Evolution of Energy SourcesEconomic and technological development is linked with shifts in sources
of energy. The trend has been the adoption of higher
energy content sources, as the shift from coal (solid) to oil (liquid) and natural
gas (gas) indicates. This shift can be simplified into five major phases,
including one speculative about the future:
Up to the industrial revolution
(18th century), mankind's use of energy relied only on muscular
and biomass sources. Most work was provided by manual labor and
animals, while the biomass (mainly firewood) provided for heating and
cooking energy needs. Other sources of energy, such as windmills
and watermills, were present but their overall contribution was marginal
and very specific (e.g. milling flour).
By the mid 19th century, the industrial revolution brought a
major shift in energy sources with the usage of coal, mainly for
steam engines, but increasingly for power plants.
As the 20th century began, the major reliance was on coal, but
a gradual shift towards higher energy content sources like oil began.
This second major shift saw the introduction of internal combustion
engines and of oil-powered ships.
In the late 20th century, preeminence of petroleum products
as the main provider of energy reached a high level of
dependence in the world
economy. As its level of technical expertise increased,
more efficient sources of fossil fuels were tapped,
such as natural gas, and an entirely new form of energy, nuclear
fission, became available. Renewable sources of energy, such as
hydroelectric, wind and solar started to be tapped, but remained
marginal sources.
The 21st century will be characterized by major shifts in energy
sources with a gradual obsolescence of fossil fuels, like coal and
oil, for more efficient fossil fuels such as natural gas. There
may also be a substantial 'clean coal' technology potential (the
term is more of an oxymoron). Advances
in biotechnologies, underline the growing potential of biomass
derived fuels while wind and solar energy will also account for
a notable share of energy sources.
Nuclear energy, particularly if nuclear fusion becomes commercially
possible, may also play a significant role, but this remains
speculative. A new transition is likely to be the usage of hydrogen, mainly
for fuel cells powering vehicles, small energy generators and portable devices.
