Reducing the Energy Carbon Content - Energy and Climate: How to Achieve a Successful Energy Transition - page 67

6
Reducing the Energy Carbon
Content
The carbon content of the primary energy supply
The primary energy supply comprises all the energy sources which
contribute to the overall supply of primary energy: nuclear energy, coal,
oil, natural gas, hydroelectricity, biomass, wind, solar and geothermal
energy.
The diversification of energy sources is essential. It helps to reduce the
dependence on oil imports and thus to promote the security of supplies.
However, it is not necessarily beneficial in terms of climate change. Thus,
in the absence of appropriate measures, the comeback of coal might lead
to a significant increase in CO 2 emissions.
From this point of view, the situation can be improved only by
increasing the share of low carbon energy (nuclear and renewable), or
by using as energy vectors electricity or hydrogen produced from fossil
fuels with CO 2 capture and storage (see Chapter 8).
It is also possible to use biomass as an energy source. As the carbon
contained in biomass has been extracted from the atmosphere during the
photosynthesis process, it is considered as recycled when it is emitted as a
result of biomass combustion. The carbon balance of biomass combustion
is therefore carbon neutral (except if fossil energy has been used for
biomass production). A complete carbon balance has to take into account
all CO 2 emissions resulting from biomass production (agricultural ma-
chines, fertilisers, etc.), harvesting and transport to the final user site.