Cost sensitivity studies

Cost sensitivity studies have shown that the successful commercialization of cellulase-based processes, such as the conversion of cellulose to fermentable sugars, is highly dependent on the cost of enzyme production (i). Because fungal -D-glucosidase (EC 3.2.1.21) is the most labile enzyme in this system under process conditions (2), and k to efficient saccharification of cellulose, this enzyme was targeted for application of stabilization technology, both through chemical modification and immobilization to solid supports. 

Cost Whether measurement or a computation technique is cheaper depends on the situation in question. In small and simple problems, it is usually more profitable to use measurement techniques. In large and complex problems, where parametric/sensitivity study is the objective, computation may be a better alternative. 

Sensitivity studies have shown that costs are likely to be contaminant specific and depend on plant size and location. The design of a commercial facility has not been finalized. Solar collectors are the largest cost component of solar detoxification systems, and some research indicates that a one-sun system (in a one-sun system, solar energy is not concentrated by reflectors or solar panels) that does not use a solar collector may be more efficient in accessing diffuse ultraviolet light. Another design concern that may impact process costs is the use of a fixed catalyst versus a slurry feed (D12953N, pp.190-203). 

Coating and membrane costs sensitivities have been studied (Figure 3) in cases of coating thickness or cost doubling (resp. membrane cost doubling). As a result, the installed electrolysers cost increases up to 20% (resp. 24%). 

Technical sensitivity studies, in which some critical process parameters are varied to study their effects on the overall performance or cost. 

The choice of which feed and product prices to use in the sensitivity analysis depends strongly on the method of price forecasting that has been used. Typically, total raw material cost is studied rather than treating each feed separately, but if raw material costs are found to be the dominant factor, then they may be broken out into the costs of individual raw materials. 

An alternative route for the conversion of natural gas to liquid fuels, which employs acetylene rather than the more conventional synthesis gas intermediate, was studied to identify some of the engineering problems and cost-sensitive areas of processing. The limitations of this route as a model for other alternative processes are discussed. 

An economic analysis generally involves more imcertain-ties than a thermodynamic analysis. In the above discussion, it has been assumed that each variable in the eco-norrric analysis is known with certainty. However, many values used in the calcirlation are uncertain. A sensitivity artalysis determines by how much a reasonable range of uncertainty assiuned for each uncertain variable affects the frrral decision. Sensitivity studies are recommended to irrvestigate the effect of major assmnptions about values referring to future years (e.g., cost of money, inflation rate, and escalation rate of fuels) on the results of an economic analysis. 

S. A1 Obaidani, E. Curcio, F. Macedonio, G. Di Profio, H. Al-Hinai, and E. Drioli, Potential of membrane distillation in seawater desalination Thermal efficiency, sensitivity study and cost estimation, J. Membr. Set 323 (2008) 85-98. 

It is also possible to have the ROI (during the third operating year) estimated and to carry out sensitivity studies. This is accomplished by pressing the Choose Custom Analyses button, which produces the Custom Analyses dialog box, and checking the ROI (Third Year) entry. In addition, the IRR can be computed as a function of a single variable or as a function of two variables. These variables are the product price, variable cost, fixed cost, initial investment, and the rate of inflation. 

In contrast, in more cost-sensitive applications where AMFCs may find their first commercial employment, non-precious N-M-C catalysts are expected to become the material of choice, though considerable maturation of these as of yet unproved materials is required before such a scenario could become a reality. The majority of recently described catalysts are either less active than Pt, less durable than Pt, or both. The very best N-M-C catalysts appear thus far to have advantages over Pt in both activity and durability, but the preliminary results on these materials come from half-cell studies in liquid electrolytes considerable effort will be required to adapt these materials to AMFC electrodes. Such efforts are complicated by the immature state of AMFC membrane and electrode ionomer technology, both of which lag behind catalyst development. The lack of widespread availability of high-performance membranes and ionomers to catalyst developers has limited MEA testing to date, but such testing is required to confirm the activity and durability of alkaline ORR catalysts in the AMFC environment. 

Step 6. Perform sensitivity studies. It is useful to know which parameters in an optimization problem are the most important in determining the optimum. By varying model and cost parameters individually and recalculating the optimum, the most sensitive parameters can be identified. 

The RELAP5/MOD3 code is based on a non-homogeneous and non-equilibrium model for the two-phase system that is solved by a fast, partially implicit numerical scheme to permit economical calculation of system transients. The objective of the RELAP5 development effort from the outset was to produce a code that included important first-order effects necessary for accurate prediction of system transients but that was sufficiently simple and cost effective so that parametric or sensitivity studies were possible. 

Simulated Annealing-based solutions [19] are conceptually the same as Genetic Algorithm-based approaches. However, the SA-based techniques, in our experience, are more sensitive to the initial settings of the parameters. Nevertheless, once the correct ones are found, the method can achieve the efficiency of GA-based solutions. We must point out that SA-based solutions have never outperformed the GA-based ones in our studies. Much of what has been mentioned regarding the GA-based solutions is also relevant for the SA technique, particularly, with respect to the cost functions. 

Sensitivity Analysis An economic study should pinpoint the areas most susceptible to change. It is easier to predict expenses than either sales or profits. Fairly accurate estimates of capital costs and processing costs can be made. However, for the most part, errors in these estimates have a correspondingly smaller effecl than changes in sales price, sales volume, and the costs of raw materials and distribution. 

A further detail of this study included sensitivity analysis for the area of heat exchangers, discount rate, and fuel cost. The results are listed in Table 3-8. Option 2, the turboexpander scheme, was selected in terms of energy and maintenance savings, as well as enhanced reliability, availability, and safety. 

The impact of loss of tax credits, loss carry forward, and other tax benefits should be studied. Such things as start-up problems that increase the first year s operating costs and reduce the production should also be studied. With a good economic computer program, such as described earlier, all of these sensitivity analyses can be made in an afternoon. 

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