Kamojang (Part 02)

So, in previous part i had talked much about how do i end up with one of renewables energy sources: Geothermal. On this particular story i’m gonna tell you –my friends- about heavier topic of what i have done during my internship on PT. Pertamina Geothermal Energy (PGE).

PT. PGE has own the OLDEST geothermal plant in Indonesia (found on 1983). The company established on 2006 as a part of its mother company, PT. Pertamina Persero. On 2012 PT. PGE Kamojang had produced dry steam up to 12.339.808 407 tonnes and become one of an important source of electricity for Java-Bali distribution.

As i mentioned, i had given a task by my supervisor (Mr. Sidiq Nurbiyantoko) to sounding his result about the pressure drop from wellheads to suction of turbine on PT. PGE’s power plant. It was actually a simple quest which the only thing i should calculated is a ‘pressure drop’. By determining the pressure drop, then i should evaluate which wells should i put on the standby position and which wells should i keep to operates compare to the existing operation. Therefore, fluid mechanics will be the main key to solve the problem.

Still, it is have an interesting challenge. The wellheads are not lie on the same region/area where you can easily get the data by one spot at the time. Kamojang’s field was such a huge area of forest and each geothermal wellhead have a different ‘path’ to where it goes. Even in the same region, some wellheads could be ended up on different ‘finish-line’. Remember, PT. PGE is not only distirbutes dry steam to their own power plant. They were also exported them to the PT. Indonesia Power who also generate electrcity there. Furthermore, working field of PT. PGE are pretty much lies on the conversation field, that’s why although they had many wellheads to ‘mine-of’ but the wellshead could be faraway each other.

 Tiny little spots which looks like a swarm is actually the geothermal wells.

My methods to solve the problem is: First, taken a study about geothermal (it is an obvious thing right? :p) and also do a plant-observation. After that, I need to decide what is the main variables and equations are require for calcualting the presure drop to seek which and how many data that i should collected. Since the purpose is to decrease the number of operating wellheads for its sustainability. I had chose a ‘solver-analysis’ method from Microsoft Excel to help me execute the combination of the wellheads number, which one do i should put on standby position and which one do i should keep operates. Simply, the methods are given on the picture below. 

At the end of the result i found that the number of wellheads could be reduced until 8 wells to fulfilled the dry steam duty for suction head power plant’s turbine operation. Operating requirement of power plant’s turbine is the dry steam should be minimum on 430 tonnes/hour flowrate at 11.50 bar pressure. My recommendation result (8 wells) is the dry steam on 481.16 tonnes/hour flowrate with 11.70 bar pressure. In fact, number of wells which operates during my internship is 9 and produced approximately 511.29 tonnes/hour flowrate dry steam at 11.6 bar pressure. (continue)