Distribution of primary energy consumption by energy sources in 1999. Total Consumption: 92,5 PJ. Source: Barcelona Energy Improvement Plan (PMEB)

Primary energy is that which has not been subjected to any conversion process, such as solar or nuclear energy, energy generated by fossil fuel combustion, and wind, geo-thermal and nuclear-fusion energy.

If the generation of electricity is considered according to the mix found in Catalonia, it may be seen that nuclear power occupies first place as a primary energy source in Barcelona. The intensive use of fossil-fuel and nuclear energy is one of the main causes of the environmental deterioration or risk that may now be observed.