Page 239 - Materials Chemistry, Second Edition

228 R. Laleman et al.

Fig. 10 The impact of lifetime and irradiation on the FER a 3 kWp multi c-Si PV systems
(results based on calculations from Ecoinvent v2.0 compared with Cherubini et al. 2009)

5.2 Energy Efficiency of Electricity Production

5.2.1 Fossil Energy Requirement

The FER of 1 kWh of PV-produced electricity is lower than 1 in all the scenarios
(Fig. 10), which indicates that PV electricity is renewable. However, the results
are highly dependent on the assumed lifetime and irradiation. The FER in the most
pessimistic case, (20 years lifetime, installed in Belgium) is higher than 0.5 kWh/
kWhel. In the most optimistic case (30 years lifetime, installed in Spain), the FER
is about 0.2 kWh/kWhel. These results are on average slightly higher than those
found in Cherubini et al. (2009) but nevertheless comparable.
Note that the renewability of the electricity production of the country where the
PV cells and modules are produced also has a big impact on the FER since only
nonrenewable energy is incorporated. The FER would be very low, for example, if
the cells and modules were produced in Norway or high when produced in China.
The results from Ecoinvent represent a European case, with about 18 % of the
CED of a PV system being renewable. Recently, most PV panels sold in Europe
are produced in China, which would normally result in higher FER’s. It is,
however, unlikely that the FER for a kWh of PV-produced electricity would be
higher than 1, even in a pessimistic scenario.
Table 6 shows that, compared with wind and hydro, PV electricity production is
relatively energy intense. Biomass, on the other hand, has a FER similar to that of
PV. The fossil-fueled technologies are of course not renewable and thus have a
high FER (FER [ 1 for nonrenewables).
The FER’s for fossil technologies like coal and gas should be slightly higher
than the inverse of the efficiency of the power plant. For example, if a coal plant
has an efficiency of 35 % than the FER must be higher than 2.8 (2.8 = 1/0.35). 6
The FER will be slightly higher than this figure since other life-cycle energy

6
The efficiency of a plant indicates how much electricity (MJ el or kWh el ) is produced from a MJ
of primary energy, the energy contained in the fuel. The efficiency is thus a percentage with