Welcome to our comprehensive energy storage glossary, where we dive deep into the key terms and concepts that shape the world of energy storage. In this guide, you’ll find definitions and explanations for everything from battery chemistry to energy management systems. So whether you’re a seasoned professional or just starting to explore the world of energy storage, this glossary has something for you.
- Lithium-ion (Li-ion) Batteries: A popular choice for energy storage systems, Li-ion batteries offer a high energy density, long cycle life, and fast charging capabilities. They come in various chemistries, including lithium iron phosphate (LiFePO4) and lithium nickel manganese cobalt oxide (NMC).
- Lead-Acid Batteries: An older technology, lead-acid batteries are less expensive but have a shorter life cycle and lower energy density than Li-ion batteries.
- Flow Batteries: A type of rechargeable battery that uses liquid electrolytes, flow batteries are known for their long cycle life and scalability.
Energy Storage Systems
- Battery Storage: Battery storage systems store energy generated by renewable sources, like solar or wind, for use during peak demand or when renewable generation is low. This helps balance the grid and reduce reliance on fossil fuels.
- Flywheel Energy Storage: A mechanical energy storage system that stores energy in a rotating mass, flywheel energy storage systems have a fast response time and high efficiency.
- Green Hydrogen: An emerging energy storage technology, green hydrogen is produced through the electrolysis of water using renewable energy. It can be stored and used as a fuel when needed.
Solar Power Integration
- Hybrid Solar Inverter: A device that combines the functions of a solar inverter and a battery inverter, hybrid solar inverters enable seamless integration of solar power and energy storage systems.
- DC Coupling: A method of connecting a solar array and energy storage system that uses a single inverter, improving overall system efficiency.
Electric Vehicle Charging
- EV Charging Infrastructure: The network of charging stations and equipment required to support electric vehicles, including Level 1, Level 2, and DC fast chargers.
- Vehicle-to-Grid (V2G): A technology that allows electric vehicles to discharge energy back into the grid, helping to balance grid demand and potentially earning revenue for EV owners.
Energy Management Systems
- Energy Management System (EMS): A system that monitors and optimizes energy consumption across a building or facility, including demand response, load control, and energy efficiency measures. An EMS can integrate with renewable energy generation and energy storage systems to optimize overall energy use and reduce costs.
- Home Energy Management System (HEMS): A type of EMS designed specifically for residential use, HEMS enable homeowners to monitor and manage their energy consumption, solar generation, and energy storage.
- Building Energy Management System (BEMS): Similar to a HEMS, a BEMS is designed for commercial and industrial buildings, offering more advanced features to manage energy use across larger facilities.
Glossary of Key Terms
Capacity: The amount of energy that an energy storage system can store, typically measured in kilowatt-hours (kWh) or megawatt-hours (MWh).
Cycles: The number of times an energy storage system can be charged and discharged. A higher cycle life indicates longer battery life.
Depth of Discharge (DoD): The percentage of a battery’s capacity that has been used. A higher DoD indicates that more of the battery’s capacity has been used, which may reduce its life cycle.
Efficiency: The ratio of energy output to energy input, typically expressed as a percentage. A higher efficiency means that less energy is lost during the storage process.
Power Rating: The maximum amount of power that an energy storage system can deliver, typically measured in kilowatts (kW) or megawatts (MW).
State of Charge (SoC): The current charge level of a battery, expressed as a percentage. A higher SoC indicates that the battery is more fully charged.
Demand Response: A strategy used by utilities and grid operators to manage peak energy demand by incentivizing consumers to reduce their energy consumption during peak hours.
Distributed Energy Resource Management System (DERMS): A system that integrates and manages distributed energy resources, such as solar panels, wind turbines, and energy storage systems, to optimize their operation and support the grid.
Grid-tied System: An energy system connected to the electrical grid, allowing it to draw energy from or send excess energy back to the grid.
Microgrid: A localized energy system that can operate independently from the main electrical grid, typically consisting of multiple distributed energy resources.
