Energy Glossary

Interested in clean energy advocacy but feeling lost in a maze of mysterious, arcane jargon? We’re here to help! Energy systems are labyrinths of complicated, heavily regulated technologies that are designed to support our modern comforts and conveniences. It may be as easy as a flip of a switch, but the network of energy policy, markets, and infrastructure is shockingly complicated.   

Here’s a glossary of terms to help you get started. We will update and expand this list periodically, and we welcome any suggestions you may have for new terms to add! If you would like to stay up to date, please sign up to receive occasional email newsletters on the Coastal Conservation League’s work to advance an equitable clean energy transition in South Carolina.  

Usage tip: This glossary is organized in alphabetical order. To look for specific terms, you can use Ctrl+F on Windows or Command+F on MacOS. 

• Act 62 (“Energy Freedom Act”) – a South Carolina law passed in 2019 that included regulations for integrated resource plans (IRPs). Some of these regulations included best practices to meet energy demand through renewable sources and public notices and hearings for transparency. 

• Act 236 – a South Carolina law passed in 2014 that incentivized distributed solar energy programs, which generate solar energy at the location where the energy is used, such as homes and businesses. These incentives included an expansion of net metering (up to a certain capacity) and tax credits and rebates for solar installations. 

• Battery energy storage systems (BESS) – Large-scale installations that store energy for later use. Electric utilities use these systems to meet provide energy when there is high demand, such as during peak hours. BESS help stabilize the electric grid, which can help to integrate more renewable energy onto the grid by ensuring that sufficient dispatchable capacity is available as needed. 

• Base Rates – Base charge that customers pay to have electricity delivered. These rates cover the costs of   utilities’ core operating expenses and capital expenditures, with allows investor-owned utilities to gain a return on their investment. The final rates typically include additional adjustment mechanisms and/or rate riders. 

• Capacity – the maximum amount of electricity that a power plant or other generating asset can produce at any moment in time, measured in Watts. May refer to operating capacity or nameplate capacity. 

• Capacity Factor – a measure of how much a power plant or other generating asset runs relative to its maximum potential throughout the year. Expressed as a percentage, capacity factor is calculated as Annual Net Generation / (Operating Capacity * 8760). 

• Clean Air Act (CAA) – landmark federal legislation that established the national framework for regulating harmful air emissions from power plants and other sources. 

• Combined-Cycle Gas Turbine (CCGT) – a gas-fired power plant design that incorporates combustion turbines and steam turbines in a configuration that utilizes Rankine Cycle heat recovery. CCGTs have efficiency gains and tend to have higher capacity factors compared to combustion turbines or gas-fired steam turbines alone. 

• Combustion Turbine (CT) – a type of gas-fired power plant similar to a jet engine, which can be rapidly ramped up to meet demand for electricity during times of peak demand. These plants are typically utilized as a type of peaker and have largely replaced less cost-effective internal-combustion peakers that burned fuel oils, such as diesel.  

• Community Solar – programs that allow customers to own or lease a portion of an off-site solar installation, which is typically larger in scale than residential rooftop solar installations. These programs may enable customers to save money on their bills, and they are particularly beneficial for renters and customers who may not have suitable rooftops for solar. 

• Conductor – a material through which electricity flows, particularly the lines used for transmission and distribution. 

• Cost of Saved Energy (COSE) – the amount of money it takes to achieve energy savings in an energy efficiency program, typically expressed in $/kWh. 

• Demand Response (DR) – optional utility programs that compensate customers for curtailing their energy usage during times of peak demand. 

• Demand-Side Management (DSM) – utility programs that manage demand to reduce costs, including demand response and energy efficiency programs. 

• Dispatch – turning on a power plant to start producing power. 

• Distributed Energy Resources (DER) – generation and energy storage resources that are smaller in scale than traditional power plants and are spread across an electric distribution system, including customer-sited resources like rooftop solar and battery storage, community solar, and virtual power plants (VPPs). 

• Distribution – the delivery of electric power to end-users via power lines connected to substations. Not to be confused with transmission.  

• Energy Burden—the percentage of a household’s income that is spent on home energy bills. South Carolina has some of the highest average energy burdens in the country. 

• Energy Conservation – choosing to use less energy by forgoing certain results. For example, setting your thermostat to 78 in the summer and 68 in the winter, as recommended by the Department of Energy, could be considered conservation if you would prefer to set your thermostat cooler in the summer and warmer in the winter. 

