PT X is building a $275$ km natural gas transmission line from Gresik to supply gas for power generation and industry in Semarang, Central Java with a capacity of $500$ mmscfd$.$ If the investment cost of the pipeline is $40,000$ US$$/$km$-$inch.

a$)$

Estimate the pipe diameter and total investment of the project!

b$)$

Also calculate the gas transmission cost in US$$/$mmbtu using the levelised cost method!

c$)$

Calculate the toll fee using the cash flow method: assuming a lifetime of $30$ years, interest rate loan $6\%,$ equity $=0\%($all from loan$),$ cash flow, interest rate loan $6\%,$ equity $=30\%,$ and use the rules of BPH$,$ compare the levelised cost and the estimated pipeline tariff from Seddon's book. Include other assumptions as needed!

d$)$

Calculate the ratio of cash flow to levelised cost.