EFS Chapter 10 Distributed Energy Resources

Distributed Energy Resources (DERs)

Behind-the-meter generation and storage resources, typically located on the customer's premises, including demand-side management programs, demand response systems, energy storage systems, and distributed generation.

Demand-Side Management (DSM) programs

Programs designed to encourage customer energy efficiency and electrification of loads such as heat pump water heaters.

Demand Response (DR) systems

Systems that help customers shift loads to meet grid needs.

Energy Storage Systems

Electrical and thermal systems that facilitate load shifting.

Distributed Generation (DG)

Generation of electricity through rooftop photovoltaic systems and on-site combined-heat-and-power (CHP) systems.

Grid balancing

The process of continuously adjusting the supply of electricity to match the constantly changing demand.

Intermittency

The unpredictable fluctuations in power generation associated with renewable energy sources.

Bathtub analogy

An analogy used to explain the balance between supply and demand in the grid, with supply represented as uncontrollable resources and demand response as a controllable resource.

Independent System Operators (ISOs)

Organizations responsible for keeping the grid in balance using resources they control on the utility side of the meter.

Duck Curve

A graph that shows the decrease in demand during daylight hours due to the increasing supply of solar power, posing challenges for grid operators.

Ramp rates

The rate at which power generation needs to be increased or decreased within a specific time period.

Overgeneration

The situation where there is more power generation than the demand, leading to potential supply curtailment.

Combustion turbines

Power generators that use combustion to produce electricity.

Grid reliability

The ability of the electrical grid to deliver power consistently and without interruptions.

Curtailment

The act of reducing or limiting the output of a power plant, in this case, solar plants, due to grid stability concerns.

Wholesale price of electricity

The price at which electricity is sold in bulk to retailers or other large consumers.

Load shifting

Shifting the timing of electricity consumption from peak hours to non-peak hours.

Demand response

Actions taken by consumers to reduce their electricity usage during periods of high demand.

Distributed Energy Resources

Energy resources that are located close to the point of consumption, such as rooftop solar panels or small-scale wind turbines.

Demand Side Management (DSM)

Utility programs designed to encourage consumers to control their energy consumption.

Energy efficiency programs

Programs aimed at reducing energy consumption by promoting the use of more efficient technologies or practices.

Load management programs

Programs that aim to reduce peak electricity demand by shifting the timing of electricity usage.

Fuel substitution programs

Programs that encourage consumers to replace electricity with another energy source, such as natural gas.

Demand response (DR)

Actions taken to control electricity loads for short periods of time during peak demand periods.

Net Load

The total electricity demand after accounting for the effects of energy reduction strategies.

Grid stability

The ability of the electrical grid to maintain a steady and reliable supply of electricity.

Absorption cooling

A cooling technology that uses heat energy to drive the cooling process, often using natural gas as a heat source.

Utility Decoupling

A mechanism that separates utility sales from profits, eliminating incentives to sell more electricity and discouraging conservation.

DSM programs

Demand-Side Management programs that encourage customers to reduce or shift their energy loads through rebates and attractive rate structures.

Electric Rate Adjustment Mechanism (ERAM)

A mechanism that incorporates any revenue collected above or below the forecasted amount into the next year's authorized revenues, eliminating incentives to sell more kWh and reducing disincentives to reduce kWh sales.

Conventional Utility Rate Structures

Rate structures offered by utilities before the era of smart meters, which vary based on energy consumption, season, time of day, and peak power demand.

Inverted Block Rate Structure

A rate structure where rates increase with increasing demand, designed to discourage increasing consumption.

Demand Charges

Charges imposed on commercial and industrial customers based on their peak demand averaged over a 15-minute interval, in addition to energy charges.

Peak Demand

The highest level of electricity demand during a specific period, usually measured in kilowatts (kW).

Energy Storage

Technologies that store excess energy for later use, providing a potential solution to flatten demand peaks and reduce demand charges.

Load-Shifting Technologies

Technologies that allow customers to shift their energy usage to off-peak hours, reducing peak demand and potentially lowering demand charges.

Smart Meters

Advanced meters that collect detailed energy consumption data, enabling more accurate billing and the implementation of dynamic pricing structures.

Demand Response (DR) Programs

Programs that encourage customers to participate in grid balancing by adjusting their electricity usage, which can lower the cost of electricity in wholesale markets and reduce customer bills.

Advanced Metering Infrastructure (AMI)

The combination of programs and technologies that allow grid operators to communicate with and potentially control key loads on the customer's side of the meter, enabling real-time measurement and reporting of power demands.

Time-of-Use (TOU) Rates

Electricity pricing options that reflect the increased cost of generation during periods of high power demand, encouraging customers to shift their usage to off-peak times.

Distributed Energy Resources

Energy resources that are located close to the point of use, such as solar panels or wind turbines, which can help meet local energy needs and reduce strain on the grid.

Demand Charges

Charges included in utility bills for commercial and industrial customers based on their peak electricity demand, which can be adjusted based on the time of day and the cost of generation during that time.

Smart Meters

Meters that can measure and report power demands in near real time, allowing for more accurate billing and the ability to remotely connect and disconnect customers.

Demand charges

Charges based on the maximum demand for electricity during specific periods of time.

Peak demand

The highest level of electricity demand during a specific period, usually during peak hours.

