms of clean energy, it plays a significant role in the development of rates, standards, and energy facility siting processes that impact the approval process for clean energy installations. The Department seeks to ensure that utility consumers are provided with the most reliable service at the lowest possible cost as determined by its orders and to ensure that residential ratepayers' rights are protected under regulations.
Direct current (DC): A direct current means that electrical current flows in a single direction through a conductor. DC must be converted to alternating current (AC) to be used for a typical 120-volt or 220-volt household appliance. DC is used directly in industrial applications and appliances that use battery power.
Division of Energy Resources (DOER): The DOER is a state agency that implements energy policies that ensure an adequate supply of reliable, affordable, and clean energy for the businesses and residents of Massachusetts. It seeks to improve and streamline energy regulation, promote greater efficiency in all energy applications, reduce energy costs, and mobilize energy education.
E
Electric utility: An entity that owns and operates transmission and/or distribution facilities and delivers electric energy to customers. It may be an investor-owned, municipal, state, or federal electric utility, or a rural electric cooperative. Find your local Massachusetts utility.
Electrical circuit: The path followed by electrons from a power source such as a photovoltaic (solar) panel, through an electrical system to create light, motion, battery power, and other power. The circuit is completed when the electrons return to the power source, creating a continuous flow of electricity.
Electrical current: The flow of electrons through an electrical wire, or transmission or distribution line. Current is measured in amperes.
Electrical energy: Electrical energy is the flow of electrons along a circuit. The movement of electrons creates an electric current which can be connected to an end use like lighting or appliances. Electrical energy can also be transformed into mechanical energy (using an elevator) or thermal energy (by using a space heater). Conversely, mechanical, thermal, and other forms of energy can be converted to create electricity, as in wind turbines and biomass facilities respectively. Electrical energy is usually measured in kilowatt-hours (kWh) or megawatt-hours (MW).
Electrical grid (electric grid): The grid can most easily be understood as a web of connections between power plants and the consumer of electricity. This web transfers electricity from power plants through transmission substations, high voltage transmission lines, distribution substations, and distribution lines to the consumer.
Electricity: See electrical energy.
Electricity supplier: Suppliers purchase electricity from generators and sell it to end-users (consumers). Suppliers are separate from distribution and transmission companies and consumers can choose their supplier based on price and fuel sources.
Electron: A negatively charged particle that is part of an atom. When electrons move among atoms to balance charges, an electrical current is created.
Emissions: Emissions are gases and particles released into the air as byproducts of a natural or man-made process. One of these processes is the burning of fuels to create electricity and other forms of energy. The emissions from burning fossil fuels contribute significantly to global warming and poor air quality. A small set of emissions are responsible for the majority of human impacts on global climate change and health. These gases and particulates come from a variety of sources and can be categorized as greenhouse gas emissions (which affect climate change) and air quality emissions (which affect health as well as the environment). One of the primary benefits of clean energy is that it typically produces no emissions, significantly reducing climate change and health impacts.
Energy: The ability to do work or the ability to move an object. Energy occurs in two primary states, potential and kinetic. This energy can occur in a number of forms including electrical, thermal (heat), chemical, radiant, and mechanical energy.
Energy efficiency: Energy efficiency refers to products or systems designed to use less energy for the same or higher performance than regular products or systems. Energy-efficient buildings are designed to use less energy than traditional buildings; see green buildings for details. Saving energy through efficiency also saves money on utility bills and protects the environment by reducing fossil fuel consumption and emissions. Combining energy efficiency with renewable energy is even better for the environment.
Ethanol: A biofuel derived from grain and corn that can be used instead of or as an additive to gasoline. Ethanol is primarily used in transportation applications.
F
Fossil fuels: Fossil fuels (oil, coal, and natural gas) come from the long-term decomposition of plant and animal matter from millions of years ago. These fossil fuels are the main sources of energy used by Americans today to generate electricity, heat, and fuel for transportation. Because fossil fuels cannot be replenished on a human time scale once they are extracted and burned, they are a non-renewable resource. The byproducts of fossil fuel combustion, including carbon dioxide (CO2) and methane, are emissions that increase the “greenhouse” effect that causes global climate change. These emissions also cause many direct air pollution problems like poor air quality and acid rain. Read more about fossil fuels’ environmental impacts.
Fuel cells: A fuel cell is an electrochemical device used to create electricity. Much like a battery, it converts chemical energy to electrical energy. But unlike a typical battery, which holds a limited fuel supply in a sealed container, a fuel cell uses an ongoing supply of fuel to create a continuous flow of electricity. Fuels like natural gas and methane gas are used to produce hydrogen and oxygen. The hydrogen and oxygen are then fed to two terminals in the fuel cell to cause a chemical reaction that produces electricity with heat and water as byproducts. Learn more about fuel cells.