Multiple objective models provide decision support to decision makers by providing a tool for rationalising the comparison among alternative solutions, thereby enabling the decision maker to grasp the inherent tradeoffs and conflicts among the distinct objectives and thereby selecting a satisfactory compromise (Antunes et al; 2001). It is further argued by Heinrich et al (2006) that multiple objective models provide a structured framework for the evaluation of various parameters that are non linear (e.g environmental and social) as well as elements of uncertainty over a period of time. Both authors highlight the applicability of such models to electricity planning. Any move towards a sustainable solution should be driven by a rational argument directly related to the problem as well as the democratic desire to change (Lafferty, 1998).
of decisions through the involvement of full knowledge of the system in question (Muller, 1992) the decision to include FGD at the time of construction or at a later date would require the generation of a series of alternative scenarios and solutions all of which will need to be evaluated against a single set of objectives.
Pirasashti (2009) argues that the evaluation of a solution derived from a multi criteria problem can only be accepted if the following conditions are met, namely: that selection criteria are aligned to corporate strategy, that qualitative (rather than just quantitative) benefits are considered; that the needs and desires of all stakeholders are reconciled and integrated and finally that multi staged and group decision making processes are used. Simply put the decision whether or not to install FGD at Medupi cannot be considered in isolation of all other decisions, it needs to be taken within the context of all contributing internal and external factors
The aim of multi criteria decision making is to allow decision makers to learn about the specific problems which they may face, to learn about personal value systems, to learn about organisational values and ultimately through the exploration of all of the above within the context of the problem to identify a satisfactory solution (Pirasashti et al, 2009). The methodology allows for the identification and ranking of alternatives on the basis of several criteria (Climaco, 1995). In multi criteria models the concept of the optimal solution or the nondominated solution is the most feasible solution for which there is no improvement in any objective function without sacrificing on at least one of the objectives (Climaco, 1995).
Several methods exist for the identification of the non dominated or preferred solution, one approach involves the analysis of trade-offs against a common objective, such as cost. By assigning cost benefits or penalties to each of the more significant non cost criteria. Alternatively it is possible to recast all except one objective functions as a set of constraints operating on the remaining objective function. Finally a third option, and in the opinion of the author, potentially a favourable option within a large parastatal environment, is the evaluation of the objectives separately through the use of weighted sums of each. Such a method allows for interactive participation with all stakeholders in the definition of the weights and the goals until a satisfactory solution is reached (Heinrich et al, 2007). Such a methodology allows for lobbying and co-operative buy in to be gained at an early
A key aspect of multi criteria decision making is its ability to manage uncertainty. Sinding (1998) states that the minimisation of uncertainty within an organisation is a critical objective as it affects corporate strategy and economic efficiency.
1.6.1. Managing uncertainty
With reference to FGD in the context of environmental problem solving, such as the case of including FGD on Medupi, uncertainty is derived from both internal and external sources. External uncertainty includes the ambiguity about the natural environment and the various cause and effect relationships that exist (Sinding, 1998), with specific reference to FGD and associated air quality this can also be extended to human health issues. In addition regulatory responses are also considered to contribute to external uncertainties particularly as a result of the fact that environmental regulation is continually changing moreover policy instruments used by government are also continuously been reviewed and amended (Sinding, 1998). Finally Sinding (1998) states that the third area of external uncertainty is derived from external responses relating to actions that an organisation may take as a result of some external influence.
With respect to internal sources of environmental uncertainty Sinding (1998) identifies three areas of specific impacts namely, financial; organisational values and information processing impacts.
Perhaps the most important question that arises is how does multi criteria decision making take uncertainties into account. Heinrich et al. (2007) state that the consideration of uncertainties in multi criteria decision making involves the concepts of ‘robustness’ and ‘flexibility’ of the solutions generated. In this context robustness is defined as the degree to which a solution is affected by any parameter which at the time of its development was unknown. Similarly, flexibility is defined as the degree to which a solution can be adapted at a future point.
From the above discussions it is evident that multi criteria decision making provides a means for the choosing and or ranking of alternative scenarios on the basis of the evaluation against several, often weighted, criteria or objectives. It is therefore plausible that any decision making process with respect to the sustainability of installing FGD at Medupi would require the identification of a range of environmental, social and economic criteria which could be used to evaluate the two scenarios that
construction or make the necessary engineering decisions to allow for FGD to be retrofitted at a later stage, with the least amount of effort and cost
It is at this point that the focus of this research report is reached. Although acknowledging that the identification of criteria will span across a range of sectors including cost, electricity planning, technology decision making and so forth, this research report will solely focus on the identification of the environmental criteria within the sustainability debate. Inter-relationships will be identified and discussed where appropriate, but for the most part environmental concerns will be addressed with a specific focus on the external environmental factors contributing to the uncertainties of any multi criteria decision model.
Furthermore, it is acknowledged that the potential scenarios do extend beyond the two identified above and will include FGD technology choices and configurations, however for the purposes of this report the two identified scenarios will be considered with respect to wet FGD.
Finally, it should be noted that no attempt will be made to under take any multi criteria analysis rather only , within the scope identified above, the decision making criteria will be identified, with appropriate discussion, motivation a criticism, which may be utilised within a suitable decision making model.
1.7. Objectives
The purpose of this research report is to generate (via modelling) as well as collate/identify various environmental criteria and considerations required to evaluate the impacts of either installing wet FGD, at Medupi Power Station at the time of construction or alternatively install FGD at a later time period.
It is not within the scope of this research report to comprehensively explore all possible alternatives and objectives as well as to draw a final conclusion through the use of multi criteria decision making.