Distributed generation, also distributed energy, on-site generation (OSG), or district/decentralized energy, is electrical generation and storage performed by a variety of small, grid-connected or distribution system-connected devices referred to as distributed energy resources (DER).
An electricity meter, electric meter, electrical meter, energy meter, or kilowatt-hour meter is a device that measures the amount of electric energy consumed by a residence, a business, or an electrically powered device.
A storage heater or heat bank (Australia) is an electrical heater which stores thermal energy during the evening, or at night when electricity is available at lower cost, and releases the heat during the day as required. Alternatively, solar storage heaters are designed to store solar energy as heat, to be released during the night or other periods where it is required, often making it more cost effective than selling surplus electricity to the grid and buying it back at night.
Energy demand management, also known as demand-side management (DSM) or demand-side response (DSR), is the modification of consumer demand for energy through various methods such as financial incentives and behavioral change through education.
Grid energy storage is a collection of methods used for energy storage on a large scale within an electrical power grid. Electrical energy is stored during times when electricity is plentiful and inexpensive or when demand is low, and later returned to the grid when demand is high, and electricity prices tend to be higher.
Peaking power plants, also known as peaker plants, and occasionally just "peakers", are power plants that generally run only when there is a high demand, known as peak demand, for electricity. Because they supply power only occasionally, the power supplied commands a much higher price per kilowatt hour than base load power. Peak load power plants are dispatched in combination with base load power plants, which supply a dependable and consistent amount of electricity, to meet the minimum demand.
Demand response is a change in the power consumption of an electric utility customer to better match the demand for power with the supply. Until the 21st century decrease in the cost of pumped storage and batteries electric energy could not be easily stored, so utilities have traditionally matched demand and supply by throttling the production rate of their power plants, taking generating units on or off line, or importing power from other utilities. There are limits to what can be achieved on the supply side, because some generating units can take a long time to come up to full power, some units may be very expensive to operate, and demand can at times be greater than the capacity of all the available power plants put together. Demand response, a type of energy demand management, seeks to adjust in real-time the demand for power instead of adjusting the supply.
Economy 7 is the name of a differential tariff provided by United Kingdom electricity suppliers that uses base load generation to provide cheap off-peak electricity during the night.
A virtual power plant (VPP) is a cloud-based distributed power plant that aggregates the capacities of heterogeneous distributed energy resources (DER) for the purposes of enhancing power generation, trading or selling power on the electricity market, and demand side options for load reduction.
Dynamic Demand is the name of a semi-passive technology to support demand response by adjusting the load demand on an electrical power grid. It is also the name of an independent not-for-profit organization in the UK supported by a charitable grant from the Esmée Fairbairn Foundation, dedicated to promoting this technology. The concept is that by monitoring the frequency of the power grid, as well as their own controls, intermittent domestic and industrial loads switch themselves on/off at optimal moments to balance the overall grid load with generation, reducing critical power mismatches. As this switching would only advance or delay the appliance operating cycle by a few seconds, it would be unnoticeable to the end user. This is the foundation of dynamic demand control. In the United States, in 1982, a (now-lapsed) patent for this idea was issued to power systems engineer Fred Schweppe. Other patents have been issued based on this idea.
