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232 R. Laleman et al.

technologies. The emissions from a coal plant are about 10 times higher. Emis-
sions from gas are roughly 5 times higher. It is also interesting to note that CCS
(Carbon Capture and Storage) technology will only reduce emissions down to
about 200 gCO 2 -eq/kWh, which is about twice the average of PV emissions
(Jaramillo et al. 2007; Viebahn et al. 2007; Weisser 2007). This is food for thought
given the increasing interest in CCS technology to reach climate goals.
PV thus seems to have relatively low GHG emissions. However, compared with
other renewables, wind and hydro are better options. Especially, wind technology
seems to have very low per kWh GHG emissions from a life-cycle perspective
(Martinez et al. 2009a; Martinez et al. 2009b; Varun et al. 2009a).
Nuclear also has a relatively low GHG impact, since almost no emissions occur
during the process of nuclear fission. Also, one nuclear plant can produce a lot of
electricity, thus the emissions released during construction are divided over a huge
number of kWh’s, resulting in a low per kWh greenhouse gas impact. On the other
hand, the advantage of nuclear with regard to GHG emissions is overshadowed by
the big debate on its safety. Nuclear appeared to be an option to fight climate
change a few years ago, however, since the Fukushima accident the political
feasibility of nuclear had decreased dramatically.
The GHG emissions related to biomass electricity production are in the same
range as PV, according to most of the literature. Biomass is, however, a special
case, since a lot of the emissions can be attributed to the harvesting and transport
phases. Lowering GHG emissions in these steps is thus crucial to obtain a low-
carbon energy source. Many factors influence the overall GHG-balance of a kWh
of biomass electricity. Land use change, for example, can significantly contribute
to the overall emissions, be it in a positive (carbon capture and soil improvement)
or very negative way (such as the burning of rainforest to replace it with biomass
plantations) (IPCC 2011). The big influence of the assumed land-use impact partly
explains the large variations in emissions that can be found in the literature. In the
papers mentioned here, the emissions vary from 2 to 150 gCO 2 -eq/kWh. The
variation reported by the IPCC (IPCC 2011) is even larger, ranging from -600
gCO 2 -eq/kWh up to +300 gCO 2 -eq/kWh, depending on which assumptions and
methods were applied. These figures suggest that the debate on the sustainability
of biomass for electricity production is not likely to end soon.

5.4 Eco-Indicator 99 Analysis of 1 kWh of Electricity

5.4.1 Comparing Different Perspectives

The results that were found using the EI 99 method for a residential 3 kWp PV
system in Sect. 3.4.2 varied greatly depending on the selected perspective.
Figure 12 shows that this observation remains valid for the comparison of different
energy technologies. In order to simplify the results, only the three main impact
categories (resource depletion, human health, and ecosystem quality) are shown.