Energy flow

« Back to Glossary Index

En­er­gy flow de­scribes the process of trans­fer­ring phys­i­cal en­er­gy be­tween dif­fer­ent tech­ni­cal or nat­ur­al sys­tems (al­so en­er­gy trans­fer). The en­er­gy flow is mea­sured as phys­i­cal pow­er en­er­gy per time. As a re­sult, it has dif­fer­ent units de­pend­ing on the field of application:

  • Watt (W)
  • Joules per sec­ond (J/s)
  • Joules per day (J/d)
  • Horse­pow­er (hp)
  • Kilo­watt hours per day (kWh/d)
  • Hard coal units per year (tSKE/a)

In the ex­pla­na­tions that fol­low, we most­ly ad­dress the tech­ni­cal flow of energy.

Physical energy

The term en­er­gy, which comes from the Greek and trans­lates as “act­ing force,” is un­der­stood in physics to mean the abil­i­ty to per­form work, emit heat, or ra­di­ate light. If we ap­ply this de­f­i­n­i­tion to every­day sit­u­a­tions, it means that we need en­er­gy to move ob­jects from A to B, to warm up our home in win­ter, or to pro­duce light in our head­lights when we dri­ve our car at night.

Primary energies

Pri­ma­ry en­er­gies are en­er­gies that oc­cur in our na­ture and do not have to be pro­duced or con­vert­ed through work steps. These en­er­gy sources are so­lar ra­di­a­tion, wind, hy­dro­elec­tric pow­er, hard coal, lig­nite, crude oil, nat­ur­al gas, etc.. In our en­er­gy econ­o­my, they serve as the ba­sis for the tech­ni­cal flow of en­er­gy in in­dus­try, ser­vices, trans­port and for end consumers.

Secondary energies

When pri­ma­ry en­er­gy is con­vert­ed in­to a new form of en­er­gy, it is re­ferred to as sec­ondary en­er­gy. Ex­am­ples of the con­ver­sion of pri­ma­ry to sec­ondary energy:

  • So­lar ra­di­a­tion, wind and hy­dro­elec­tric pow­er are con­vert­ed in­to electricity
  • Hard coal and lig­nite be­come bri­quettes, coke and town gas
  • Pe­tro­le­um be­comes gaso­line, diesel fu­el and heat­ing oil
  • Coal, oil and nat­ur­al gas be­come electricity

Elec­tri­cal en­er­gy (elec­tric­i­ty) has es­tab­lished it­self as the most im­por­tant sec­ondary en­er­gy. Due to the world­wide elec­tric­i­ty net­work, this en­er­gy is avail­able very quick­ly at the nec­es­sary location.

What other energy flows are there?

Be­sides the tech­ni­cal en­er­gy flow, we al­so have the nat­ur­al en­er­gy flow. This refers to the eco­log­i­cal en­er­gy flow. It deals with the whole process of en­er­gy pro­duc­tion of plants by sun­light and the re­sult­ing food chain.

« Zurück zum Glossar Index
Scroll to Top