Energy flow (ecology)

Energy flow is the process of passing physical energy between different technical or natural systems. In power engineering, also referred to as energy transfer. The strength of an energy flow is an accomplishment.

Ecological and technical energy flow

In ecology, energy flow denotes the energy transfer and energy conversion of irradiated solar energy ( or of the present chemical energy ) in the ecosystem of the biomass of the primary producers and the subsequent food chain ( consumer and Destruentenkette ). The energy flow is like the physical performance measured as energy per time period. He has therefore, for example, one of the following units whose unit symbols are not to be written in square brackets (DIN 1313):

• W ( = W ),
• J / s (= joules per second, 1 J / s = 1 W),
• J / D (= Joule per day),
• PS (traditional technical unit horsepower, 1 hp = 735.5 W)

In the energy field more units shall be used, eg

• KWh / d ( = kilowatt hours per day) or
• Tce / a ( = tons of coal equivalent per year)

If the energy flow is not specified for an individual, a population or a technical system, but for a distributed energy source (eg in primary production of a corn field in the art in energy conversion of a solar collector ), so you are a relative to the area performance, eg

• J / ( m2 × d ) (= joules per square meter per day) or
• W/m2 ( = watts per square meter ).

In technology, energy flow, in the same units as in ecology (see energy flow diagram) are described, for example, the flow of energy from hydropower (primary energy as potential energy of dammed water ) about the resulting generated electrical energy ( secondary energy or energy ) and the supply to the traction power for conversion into the kinetic energy of the trains (final energy and useful energy ). At this energy transfer is often a large part of the energy, for example by power loss, free as waste heat.

Both energy flow systems, the ecological and technical, is the principle of multiple energy conversion based that operates at each conversion only with a certain efficiency. With each transition from one form of energy into another heat energy is released. Ecological systems show the transition from one trophic level to the next (eg, the transition from herbivores to carnivores ) in the course of a food chain efficiencies often only around 10 % or less. The efficiency of the transformation along technical energy flows may be very different.

In the real world, the ecological and technical energy flows are partially cross-linked with each other, for example in the use of hydropower, or biomass as primary energy, or - in the opposite direction - in the use of traction force a donkey to drive a water conveyor system.

Importance of ecological energy flow

Ecological energy flows can be created for individuals, for populations, ecosystems, or even as a power circuit for the entire earth and allow the calculation of complete energy balances. As a result of the energy flow through the various trophic levels of ecosystems, ultimately, the entire incident and assimilable by the green plant light energy in the form of heat in time-delayed form is released back into the environment. By means of the complex features of living things through compartments and by enzyme chain whose activity can be controlled by the organism, energy cascades are implemented that make the various earthly life processes and also the principle of the food chain by gradual and stepwise conversion, storage or release of energy possible.

Magnitude of the energy flow

The flow of energy through a central European forest ecosystem is known as gross primary production (ie biomass production without consideration of the respired by the metabolism of the plant portion ) about 1 W/m2.

The energy flow of an adult human is of the order of 100-150 W. This corresponds to about 3 kWh per day or 10 MJ per day or 4 GJ per year. This energy used by the person for the sum of all its metabolic activities, for its fabric production, movements and physical work, for his communication and heat production. The total energy consumption per person is located in Central Europe today, however, significantly (about 20-30 times ) higher as energy in the form of oil, timber, electricity, etc., for transport, heating, industrial production and other is expended.

Energy flow and material cycle

The primary energy in ecosystems need not necessarily come from the radiant energy of light, but may also by biochemical reactions (eg, oxidation of sulfides ) will be paid. This has esp. a meaning in oxygen-free regions of the world (eg hydrothermal vents in the ocean ). A well-functioning energy flow in ecosystems is the energetic foundation that they can exist in the long term with their world of organisms and that an ecological material cycle is possible.