• Energy Efficiency (EE) – being able to get the same result with less energy. This includes behavioral energy efficiency, such as turning off lights when leaving a room or using a programmable thermostat to adjust setpoints to save energy when nobody is home. Energy efficiency programs are offered by many utilities and other entities. These programs can cost-effectively reduce the need for additional fuel and generating capacity to meet demand, thereby reducing system costs and emissions. 

• Energy Freedom Act – see Act 62. 

• Federal Energy Regulatory Commission (FERC) – the federal body responsible for regulating interstate transmission of electricity and pipeline gas, with authority over resource planning and ratemaking. 

• Generation – the production of electricity, commonly measured in megawatt-hours (MWh). 

• Gigawatt – a billion Watts. 

• Gigawatt-hour – a billion Watt-hours. 

• Independent Power Producer (IPP) – a company or other entity that owns generating capacity but is not a traditional electric utility. 

• Integrated Resource Plan (IRP) – a long-range utility plan that includes a load forecast and energy resource portfolios that are economically optimized to meet future energy needs in a 15-year period under various scenarios. In South Carolina, triennial IRPs and annual updates are subject to review by the Public Service Commission. The Coastal Conservation League intervenes in these proceedings. 

• Kilowatt (kW) – a thousand Watts. 

• Load – the amount of power drawn at a given time, either by a single user, a customer class, a utility system, or multiple utility systems. 

• Load Factor – a measure of how much power is used by an electrical load, relative to its maximum potential usage throughout the year. Measured as a percentage, it is calculated as Consumption / (Load * 8760). 

• Megawatt (MW) – a million Watts. 

• Megawatt-hour (MWh) – a million Watt-hours. 

• Nameplate Capacity – the rated capacity of a power plant or other generating asset, according to its manufacturer. 

• Net Generation – the generation produced by a power plant, excluding the amount of power consumed on-site. Commonly measured in megawatt-hours (MWh). 

• Operating Capacity – the usable capacity of a power plant or other generating asset, as influenced by the climate and operating conditions of the site where it is installed. Seasonal operating capacities may differ and may be reported separately. 

• Peak Load – the highest instantaneous amount of demand on an electrical system within a period of time. Typically measured in GW. 

• Peaker – a power plant that typically only runs during times of high demand on the electrical system. Peaker plants have higher marginal operating costs but are able to ramp up to full capacity relatively quickly. Currently, most peakers are gas-fired combustion turbines. 

• Photovoltaic (PV) – the most common form of solar energy, which utilizes panels comprised of silicon wafers and other components to convert sunlight into electricity. 

• Power Purchase Agreement (PPA) – a contract to purchase power, often entered into by a utility and an independent power producer. 

• Public Service Commission (PSC) – the primary regulator of utilities and other monopolies in South Carolina. 

• Ramp Rate – the amount of time it takes for a power plant can reach full generating capacity from a cold start. 

• Rankine Cycle – the process of utilizing waste heat from a generating unit to produce additional power via a steam turbine. The Rankine Cycle is utilized on combined-cycle power plants. 

• Rate Base – the utility assets that are included in the calculation of base rates. 

• Rate Case – a regulatory proceeding in which a commission reviews potential changes to a utility’s service rates. 

• Rate Riders – the portions of utility rates that are outside of base rates. The largest rate rider for electric utilities is typically a fuel-cost recovery mechanism. Other common rate riders include demand-side management program cost-recovery riders and riders tied to distributed solar energy programs. Some riders are optional for customers. 

• Renewable Energy – energy resources that are naturally replenished at a faster rate than they are used. Examples include hydroelectric, solar, and wind energy. 

• Reserve Margin – the amount of capacity above forecasted peak loads that a utility plans to have available as a precaution against potential shortfalls. 

• Resource Optimization Model – a data model that is used to develop portfolios of generation and transmission assets that minimizes cost while meeting regulatory requirements, including adequate reliability. 

• Steam Turbine (ST) – a type of generating unit that utilizes pressurized steam in a boiler to turn a turbine and generate electricity. 

• Substation – a facility that connects points of an electrical transmission system to each other or to a distribution system. Substations have transformers and switching equipment. 

• Transformer – equipment that changes the voltage of electricity. 

• Transmission – the conveyance of electric power over long distances via power lines connecting power plants to substations. Not to be confused with distribution. 

• Watt – the primary unit of measurement used to quantify the rate of energy transfer. 

• Watt-hour – the average Watts transferred from point-to-point over an hour. 

• Weatherization – insulation and air sealing in a building to reduce the amount of energy needed to maintain comfortable indoor temperatures and humidity levels.