Reducing the Energy Carbon Content - Energy and Climate: How to Achieve a Successful Energy Transition - page 82

(competition with food uses, consumption of water, fertilisers and
pesticides).
If we restrict ourselves to the current first generation processes, com-
petition with food uses appears when the incorporated rate in fuels
exceeds 5-10%. The new processes, whose production is based on
lignocellulosic biomass, must therefore be implemented to reach higher
penetration levels.
Care must be taken in this case to ensure that the biomass is produced
under conditions acceptable for the environment and, in particular, does
not result in deforestation or irreversible soil degradation.
Improvement of the CO 2 balance, a critical selection criterion, must
be assessed by performing a complete analysis of the life cycle, from
the biomass production step through to use of the biofuel in the
engine. It is absolutely essential to perform this life cycle analysis, since
some cereal-based ethanol production processes, requiring large quan-
tities of fossil energies to convert the biomass, offer little or even zero
benefit.
In contrast, the more recent lignocellulosic biomass conversion path-
ways currently being explored reduce the global CO 2 emissions by
70-90% over the entire biofuel production and utilisation cycle.
Emissions of greenhouse gases other than CO 2 , in particular nitrous
oxide (N 2 O), resulting from the use of nitrogen-containing fertilisers,
must also be taken into account.
In order to achieve high penetration rates of more than 10%, while
respecting sustainable development criteria and without compromising
the production of biomass for food use, new biofuel production processes
based on lignocellulosic biomass must be developed.
These criteria must always be respected, no matter which process is
implemented. This is an essential condition if biofuels are to make a
significant contribution to solving energy and climate change problems.
The role of hydrogen
Apart from the special case of biomass, renewable energies can only be
used in the form of electricity (wind, photovoltaic) or possibly low-
thermal-level heat (thermal solar and geothermal).
Energy diversification will therefore involve first increasing the use of
electricity (in particular through heat pumps) and, secondly, introducing
an energy vector which can serve as fuel and supply high-thermal-level
heat, especially for industrial applications, without emitting CO 2 .