Energy Storage System (ESS): A system designed to store energy generated from various sources, such as solar or wind, for use at a later time when needed.
Energy Management System (EMS): A system that monitors, controls, and optimizes the generation, distribution, and consumption of energy within a facility or across a network of facilities.
Load Shifting: A strategy used to move energy consumption from periods of high demand to periods of low demand, improving the overall efficiency of the electrical grid.
Peak Shaving: The practice of reducing energy demand during peak hours by using stored energy or other resources, helping to alleviate stress on the grid.
Demand-Side Management (DSM): A strategy that focuses on modifying consumer energy consumption patterns to improve grid efficiency and reduce energy costs.
Smart Grid: An electrical grid that incorporates advanced technologies, such as sensors, communication networks, and automation, to optimize energy generation, distribution, and consumption.
Renewable Energy: Energy generated from sustainable resources, such as solar, wind, hydro, geothermal, and biomass, which have little to no negative impact on the environment.
Energy Density: A measure of how much energy can be stored in a given volume or mass of an energy storage material, typically expressed in watt-hours per liter (Wh/L) or watt-hours per kilogram (Wh/kg).
Round-trip Efficiency: The efficiency of an energy storage system when accounting for both charging and discharging processes, typically expressed as a percentage.
Self-discharge Rate: The rate at which a battery loses stored energy over time when not in use, usually expressed as a percentage per month.
Battery Management System (BMS): A system that monitors and controls the performance of a battery, ensuring its safe and efficient operation.
Grid Resiliency: The ability of the electrical grid to withstand and quickly recover from disturbances, such as natural disasters or equipment failures, ensuring a continuous supply of electricity to consumers.
Energy Arbitrage: The practice of buying energy at a lower price during periods of low demand and storing it for later use when prices are higher, thereby profiting from the difference in energy prices.
Ancillary Services: Support services provided by energy resources or systems to help maintain grid stability, reliability, and efficiency. Examples include frequency regulation, voltage support, and spinning reserves.
Virtual Power Plant (VPP): A network of distributed energy resources, such as solar panels, batteries, and electric vehicles, coordinated through a central control system to provide grid support and generate electricity as if they were a single power plant.
Net Metering: A billing arrangement that allows energy consumers with grid-connected distributed energy resources to receive credit for any excess electricity they generate and send back to the grid.
Energy Payback Time (EPBT): The time it takes for an energy system, such as a solar panel or wind turbine, to generate the same amount of energy required for its manufacturing, installation, and decommissioning.
Levelized Cost of Energy (LCOE): A metric used to compare the lifetime costs of different energy generation technologies, calculated as the net present value of total costs divided by the total energy output over the system’s lifetime.
Power Purchase Agreement (PPA): A contract between an energy producer and an energy buyer, specifying the terms for the sale of electricity, including price, volume, and duration.
Grid Parity: The point at which the cost of producing electricity from a renewable energy source becomes equal to or lower than the cost of generating electricity from conventional sources, such as fossil fuels.
Energy Curtailment: The reduction or restriction of energy production from renewable resources, often due to grid constraints or lack of demand.
Spinning Reserve: A reserve of generating capacity that is online and synchronized with the grid, ready to respond to changes in grid conditions and maintain system reliability.
Non-Spinning Reserve: A reserve of generating capacity that is not synchronized with the grid but can be quickly brought online in the event of a system contingency.
Frequency Regulation: The process of maintaining the electrical grid’s frequency at a constant level by adjusting the balance between electricity generation and consumption.
Voltage Support: The management of voltage levels in the electrical grid to ensure stable and reliable power delivery to consumers.
Islanding: A situation in which a portion of the grid, such as a microgrid, becomes disconnected from the main grid and continues to operate independently, maintaining power supply to its local consumers.
Time-of-Use (TOU) Pricing: A pricing structure that varies electricity rates based on the time of day, encouraging consumers to shift their energy consumption to off-peak hours when electricity demand is lower and prices are cheaper.
Demand Charge: A fee charged by some utilities based on a customer’s peak energy demand during a billing period, typically used for commercial and industrial customers to encourage more efficient energy consumption.
