Sources of energy

The chances of a sustainable supply with energy – Part 2

15 Jährlicher Energiefluss [EJ/a] # Annual energy flow [EJ/a]

16 Jährlicher Wasserkreislauf [Gt H₂O/a] # The annual water cycle [Gt H₂O/a]

17 Jährlicher Kohlenstoffkreislauf [Gt C/a] # The annual carbon cycle [Gt C/a]

18 Natürliche Energiewandlungsprozesse C_n # Natural energy-conversion processes C_n

19 Technische Energiewandlungsprozesse C_t (Ė_js2® Ė_kr) # Technical energy-conversion processes C_t (Ė_js2® Ė_kr)

20 Natürliches Angebot und Nutzbarkeit erneuerbarer Energien (Welt) [EJ/a] # Natural availability and usability of renewable energy (world) [EJ/a]

21 Weltweite Ausgaben für Energieforschung und -entwicklung sowie Prototypenbau in den Mitgliedsstaaten der International Energy Agency (ohne Polen, Slowakei und Tschechien, Preisbasis und Umrechnungskurse 2010) # Global expenditure on energy Research & Development and prototyping in the member states of the International Energy Agency (not including Poland, Slovakia or the Czech Republic); price basis and exchange rates: 2010

Kraftwerk Boxberg # Power station Boxberg

Summary: After dealing with the history of energy supply with various sources, analyzing the present and future energy requirement and investigating the various reserves and resources in the first part of this article, the energy flows are shown and analyzed in the second part. The focus of the comprehensive conclusions, which finally summarize and evaluate the essential statements of both parts, is mainly on the future possibilities of development and chances. The scenarios of a future energy supply are linked taking into account different social aspects and developments.

5 Energy flows

Human life on the planet earth is possible only within an extremely narrow „temperature window“. Without the flows of energy from external and internal energy sources which supply the surface of the earth with energy, and without the conversion and use of these energy flows in mass flows, temperatures on earth would be those of outer space. Incoming and outgoing energy flows are therefore in a sensitive state of equilibrium.

The incoming energy flows originate primarily from the sun (solar radiation), the earth itself (heat generated by radioactive decay and residual heat from...