by Dan Harmon – Project Manager, NAES Technical Services, with contributions from Operations Analyst Ralph Hecht

My job with NAES Engineering & Technical Services has yet again given me an experience I’ll never forget. Earlier this year, I traveled to the island of Sumatra in Indonesia along with Operations Analyst Ralph Hecht and CMMS Engineer Jesse Warby to continue work NAES had begun on a geothermal power facility being built by Sarulla Operations Ltd.

There is not a place on the globe that is more geographically opposite to Issaquah than Sumatra. Made up of approximately 18,000 islands that are home to over 300 million citizens, Indonesia is one of the most densely populated of nations. Sumatra, the largest of these islands, has one of the lowest densities. It lies on the Ring of Fire, a chain of volcanos and other geothermal features that dot the Pacific Ocean’s perimeter from New Zealand to Alaska to Chile.

As with most geothermal projects, the Sarulla developers started by locating a geothermally active cavity or aquifer that contains superheated, heavily mineralized water or ‘brine.’ They drilled a well into it, inserted a pipe and capped it, then poured concrete around its base to prevent leakage of steam.

Sarulla has incorporated the latest combined-cycle technology, so each unit will have a separator that removes the brine and then pipes the steam to the steam turbine. The brine is routed to a heat exchanger that heats a reservoir of ‘motive fluid’ – isopentane, in this case – which vaporizes at a lower temperature than the brine. The vaporized isopentane powers its own turbine, which substantially augments the steam turbine’s output.

Once the steam has driven its turbine, it cools, leaving a condensate that is then injected back into the geothermal well to replenish it, along with the separated brine that heated the isopentane to drive the secondary turbine.

Sarulla Geothermal Project makes up a core part of the Indonesian government’s electricity development program known as Fast Track II. Financed by the private sector, it also represents a growing trend toward privatization of utilities and other infrastructure. Anticipating the burgeoning electricity demands of northern Sumatra, Sarulla’s three-unit facility will provide 330 MW capacity, making it one of the largest geothermals in the world. Commercial operation of the first unit is scheduled to begin later this year, with the other two slated for 2017 and 2018 respectively.

Given Sumatra’s remote location and developing economy, we felt it was critical that we bring direction and clarity by providing Sarulla’s staff with a standardized set of operating processes and procedures. While it may not sound like much, it takes the guesswork out of many tasks that had so far been only vaguely sketched out for them. The work we did and continue to do as NAES technical experts greatly reduces the potential for safety incidents, environmental impacts and operating errors that could result in injury – or jeopardize what will be a baseload power supply on this electrically unstable island.

After flying into nearby Singapore, we decompressed for a day and prepared ourselves for the short commuter hop to Medan and eight-hour drive to Sarulla. Butar Butar, our good-natured and highly capable driver, seemed to dodge swarms of pedestrians, motorbikes and other cars effortlessly. Proud of his homeland, Butar took us to a coffee shop where we could sip the local ‘java’ and feed bananas to the monkeys that hang out along the banks of the world’s largest volcanic lake.

Besides making the island more electrically stable, we found it doubly satisfying to add value to a project in which the community took great pride. As an environmentally friendly power producer, the Sarulla plant plays its part in preserving the island’s natural beauty by adhering to strict environmental guidelines that we helped to refine.

We realized upon arriving at Sarulla that this was not your average tourist destination. In fact, much of Sumatra remains covered in undeveloped jungle – which I loved at first sight. Indonesia as a whole is home to some of the friendliest people we’ve ever met in the line of duty. Most of them spoke very little English but were eager to communicate in any way possible. The plant personnel took so much interest in us and our work that it was truly humbling, but this helped to streamline our efforts.

The Sarulla staff were also eager to show us what they knew, though it took some persuading to bring them around to the idea of doing things urgently. For instance, lunch was usually a three-hour affair. They greeted our requests to do walk-downs of the systems in the field with ‘after break time!’ Eventually, however, an eager entourage of a dozen employees would take us into the field. They clearly looked forward to having the policies and procedures in place and did their best to help us develop them. Even better, there were no egos involved, which made for strong collaboration and produced a better product.

One thing Ralph, Jesse and I shared was a pang of jealousy for the Indonesian way of life. The people we met seemed happy, relaxed and focused on the well-being of those around them. We saw children holding hands as they walked to school and adults waving to us as we drove by. Dinner seemed like a nightly party, as the Sarulla employees gathered at a restaurant in town to eat and sing karaoke.

Our work on behalf of NAES Technical Services will improve energy security and environmental stewardship for the people of Sumatra. Our programs and procedures will enable the Sarulla facility to operate safely and efficiently. The concepts we introduced to the staff were very foreign, as work is not generally done the same way it is here. But our work products have given the operators and maintenance technicians a sense of empowerment. They can now learn everything there is to know about a system, putting them on the same knowledge level as plant managers, which is a big deal there.

This work not only streamlined operations at Indonesia’s largest geothermal plant, it gave us a renewed sense of pride in NAES and the valuable work we do around the world as well as across the U. S. No matter where we go, everyone wants the same things – safety, environmental stewardship and efficient operation. It felt good to be able to deliver them to the people of Indonesia.