Grid Defection: The act of disconnecting from the main electrical grid, typically by using self-generated renewable energy combined with energy storage, to become energy-independent.
Carbon Offset: A reduction in greenhouse gas emissions achieved by supporting projects that remove or prevent the emission of an equivalent amount of carbon dioxide or other greenhouse gases, used to counterbalance one’s own carbon footprint.
Carbon Capture and Storage (CCS): The process of capturing carbon dioxide emissions from industrial processes or power generation, transporting the captured gas, and storing it in geological formations to prevent its release into the atmosphere.
Pumped Hydro Energy Storage (PHES): A large-scale energy storage technology that uses water and gravity to store and release energy. Excess electricity is used to pump water from a lower reservoir to an upper reservoir, and the stored energy is released by allowing the water to flow back down through a turbine, generating electricity.
Thermal Energy Storage (TES): A technology that stores energy in the form of heat or cold, using materials such as molten salts, phase change materials, or ice, and releases the stored energy when needed by transferring the thermal energy to or from a working fluid.
Flywheel Energy Storage (FES): A technology that stores energy in the form of kinetic energy by spinning a massive rotor at high speeds. The stored energy is released by using the rotational energy of the flywheel to generate electricity through a generator.
Compressed Air Energy Storage (CAES): A technology that stores energy by compressing air and storing it in underground reservoirs. The stored energy is released by expanding the compressed air through a turbine to generate electricity.
Demand-Side Response (DSR): A strategy that encourages energy consumers to change their consumption patterns in response to grid conditions, such as price signals or reliability concerns, to help balance supply and demand on the electrical grid.
Behind-the-Meter (BTM) Storage: Energy storage systems installed at a consumer’s location, typically for self-consumption, demand charge reduction, or backup power, rather than for grid support.
Vehicle-to-Grid (V2G): A technology that allows electric vehicles (EVs) to communicate with the electrical grid and discharge stored energy back to the grid when needed, helping to balance supply and demand and provide ancillary services.
Net-Zero Energy Building (NZEB): A building that produces as much energy as it consumes over the course of a year, typically through the use of energy efficiency measures and onsite renewable energy generation.
Decentralized Energy Generation: The generation of electricity at or near the point of consumption, as opposed to centralized generation at large-scale power plants, which relies on long-distance transmission and distribution.
Load Forecasting: The process of predicting the future electricity demand of a utility or grid, taking into account factors such as weather, seasonality, and customer behavior, to help plan and manage energy resources more effectively.
Grid Flexibility: The ability of an electrical grid to adapt to changing conditions, such as fluctuations in supply and demand or the integration of variable renewable energy sources, without compromising reliability and stability.
Energy Transition: The shift from a global energy system primarily based on fossil fuels to one that relies more heavily on renewable energy, energy efficiency, and low-carbon technologies to reduce greenhouse gas emissions and mitigate the effects of climate change.
Energy-as-a-Service (EaaS): A business model in which customers pay for energy services, such as energy generation, storage, or management, without having to invest in and maintain the underlying infrastructure themselves.
Smart Meter: An advanced electronic device that records and communicates detailed information about energy consumption, allowing for more accurate billing, better energy management, and the potential for demand response programs.
Zero Emissions Vehicle (ZEV): A vehicle that produces no tailpipe emissions during operation, typically powered by electricity or hydrogen fuel cells.
Hydrogen Storage: A method of storing energy in the form of hydrogen gas, which can be produced by electrolysis of water using electricity from renewable sources, and later used to generate electricity in fuel cells or combustion processes.
Green Hydrogen: Hydrogen produced using renewable energy sources, such as solar or wind power, resulting in minimal greenhouse gas emissions during production.
Blue Hydrogen: Hydrogen produced from natural gas through a process called steam methane reforming, combined with carbon capture and storage to reduce greenhouse gas emissions.
Grid Balancing: The process of managing the supply and demand of electricity on the grid to maintain stability, frequency, and voltage within specified limits.
