Energiankulku

Energiankulku is a concept used to describe the passage of energy through a system, most commonly in ecology to trace how energy from the environment flows through a community of organisms. The term combines energia (energy) and kulku (flow) in Finnish.

In ecological contexts, energy typically enters as solar radiation and is captured by photosynthetic organisms (producers). The chemical energy stored is transferred to herbivores and then to carnivores, with most of the energy lost as heat through metabolic processes at each transfer, according to the ecosystem's trophic structure. The efficiency of transfer between trophic levels is variable but often ranges from a few percent to around 20 percent, leading to an energy pyramid. Key measures include gross primary productivity, net primary productivity, and net ecosystem production, expressed in energy units such as kilojoules per square meter per year or joules per square meter per second. Energy budgets can be summed to assess ecosystem functioning, constraints, and resilience.

In physics or engineering, energiankulku can also refer to the general accounting of energy flow in a system: input, storage, conversion, transfer, and losses, described by energy balance equations and the first law of thermodynamics. It emphasizes conservation of energy and the pathways by which energy is transformed.

Energiankulku is used in both scientific disciplines to analyze how energy is supplied, transformed, and ultimately dissipated, providing a framework for understanding system limits, efficiency, and sustainability.