The Essential Energy Transition - Energy and Climate: How to Achieve a Successful Energy Transition - page 46

More generally, the energy transition requires the implementation of
hybrid systems combining several forms of energy, different fuels and
propulsion modes, in order to progressively increase the proportion of
non-fossil energy in the energy mix.
Flexible systems, which can operate on different forms of energy,
simplify the transition by allowing the user to opt for an alternative
energy without having to make an irreversible choice from the outset.
Flex-fuel vehicles (FFV) which can run on gasoline, ethanol (E85), or any
mixture of the two, are one example. Vehicles equipped with dual fuel
engines, that can either run on liquid oil fuel or on LPGor NGV, represent
another example of transition technology.
The energy storage systems must become more efficient and more cost-
effective. Fossil fuels store a large amount of energy in a limited volume
and can therefore be stored very easily, especially in vehicles. This is not
the case with most alternative energy sources which must be converted
into electricity (nuclear, wind power, photovoltaic solar power, etc.).
Greater recourse to the renewable energies due, for most of them
(apart from ex-biomass and geothermal energy), to their intermittent
nature, will imply a need for energy storage systems.
Increased deployment of energy vectors compatible with the use of
different energy sources also represents one way of facilitating the
transition. Greater reliance on electricity will therefore tend to favour
diversification of energy sources. Eventually, the use of hydrogen as an
energy vector may play a similar role and help extend the number of
applications potentially concerned.
In the future, the energy system will rely on extended interconnected
energy networks, offering more flexibility than the current electricity
networks, and on efficient energy storage systems.
Decentralised electricity production systems could connect to networks
like this, with the prospect of a progressive growth in renewable energies,
in particular wind and photovoltaic power.

A global transition

The transition to be made is not related to energy alone, it must be much
more global. The other transitions to be implemented concern in particular:

. Demography

. The world population has exploded from 3 billion
inhabitants in 1960 to 6.5 billion inhabitants in 2005. The growth