Black Start Capability: The ability of a power plant to start up and generate electricity without relying on the external electrical grid, providing a crucial service in the event of a widespread power outage or grid failure.
Curtailment Management: The process of reducing or limiting the output of renewable energy generators, such as wind turbines or solar panels, in response to grid constraints or a lack of demand for the electricity being produced.
Grid Interconnection: The physical and operational connection of an energy system, such as a renewable energy generator or energy storage facility, to the electrical grid, allowing for the exchange of electricity between the system and the grid.
Stand-alone Power System (SAPS): An off-grid energy system designed to provide electricity to a specific location or facility without being connected to the main electrical grid, often relying on a combination of renewable energy sources and energy storage.
Redox Flow Battery (RFB): A type of rechargeable battery that stores energy in liquid electrolytes, which are pumped through a cell stack to produce electricity. RFBs are known for their long cycle life, scalability, and the ability to separate energy capacity from power output.
Distributed Generation (DG): The production of electricity from small-scale, decentralized energy sources, such as rooftop solar panels, small wind turbines, or combined heat and power systems, located close to the point of consumption.
Dynamic Load Management (DLM): The real-time optimization of energy consumption within a facility or across a network of facilities, using automated control systems and communication technologies to balance demand with available supply and grid conditions.
Energy Resilience: The ability of an energy system, such as a building, community, or electrical grid, to withstand and recover from disruptions, ensuring a continuous and reliable supply of energy during and after adverse events.
Integrated Resource Planning (IRP): A comprehensive process used by utilities and policymakers to evaluate and plan for future energy resource needs, considering factors such as demand forecasts, resource options, costs, environmental impacts, and policy objectives.
Transmission and Distribution (T&D) Losses: Energy losses that occur during the transmission of electricity over long distances and the distribution of electricity to end users, typically due to resistance in power lines and transformers.
Grid Modernization: The process of upgrading and enhancing the electrical grid to improve its reliability, efficiency, and resilience, and to enable the integration of new technologies, such as renewable energy, energy storage, and advanced communication systems.
Transactive Energy: A concept that involves the use of economic and control mechanisms to optimize the generation, distribution, and consumption of electricity in real-time, facilitated by advanced communication technologies and the automation of energy transactions between grid participants.
Energy Prosumer: An energy consumer who also produces and shares energy with the grid, typically through the use of renewable energy systems, such as solar panels or small wind turbines.
Energy Performance Contract (EPC): A contractual agreement between an energy service provider and a customer, where the provider guarantees specific energy savings or performance improvements, with the cost of the project often financed through the savings achieved.
Grid Inertia: The inherent ability of the electrical grid to resist sudden changes in frequency and maintain stability, provided by the rotational energy of large, synchronous generators, such as those in traditional power plants.
Synthetic Inertia: The ability of power electronic devices, such as inverters used in renewable energy systems or energy storage systems, to mimic the grid stabilizing properties of traditional generators, providing short-term frequency support in response to grid disturbances.
Battery Swapping: A system in which depleted batteries in electric vehicles or other applications are quickly exchanged for fully charged ones, reducing the time spent waiting for a battery to recharge.
Energy Hub: A centralized location where multiple forms of energy, such as electricity, heat, and cooling, are generated, stored, and distributed, often using advanced management systems and integration with the electrical grid.
Grid Edge: The interface between the electrical grid and the end users, where distributed energy resources, advanced technologies, and new market opportunities are transforming the traditional model of electricity generation, transmission, and distribution.
Community Solar: A shared solar energy system in which multiple participants, such as households or businesses, invest in or subscribe to a portion of the system’s output, enabling them to benefit from clean energy without installing solar panels on their own property.
Smart Inverter: An advanced inverter technology that can communicate with the grid, control the output of connected energy resources, and provide grid support services, such as voltage and frequency regulation, enhancing grid stability and enabling the integration of more renewable energy.