Partial peak demand

The demand for electricity during periods that are not considered peak hours but still have higher demand than off-peak hours.

Off-peak

The period of time when electricity demand is at its lowest.

Rooftop photovoltaic system

A system that uses solar panels installed on rooftops to generate electricity.

Load curve

A graphical representation of the amount of electricity consumed over a specific period of time.

Distributed Energy Resources

Energy resources that are located close to the point of use, such as rooftop solar panels or small-scale wind turbines.

Demand response programs

Programs offered by utilities to incentivize customers to reduce their electricity consumption during periods of high demand.

SmartRate program

A demand response program offered by PG&E that offers discounted electricity rates in exchange for higher rates during specific hours.

SmartAC program

A demand response program offered by PG&E that allows the utility to control the air conditioning system of participating households.

Energy storage

Thermal:The use of heating and cooling systems in buildings to manage electricity demand and balance the grid.

Thermal inertia

The ability of building loads to retain and release heat over time, allowing for load management.

Electric water heaters

Water heaters that use electricity as their energy source.

Aggregated water heaters

Multiple electric water heaters that are controlled together to provide balancing of supply and demand.

Regulation market

A market where electricity providers can buy and sell regulation services to maintain grid stability.

Rooftop photovoltaic systems

Solar panel systems installed on rooftops to generate electricity.

Heat pumps

Devices that use electricity to transfer heat from one location to another, often used for heating or cooling purposes.

Critical peak pricing

A rate structure that offers reduced-cost electricity rates for most hours of the year but higher rates during critical peak hours.

Distributed Energy Resources

Energy resources that are decentralized and located close to the point of use, such as solar panels and wind turbines.

Net zero buildings

Buildings that produce as much energy as they consume, resulting in no net energy consumption from the grid.

Duck curve phenomenon

The graph of electricity demand over a 24-hour period that shows a significant drop in demand during the day and a steep increase in demand in the evening, resembling the shape of a duck.

Frequency regulation

A control strategy for water heaters that adjusts their operation to help stabilize the frequency of the electrical grid.

Time-of-use (TOU)

A control strategy for water heaters that takes advantage of the price difference between day and night utility rates to optimize their operation.

Stanford Energy System Innovations (SESI)

A system implemented by Stanford University that focuses on thermal energy storage and photovoltaics to meet the campus's electricity and heating needs.

Thermal energy storage

The storage of thermal energy in a medium, such as water or ice, for later use in heating or cooling applications.

Ice storage

A method of thermal energy storage that involves making ice at night when electricity rates are low and using it for cooling during peak demand periods.

Load shifting

Shifting the timing of electricity consumption from peak demand periods to off-peak periods to reduce costs and strain on the electrical grid.

Electrical energy storage

Systems that store electricity for later use, providing benefits such as peak shaving, grid stability, and integration of renewable energy sources.

Energy for Sustainability

The concept of using energy sources and systems that can be sustained over the long term without depleting natural resources or causing harm to the environment.

Batteries

Devices that store electrical energy and can provide backup power during outages or be used to store excess power generated by renewable energy systems.

Net metering

A billing arrangement where customers with rooftop solar systems can receive credit for any excess power they generate and feed back into the grid.

Reverse power flows

When customers with rooftop solar systems generate more power than they need, causing the meter to spin backwards and potentially creating imbalances in the local distribution system.

Energy storage technologies

Methods and technologies used to store large-scale energy, including pumped hydro, compressed air energy storage, batteries, flywheels, and supercapacitors.

Pumped hydro

A method of energy storage that involves pumping water uphill into a reservoir during low-demand periods and releasing it through turbines during high-demand periods.

Lithium-ion batteries

A type of battery technology commonly used in electric vehicles and home energy storage systems, known for their high energy density and long cycle life.

Amp-hour (Ah) capacity

A measure of a battery's capacity to deliver a certain amount of current over a specified number of hours.

Series and parallel battery combinations

Wiring batteries in series increases the voltage, while wiring them in parallel increases the amp-hour capacity.

Applications of stationary storage

Various uses of energy storage systems, including load shifting and peak shaving, coupling with photovoltaics, flexible EV charging schedules, load aggregation for grid services, and solar home systems for developing countries.

Distributed Energy Resources

Resources that generate electricity or provide energy services and are located close to the point of use, such as solar panels, wind turbines, and energy storage systems.

Vehicle-to-Grid (V2G) systems

Systems that allow electric vehicles to not only consume energy from the grid but also feed energy back into the grid, enabling them to act as mobile energy storage devices.

Ancillary Services

Services provided by distributed energy resources, such as frequency regulation and demand response, that help maintain the stability and reliability of the electrical grid.

Load Shifting

The practice of shifting electricity consumption from high-demand periods to low-demand periods, often using energy storage systems like batteries.

Battery Round-Trip Efficiency

The efficiency of a battery system in terms of how much energy can be stored and then discharged back into the grid.

Off-Peak Electricity Costs

The cost of electricity during periods of low demand, typically when electricity rates are lower.

On-Peak Electricity Costs

The cost of electricity during periods of high demand, typically when electricity rates are higher.

Aggregating Loads

Combining multiple energy resources, such as electric vehicles or battery systems, to provide services to the electrical grid, such as frequency regulation and demand response.