# W8_TH_ Index and Power Sizing Technique for CNG Compressor Cost Estimating

##### 1. Problem Definition

Electric Motor has been choosing as a prime mover type for gas station project on Blog Week 3. In 2017, company will build new gas station project with capacity is 0.5 MMSCFD. Company has budgetary quotation data from three different compressor manufactures at 2015. Since the company will be using the price for calculate conceptual economic model, then the optimum price for 0.5 MMSCFD electric motor CNG compressor must be develop.

##### 2. Develop the Feasible Alternative

There are budgetary quotation price from three different compressor manufactures, as follow:

Table 1. Budgetary Quotation Price

##### 3. Develop of the Outcome for Alternative

Author will use formula of power sizing technique (correlation between price and capacity) and index to get cost estimation for 0.5 MMSCFD electric motor CNG compressor in 2017 project.

Fig 1. Power Sizing Model Formula

For index, author will use Chemical Engineering Plant Cost Index (CEPCI) because CEPCI is one of best bench-marking index since introduction in 1963.

Fig 2. Index Formula

Fig 3. CEPCI Index

##### 4. Selection Criteria

Author will use P50 at PERT analysis to determine optimum price for 0.5 MMSCFD electric motor CNG compressor.

##### 5. Analysis & Comparison of Alternative

Based on data and formulation above, here is the analysis and calculation for correlation exponent result:

Table 2. Correlation Exponent

Using correlation exponent (m), sizing model analysis for 0.5 MMSCFD for each budgetary quotation could be calculated as follow:

Table 3. Estimate Cost 0.5 MMSCFD CNG Compressor

The calculation above show still using 2015 database and to get reflection new cost 2017 the data shall be adjusted by CEPCI index value at March 2017 (Figure 3).

Table 4. CEPCI Index Value Result

##### 6. Selection of the Preferred Alternatives

Author use PERT analysis on P50 to determine optimum price, the result as follow:

Table 5. P50 PERT Analysis Result

Based on analysis above, price for 0.5 MMSCFD CNG compressor with electric motor prime mover is \$ 313,970.

##### 7. Performance Monitoring and The Post Evaluation Result

Power Sizing Model and Index Value above is a good formula to estimate the indicative price for conceptual economic calculation. It can be using of any kind project, such as oil & gas, automotive, power plant, etc.

References:

1. Planning Planet (2017). Creating The Owners Cost Estimate (Top Down). Retrieved from http://www.planningplanet.com/guild/gpccar/creating-the-owners-cost-estimate
2. Sullivan, G. W. (2014). Engineering Economy 16th Chapter 3 – Cost-Estimation Techniques, pp. 99-110
3. Irene, Audray. (2017). W5_AI_Power Sizing Model|Emerald AACE 2018. Retrieved from http://emeraldaace2017.com/2017/09/03/power-sizing-model-and-index-value-for-offshore-regasification-facility-project-cost-estimating/