Zellweger is the brand name of an electric switching device also known as a Ripple Control Receiver used to control off-peak electrical loads such as water heaters by switching these loads OFF over peak energy use times of the day and switching them ON after peak energy use times of the day, hence the term 'off peak' control. It is an example of carrier current signaling. The Ripple Control Signal is generated at substations owned by Electricity Supply Authorities connected to the High Voltage transmission grid and injected into the Medium Voltage transmission grid at 11kV, 22kV, 33kV and 66kV, through a Coupling Cell consisting of a tuned L-C circuit. The Coupling Cell enables the Ripple Control Frequency to be superimposed on the 50 Hertz (Hz) mains frequency, which promulgates into the 415 V 3 phase power distribution lines providing energy to industrial and domestic customers of the Electricity Supply Authority. To avoid problems with other equipment connected to the distribution system ; i.e. industrial machinery and domestic appliances, the ripple frequency is selected to be offset from the third harmonic and its multiples, typically starting at 167 Hz and including, 217, 317, 425, 750, 1050, 1650. The choice of frequency depends upon the density of the load into which the ripple frequency is to be injected and the length of the distribution
Economy 10 is the name of a tariff provided by United Kingdom electricity suppliers created in 2004. Similar to the Economy 7 this is designed to be used with high thermal mass heating such as storage heaters, underfloor heating, and is also used with electrical boilers driving radiators or water-based heat stores.
A load-following power plant, regarded as producing mid-merit or mid-priced electricity, is a power plant that adjusts its power output as demand for electricity fluctuates throughout the day. Load-following plants are typically in between base load and peaking power plants in efficiency, speed of start-up and shut-down, construction cost, cost of electricity and capacity factor.
Load management, also known as demand-side management (DSM), is the process of balancing the supply of electricity on the network with the electrical load by adjusting or controlling the load rather than the power station output. This can be achieved by direct intervention of the utility in real time, by the use of frequency sensitive relays triggering the circuit breakers, by time clocks, or by using special tariffs to influence consumer behavior. Load management allows utilities to reduce demand for electricity during peak usage times, which can, in turn, reduce costs by eliminating the need for peaking power plants. In addition, some peaking power plants can take more than an hour to bring on-line which makes load management even more critical should a plant go off-line unexpectedly for example. Load management can also help reduce harmful emissions, since peaking plants or backup generators are often dirtier and less efficient than base load power plants. New load-management technologies are constantly under development — both by private industry and public entities.
A smart grid is an electrical grid which includes a variety of operation and energy measures including:
Differential tariff is an example of demand side management where the price per unit of energy varies with the consumption. If a power utility uses differential tariff, it may change the rate per kWH of energy used during different times, such as raising the price during times of high energy consumption and lowering the price during times of low energy consumption. This helps balance the rate at which power is used and the rate at which power is created.
An electrical grid is an interconnected network for electricity delivery from producers to consumers. Electrical grids vary in size and can cover whole countries or continents. It consists of:
Tankless water heaters — also called instantaneous, continuous flow, inline, flash, on-demand, or instant-on water heaters — are water heaters that instantly heat water as it flows through the device, and do not retain any water internally except for what is in the heat exchanger coil unless the unit is equipped with an internal buffer tank. Copper heat exchangers are preferred in these units because of their high thermal conductivity and ease of fabrication. However, copper heat exchangers are more susceptible to scale buildup than stainless steel heat exchangers.
Home energy storage devices store electricity locally, for later consumption. Electrochemical energy storage products, also known as "Battery Energy Storage System", at their heart are rechargeable batteries, typically based on lithium-ion or lead-acid controlled by computer with intelligent software to handle charging and discharging cycles. Companies are also developing smaller flow battery technology for home use. As a local energy storage technologies for home use, they are smaller relatives of battery-based grid energy storage and support the concept of distributed generation. When paired with on-site generation, they can virtually eliminate blackouts in an off-the-grid lifestyle.
A mini-grid is an aggregation of loads and one or more energy sources operating as a single system providing electric power and possibly heat isolated from a main power grid. A modern mini-grid may include renewable and fossil fuel-based generation, energy storage, and load control. A mini grid can be fully isolated from the main grid or interconnected to it. If it is interconnected to the main grid, it must also be able to isolate (“island”) from the main grid and continue to serve its customers while operating in an island or autonomous mode. Mini-grids are used as a cost-effective solution for electrifying rural communities where a grid connection is challenging in terms of transmission and cost for the end user population density, with mini grids often used to electrify rural communities of a hundred or more households that are 10 km or more from the main grid.
