Martina Schäfer, Noara Kebir, Daniel Philipp (editors) - TU Berlin

PROCEEDINGS Conference MPDES 2011
However, overall, gasification outperformed wind and
anaerobic digestion on the social criterion. This is due
mainly to higher socio-economic benefits from job
creation. Anaerobic digestion has the least overall ranking
in social criterion. This use of human and animal wastes
for biogas production and the subsequent digested sludge
as a source of fertiliser faces cultural and health resistant
from the community. On the environmental sustainability,
wind technology suffers from visual impact (aesthetic).
However, some of the stakeholders argued that wind
technology executed with thoughtfulness, will blend in
seamlessly with its surroundings and could be viewed as a
sculptural element of the landscape. It was generally
accepted that wind technologies are better neighbours than
traditional energy sources and provide power generation
with zero to low carbon emissions. On the impact on birds
and terrestrial ecosystem, the impact from wind
technology is very small compared to buildings,
communication towers and transmission towers. Today’s
tubular tower design gives no reason for birds to be
attracted for nesting as the older scaffold design had been.
Proper siting of the technology is however the most
important aspect to reduce risk to birds and terrestrial
ecosystem. Sites should be studied to determine the
migratory and local avian patterns for sustainable
development. The largest barrier for PV’s extensive
utilization is its high cost. Despite the fact the cost has
decreased over the years as newer technologies and
advancements dictates a more economic viability for
broader use, the overall cost is still unaffordable for most
of the Eastern Cape rural communities.
A head-to-head comparison between photovoltaic and
wind, shown in Figure 4, revealed that wind technology is
both environmentally and economically more sustainable
than photovoltaic.
Photovoltaic on the other hand is more socially and
technically sustainable than wind. From the social
sustainability point of view, some of the concerns raised
by the community include opportunities for local
employment arising from the manufacture, installation
and operation due to the specialised knowledge or
equipment required for wind technology and the fact that
wind prospecting is still in its infancy in South Africa.
The technical sustainability which entails using best
practice products, services, work practices and
institutional arrangements, as well as the fostering of
appropriate innovation in hardware, software and
institutional framework, with an appropriate balance of
self-sufficiency objectives at local, regional and national
levels favours the application of photovoltaic technology.
This is primarily due to the locally available technology
and experience with this technology. South Africa has
over 20 years experience in the manufacture and
distribution of PV systems. The bulk of the companies
produce Balance of System (BOS) component for use as
electrical controls and power storage device (GTZ, 2010).
However, the mean price of electricity generated from PV
is higher than wind technology.
A head-to-head comparison between photovoltaic and
anaerobic digestion is illustrated in Figure 5. The Figure
revealed that photovoltaic is socially, environmentally and
technically more sustainable, while anaerobic digestion is
more economically sustainable. A central feature of both
biogas and photovoltaic technology is that almost all
expenses need to be financed upfront, with very low
operating expenses thereafter (Amigun and von Blottnitz,
2007). This is problematic where poverty is endemic.
Anaerobic digestion is economically sustainable
compared to photovoltaic because the technology is
constructed with locally available materials such as
cement, stones, and a mixture of quicklime, sand and clay
and no industrially advanced materials.
A sensitivity analysis was carried out to explore the
stability of the alternative priority structure. Specifically,
the aim was to explore the sensitivity of decision-making
processes to simultaneous variations of the preference
parameters. The consequence of these preferential
uncertainties on the results of the analysis could then be
ascertained. Figure 6 show the overall performance scores
of the alternatives when the weight of the criterion under
consideration is varied from 0 to 1. The vertical axis in
Figure 6 represents the overall value of the alternatives
and the horizontal axis represents the variation scale of the
weight-from zero to one- for each criterion. The point
where an alternative line intersects such a vertical line, as
read from the axis on the right (labelled Alt%) indicates
the priority the alternative received on that criterion.
The overall priority of each alternative is where it
intersects the rightmost axis. It was found that the overall
ranking of PV solar was the highest when the weight of
the social criterion was changed from the initial 25% to
46% while, keeping the proportions among the remaining
weights unchanged. This is followed by wind, gasification
and lastly anaerobic digestion technology. When the
weight of the technical criterion was changed to 93% from
the initial 25%, wind technology moves to the second
position and photovoltaic becomes the preferred
electricity generation technology option. A change in the
weight of the environmental criterion to 46% will only
make gasification technology the third preferred
technology after wind and solar PV. The change in weight
to 100% does not have any significant impact on the
ranking of the wind and solar PV technologies. Economic
criterion has a significant impact on the order of
technology ranking. Increasing the weight from the initial
25% to 31% will push anaerobic digestion to the second
place after wind technology. At 33% increase, PV solar
was the least ranking after wind, anaerobic digestion and
gasification. The sensitivity analysis indicated that
economic criterion has the highest impact, followed by
social criterion.
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