Grid-Scale Energy Storage: Large-scale energy storage systems, typically with capacities of multiple megawatt-hours or more, designed to provide grid support services, such as frequency regulation, load shifting, and backup power, to help maintain grid reliability and accommodate the integration of renewable energy sources.
Grid-Tied System: An energy generation or storage system that is connected to the main electrical grid, allowing for the exchange of electricity between the system and the grid.
Off-Grid System: An energy generation or storage system that is not connected to the main electrical grid, typically used to provide power to remote locations or for backup power during grid outages.
Renewable Energy Certificate (REC): A market-based instrument that represents the environmental benefits of one megawatt-hour of electricity generated from renewable sources, allowing consumers to support renewable energy generation and offset their own carbon emissions.
Self-Generation: The production of electricity by consumers, typically using renewable energy sources or combined heat and power systems, to meet their own energy needs and reduce reliance on the grid.
Microgrid Controller: A sophisticated management system that monitors, controls, and optimizes the operation of a microgrid, coordinating the generation, storage, and consumption of electricity to ensure reliability, efficiency, and grid support.
Energy Management System (EMS): A system that monitors, controls, and optimizes the generation, distribution, and consumption of energy within a facility or network, often using advanced data analytics and automation technologies to improve energy efficiency and reduce costs.
Grid-Forming Inverter: An advanced inverter technology that can create and maintain an electrical grid, as opposed to grid-following inverters that require a stable grid frequency and voltage to operate. Grid-forming inverters can enable the operation of islanded systems or microgrids and enhance grid stability.
Load Shifting: The practice of adjusting the timing of energy consumption to match periods of lower demand or lower prices, often using energy storage systems or demand response programs to help balance the electrical grid and reduce peak demand.
Clean Energy Standard (CES): A policy that requires a certain percentage of electricity generation to come from low- or zero-emission sources, such as renewable energy or nuclear power, helping to reduce greenhouse gas emissions and promote the adoption of clean energy technologies.
Grid Resiliency: The ability of an electrical grid to withstand and recover from disruptions, such as extreme weather events or equipment failures, ensuring a continuous and reliable supply of electricity to consumers.
Power-to-Gas (P2G): A process that converts excess electricity, typically from renewable sources, into hydrogen or other synthetic fuels, which can be stored and later used to generate electricity or as a fuel for transportation or industrial processes.
Dynamic Line Rating (DLR): A method of determining the real-time capacity of power lines based on actual weather and operating conditions, allowing for more efficient use of existing transmission infrastructure and reducing the risk of congestion or overloading.
Time-of-Use (TOU) Pricing: A variable pricing structure for electricity that reflects the cost of generating and delivering power at different times of the day, incentivizing consumers to shift their energy consumption to periods of lower demand and lower prices.
Electric Vehicle Supply Equipment (EVSE): The infrastructure and equipment required for charging electric vehicles, such as charging stations and connectors, often incorporating communication technologies to facilitate billing, grid support, and demand management.
Reactive Power: The portion of electricity that is used to maintain the magnetic fields in inductive loads, such as motors and transformers, and is essential for maintaining voltage stability on the electrical grid. Reactive power is measured in volt-amperes reactive (VAR) and is typically provided by generators, capacitors, or grid-support devices.
Islanding: The operation of a portion of the electrical grid, such as a microgrid or distributed energy resource, in isolation from the main grid, typically in response to a grid outage or other disruption, to maintain a continuous and reliable supply of electricity to the islanded area.
Renewable Portfolio Standard (RPS): A policy that requires electricity suppliers to obtain a specified percentage of their electricity from renewable sources, promoting the growth of renewable energy markets and reducing greenhouse gas emissions.
Grid Parity: The point at which the cost of generating electricity from a renewable energy source, such as solar or wind power, is equal to or lower than the cost of electricity from conventional sources, such as fossil fuels, making the renewable energy source economically competitive without subsidies.
Energy Service Company (ESCO): A company that specializes in providing energy efficiency, renewable energy, and demand management solutions to customers, often under an energy performance contract (EPC) that guarantees specific energy savings or performance improvements.
