Introduction and Structure - Renewable Energy: Technology, Economics and Environment - page 4

are thus unlimited in human (time) dimensions - they are nevertheless exhaustible
(e.g. burn-out of the sun sometime in the future).
The available energies or energy carriers can be further subdivided into fossil
biogenous, fossil mineral and renewable energies or fossil biogenous, fossil min-
eral and renewable energy carriers.
− Fossil biogenous energy carriers primarily include the energy carriers coal (lig-
nite and hard coal) as well as liquid or gaseous hydrocarbons (such as crude oil
and natural gas). A further differentiation can be made between fossil bioge-
nous primary energy carriers (e.g. lignite) and fossil biogenous secondary en-
ergy carriers (e.g. gasoline, Diesel fuel).
− Fossil mineral energy carriers comprise all substances that provide energy de-
rived from nuclear fission or fusion (such as uranium, thorium, hydrogen).
− The term renewable energy refers to primary energies that are regarded as in-
exhaustible in terms of human (time) dimensions. They are continuously gen-
erated by the energy sources solar energy, geothermal energy and tidal energy.
The energy produced within the sun is responsible for a multitude of other
renewable energies (such as wind and hydropower) as well as renewable
energy carriers (such as solid or liquid biofuels). The energy content of the
waste can only be referred to as renewable if it is of non-fossil origin (e.g.
organic domestic waste, waste from the food processing industry). Properly
speaking, only naturally available primary energies or primary energy carriers
are renewable but not the resulting secondary or final energies or the related
energy carriers. For instance, the current generated from renewable energies by
means of a technical conversion process itself is not renewable, since it is only
available as long as the respective technical conversion plant is operated.
However, in everyday speech secondary and final energy carriers derived from
renewable energy are often also referred to as renewable.
1.1.2 Energy consumption
In 2005, the worldwide consumption of fossil primary energy carriers and of hy-
dropower amounted to approximately 441 EJ /1-3/. Roughly 28 % of this overall
energy consumption accounts for Europe and Eurasia, approximately 27 % for
North America, about 5 % for Central and South America, roughly 5% for the
Middle East, approximately 3 % for Africa and about 32% for Asia and the Pa-
cific region (primarily Australia and New Zealand). North America, Europe and
Eurasia as well as Asia and the Pacific region consume about 90 % of the cur-
rently used primary energy derived from fossil energy carriers and hydropower.
Fig. 1.2 illustrates the evolution of primary energy consumption of fossil en-
ergy carriers and hydropower according to regions over the past 40 years. Accord-
ing to the figure, the worldwide primary energy consumption has increased by
more than the factor of 2.5 over this period of time. All illustrated regions show a