Electric energy consumption
The demand for electrical energy, including power consumption, power requirements, or power consumption, identifies the amount of electrical energy that is converted from electrical devices during a defined period of time.
The converted electrical energy W (of English work = work) is measured in watt-seconds or kilowatt hours. It is the entire electrical work that flows over the period, t in the considered power P. At a constant demand the converted energy is the product of the electric power P with the elapsed time t:
Example: A hair dryer takes 2000 watts ( 2 kW) electric power. If the hair dryer for half an hour (0.5 h) operated long, the demand for electrical power is 2 kW · h 0,5 = 1 kWh ( kilowatt- hour). In the European network at 230 volts, a current flows from 2 kW / 230 V ≈ 8.7 A ( amps).
Daily curve of the electric energy demand
The demand for electrical energy is subject to both diurnal and seasonal variations. Days past considered to result in peak demand made between 7 und 14 clock clock and in the evenings. In the late night hours the demand reaches a minimum. In winter, a higher demand for electrical energy arises due to the shorter time of day (increased lighting expense) on the one hand and the lower temperatures ( electric heating) on the other hand one.
For permanent cover the requirements, it is necessary also to be able to handle the peak demand safe in addition to the basic requirements. In this context one also speaks of base load, medium load and peak load.
For power plants that supply the base load, there are those types that cost all year, apart from inspection periods, work ( coal, nuclear, hydroelectric power plants). In Austria, mostly as hydroelectric power plants and storage plants this task. In the Central European section these types cover about 30 % of energy needs.
Among the medium-load power plants include coal dust, oil, gas and storage plants. Characteristic of this type is the ability to respond flexibly to fluctuations in demand larger scale. They cover about 40 % of the electrical energy needs.
However, in order to compensate for fluctuations in demand, it is necessary peak load power plants to operate as gas turbines, oil, storage, pumped storage power plants. Such plants are usually set for a few short hours of operation to meet the short-term high energy requirements.
Pumped storage permit in this context, the most effective adaptation to the increased demand for electrical energy, as can be pump-turbines within a few seconds of pump operation transfer in turbine operation. To ensure a continuous and uniform supply in the power plants automation systems are operated and this is done by integration of the systems in a nationwide composite system.
In 2011, the annual gross electricity consumption amounted to 606.8 billion kWh in Germany at a gross electricity production of 613.1 billion kWh. The contribution of renewable energies to this was over 20%. The following table gives an overview of the development of gross electricity consumption and the share of renewable energies since 1991:
On the net electricity consumption in 2011 ( 535.2 TWh ) related to the individual areas following shares:
- Industry: 46.6 % ( 249.6 TWh)
- Households: 25.5 % ( 136.6 TWh)
- Trade & Industry: 14.3 % ( 76.5 TWh)
- Public facilities: 8.8% ( 46.9 TWh)
- Traffic: 3.1% ( 16.6 TWh)
- Agriculture: 1.7% (9.0 TWh)
According to calculations by the Federal Environment Agency of electrical energy sales of 1995 has increased by eleven percent to 2000. He then fell to 2005 by about seven percent
Electricity consumption in private households
In private households in electrical energy sales has risen sharply by electrical appliances according to the International Energy Agency ( IEA). Decreases were in washing machines and fridges, while the electric energy sales through television, air conditioning and computer increased dramatically. This is a consequence of the percentage increase in total energy consumption. Between 1990 and 2004 this has increased from 15 to 20 percent.
The distribution of electricity in private households has been determined on the basis of consumption data, the Energy Agency of North Rhine -Westphalia has raised from 380 370 A -to six -person households who had participated in the counseling program " current checks for households," the NRW Energy Agency. Accordingly, the two fields of information and entertainment electronics " office equipment " and "TV / Audio" at the current intensive and take a quarter of the electricity consumption in private households a. Four other functional areas take depending around 10% a: hot water, cooling, lighting and cooking. The amount of electricity consumption could be determined depending on the household size, the type of water heating ( with or without electricity ) has a significant influence (see Table ).
The Institute for Energy and Environmental Research Heidelberg calls, inter alia, the following reasons for the increase in demand for electrical energy in spite of increasingly efficient devices:
- Reservations about new techniques, such as energy-saving lamps
- Increasing demands for comfort
- Larger average residential
- Increased use of larger and larger devices as well as the steadily declining cost of household goods and electronics
The increasing use of heat pumps for household and building heating as a substitute for fossil-fueled heating causes besides the saving of fossil primary energy an increase in power consumption.
In comparison, the EU countries and the conversion to residents is common in addition to the total consumption of electricity. These comparative size indicates the total consumption per capita and is to be distinguished from private consumption, which is significantly lower. In total electricity consumption per capita in 2011 was Finland in the EU countries, by far the leader with 15,372 kWh / a The EU average 6201 kWh / year were consumed per capita, Germany was placed with 6648 kWh / a slightly above average, Italy with 5187 kWh / a significantly lower. In Austria, the total electricity consumption per capita in 2011 was 7762 kWh / a, France at 7042 kWh / a, Greece at 6010 kWh / a and in Poland at 3433 kWh / a
Needs of individual electrical appliances
A hair dryer with 2000 watts, which is used 5 minutes a day in the year requires about 61 kWh of electrical energy, inflicting a labor cost of 25 cents / kWh costs about 15 euros a year.
With only 150 watts of power, but runs 2 hours a day and thus requires about 110 kWh of electrical energy per year and about 28 euros in the year caused Compared to the flat-screen TV at a cost ( at an operating cost of 25 cents / kWh).
Comparing the oven with 4000 watts of power, which is open daily for half an hour in operation and so already requires 730 kWh of electrical energy per year, which accounts for about 183 euros a year ( at a working price of 25 cents / kWh).
A 1200 -watt electric kettle that is used every day for 10 minutes, consumes 73 kWh per year, causing work at a price of 25 cents / kWh electricity cost of around 18 euros per year.
In December 2012, informed the think tank Agora energy revolution ' with that in cooperation with the states of Bavaria and Baden- Württemberg a study on load management (such as control large demand their demand so that aggregate demand and supply are in harmony ) will create.
On June 5, 2013 expressed Siemens CEO Peter Löscher, Germany could save 2030 150 billion euros, if the energy change would be better managed. He introduced a " three-point plan" ( 1 reconstruction of the electricity market; 2 increase energy efficiency; 3rd European coordination of energy policy ).
Löscher called a Siemens carried out jointly with the consulting firm McKinsey study, 20 ( inter) portrays national solutions along the energy value chain - from power generation to distribution to increase energy efficiency in buildings, industry and transport. Accordingly, the U.S. leader in the targeted control of power consumption over a temporary reduction in demand for electricity.