Grid Reliability: The ability of an electrical grid to provide a continuous and stable supply of electricity to consumers, maintaining the appropriate frequency, voltage, and power quality, even in the face of disturbances or fluctuations in supply and demand.
Renewable Energy Integration: The process of incorporating renewable energy sources, such as solar, wind, and hydropower, into the electrical grid, including the development of policies, infrastructure, and technologies to facilitate the efficient, reliable, and cost-effective operation of these resources.
Energy Imbalance Market (EIM): A real-time market for the trading of electricity to help balance supply and demand on the electrical grid, allowing utilities and grid operators to more efficiently manage fluctuations in generation and consumption, and to access lower-cost or cleaner sources of power.
Grid-Interactive Efficient Building (GEB): A building that integrates energy efficiency, renewable energy generation, and advanced control systems to optimize energy consumption, support the electrical grid, and reduce overall energy costs and emissions.
Energy Access: The availability and affordability of reliable and clean energy sources for households and businesses, particularly in developing countries or rural areas, to support economic development, social well-being, and the transition to a low-carbon energy system.
Energy Poverty: The lack of access to modern energy services, such as electricity and clean cooking facilities, resulting in adverse social, economic, and environmental impacts, particularly in developing countries and rural areas.
Vehicle-to-Grid (V2G): A system in which electric vehicles (EVs) can discharge electricity back to the grid during periods of high demand or when additional grid support is needed, effectively turning the vehicles’ batteries into distributed energy storage resources.
Carbon Capture and Storage (CCS): A set of technologies designed to capture carbon dioxide emissions from power plants or industrial processes and store them underground, preventing their release into the atmosphere and helping to mitigate climate change.
Behind-the-Meter (BTM): A term used to describe energy generation or storage systems that are located on the customer’s side of the utility meter, typically used for self-consumption or backup power, and potentially providing grid support services through demand response or net metering programs.
Grid Congestion: A condition in which the transmission or distribution infrastructure of the electrical grid is unable to accommodate the flow of electricity from generation to consumption points, leading to inefficiencies, higher costs, and potential reliability issues.
Distributed Energy Management: The coordination and control of multiple distributed energy resources, such as rooftop solar panels, energy storage systems, and demand response programs, to optimize their operation, reduce overall energy costs, and provide grid support services.
Battery Degradation: The gradual decline in the performance and capacity of a battery over time, typically resulting from factors such as the number of charge and discharge cycles, depth of discharge, and operating conditions, such as temperature and humidity.
Flexible Load: The portion of electricity demand that can be adjusted or shifted in response to changes in supply, grid conditions, or price signals, often through demand response programs or automated control systems, helping to balance the grid and improve overall efficiency.
Bi-directional Inverter: An inverter that can convert electricity between alternating current (AC) and direct current (DC) in both directions, enabling the charging and discharging of energy storage systems, and the integration of renewable energy sources and electric vehicles with the grid.
Net Zero Energy Building (NZEB): A building that produces as much energy as it consumes on an annual basis, typically through a combination of energy efficiency measures and on-site renewable energy generation, such as solar panels or small wind turbines.
Load Forecasting: The process of predicting future electricity demand based on historical consumption data, weather patterns, and other relevant factors, helping utilities and grid operators to plan and manage their resources more effectively.
Energy Conservation Measure (ECM): An action or technology that reduces the amount of energy required to perform a specific task or provide a specific service, improving energy efficiency and reducing overall energy consumption and costs.
Power Quality: A measure of the stability and reliability of the electricity supplied to consumers, including factors such as voltage, frequency, and waveform distortion, which can impact the performance and lifespan of electrical equipment and the overall efficiency of the grid.
Grid Defection: The decision by a consumer to disconnect from the main electrical grid and rely entirely on self-generated and stored energy, often using renewable energy sources, such as solar panels, and energy storage systems, such as batteries.
Peaker Plant: A power plant that operates only during periods of high electricity demand, often fueled by natural gas or other fossil fuels, providing additional generation capacity to help maintain grid stability and meet peak load requirements.