Full Load hour is a measure of the degree of utilisation of a technical system. [1] [2] [3] Full load hours refer to the time for which a plant would have to be operated at nominal power in order to convert the same amount of electrical work as the plant has actually converted within a defined period of time, during which breaks in operation or partial load operation can also occur. The figure usually refers to a period of one calendar year and is mainly applied to power plants.
The annual utilisation rate or capacity factor derived from the number of full-load hours is the relative full-load utilisation in a year, i.e. the number of full-load hours divided by 8760 hours, the number of hours in a year with 365 days.
Typically technical plants are not constantly operated at full load, but depending on various factors (see below) the system can be under a partial load. The total work converted by the plant in a year is therefore less than the maximum possible work in the same period.
The degree of utilisation of a technical plant can be expressed in full load hours if a nominal capacity can be specified and an adequate conversion from partial load operation to nominal load operation exists (e.g. on the basis of the amount of energy or material converted).
The number of full load hours of a plant varies from year to year due to different technical inspection durations, power plant operating schedules, maintenance, unplanned disturbances and outages and due to different weather conditions, especially for renewable energy sources.
The value must not be confused with operating hours. These refer to the entire period of time during which the system has been operated and can has been operated and may include periods of partial load operation.
The number of full load hours of a generator is calculated by dividing the (expected) annual energy output (e.g. in kWh) by the nominal power of the generator (e.g. in kW or kWp).
It indicates how many hours the plant would have run to achieve the same annual energy production if it had been running either at full load or otherwise have been completely inactive.
Electric power transmission is the bulk movement of electrical energy from a generating site, such as a power plant, to an electrical substation. The interconnected lines that facilitate this movement form a transmission network. This is distinct from the local wiring between high-voltage substations and customers, which is typically referred to as electric power distribution. The combined transmission and distribution network is part of electricity delivery, known as the electrical grid.
A kilowatt-hour is a non-SI unit of energy: one kilowatt of power for one hour. It is equivalent to 3.6 megajoules (MJ) in SI units. Kilowatt-hours are a common billing unit for electrical energy supplied by electric utilities. Metric prefixes are used for multiples and submultiples of the basic unit, the watt-hour.
A nuclear power plant (NPP) is a thermal power station in which the heat source is a nuclear reactor. As is typical of thermal power stations, heat is used to generate steam that drives a steam turbine connected to a generator that produces electricity. As of 2022, the International Atomic Energy Agency reported there were 422 nuclear power reactors in operation in 32 countries around the world, and 57 nuclear power reactors under construction.
Wave power is the capture of energy of wind waves to do useful work – for example, electricity generation, water desalination, or pumping water. A machine that exploits wave power is a wave energy converter (WEC).
The spark spread is the theoretical gross margin of a gas-fired power plant from selling a unit of electricity, having bought the fuel required to produce this unit of electricity. All other costs must be covered from the spark spread. The term was first coined by Tony West's trading team on the trading floor of National Power Ltd in Swindon, UK during the late 1990s and quickly came into common usage as other traders realised the trading and hedging opportunities.
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 seeks to adjust the demand for power instead of adjusting the supply.
Electric power is the rate at which electrical energy is transferred by an electric circuit. The SI unit of power is the watt, one joule per second. Standard prefixes apply to watts as with other SI units: thousands, millions and billions of watts are called kilowatts, megawatts and gigawatts respectively.
A diesel generator (DG) (also known as a diesel Genset) is the combination of a diesel engine with an electric generator (often an alternator) to generate electrical energy. This is a specific case of engine generator. A diesel compression-ignition engine is usually designed to run on diesel fuel, but some types are adapted for other liquid fuels or natural gas.
The net capacity factor is the unitless ratio of actual electrical energy output over a given period of time to the theoretical maximum electrical energy output over that period. The theoretical maximum energy output of a given installation is defined as that due to its continuous operation at full nameplate capacity over the relevant period. The capacity factor can be calculated for any electricity producing installation, such as a fuel consuming power plant or one using renewable energy, such as wind or the sun. The average capacity factor can also be defined for any class of such installations, and can be used to compare different types of electricity production.
To balance the supply and demand of electricity on short timescales, the UK National Grid has contracts in place with generators and large energy users to provide temporary extra power, or reduction in demand. These reserve services are needed if a power station fails for example, or if forecast demand differs from actual demand. National Grid has several classes of reserve services, which in descending order of response time are: Balancing Mechanism (BM) Start-Up, Short-Term Operating Reserve, Demand Management and Fast Reserve.
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.
A photovoltaic system, also PV system or solar power system, is an electric power system designed to supply usable solar power by means of photovoltaics. It consists of an arrangement of several components, including solar panels to absorb and convert sunlight into electricity, a solar inverter to convert the output from direct to alternating current, as well as mounting, cabling, and other electrical accessories to set up a working system. It may also use a solar tracking system to improve the system's overall performance and include an integrated battery.
The nominal power is the nameplate capacity of photovoltaic (PV) devices, such as solar cells, modules and systems, and is determined by measuring the electric current and voltage in a circuit, while varying the resistance under precisely defined conditions. The nominal power is important for designing an installation in order to correctly dimension its cabling and converters.
Concentrated solar power systems generate solar power by using mirrors or lenses to concentrate a large area of sunlight into a receiver. Electricity is generated when the concentrated light is converted to heat, which drives a heat engine connected to an electrical power generator or powers a thermochemical reaction.
In electrical engineering the load factor is defined as the average load divided by the peak load in a specified time period. It is a measure of the utilization rate, or efficiency of electrical energy usage; a high load factor indicates that load is using the electric system more efficiently, whereas consumers or generators that underutilize the electric distribution will have a low load factor.
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:
A wind turbine is a device that converts the kinetic energy of wind into electrical energy. As of 2020, hundreds of thousands of large turbines, in installations known as wind farms, were generating over 650 gigawatts of power, with 60 GW added each year. Wind turbines are an increasingly important source of intermittent renewable energy, and are used in many countries to lower energy costs and reduce reliance on fossil fuels. One study claimed that, as of 2009, wind had the "lowest relative greenhouse gas emissions, the least water consumption demands and the most favorable social impacts" compared to photovoltaic, hydro, geothermal, coal and gas energy sources.
Nameplate capacity, also known as the rated capacity, nominal capacity, installed capacity, maximum effect or Gross Capacity, is the intended full-load sustained output of a facility such as a power station, electric generator, a chemical plant, fuel plant, mine, metal refinery, and many others. Nameplate capacity is the theoretical output registered with authorities for classifying the unit. For intermittent power sources, such as wind and solar, nameplate power is the source's output under ideal conditions, such as maximum usable wind or high sun on a clear summer day.
Ancillary services are the services necessary to support the transmission of electric power from generators to consumers given the obligations of control areas and transmission utilities within those control areas to maintain reliable operations of the interconnected transmission system.
Variable renewable energy (VRE) or intermittent renewable energy sources (IRES) are renewable energy sources that are not dispatchable due to their fluctuating nature, such as wind power and solar power, as opposed to controllable renewable energy sources, such as dammed hydroelectricity or biomass, or relatively constant sources, such as geothermal power.
