Best Paper: Stirling engine, electricity equalization solution in Papua

The Minister of National Development Planning / Head of Bappenas Bambang Brodjonegoro gave an award to Isna Riski Safira at the Indonesia Development Forum 2018

Survey of the Ministry of Energy and Mineral Resources in June 2017 showed that Papua's electricity coverage ratio only reached 48.74%. This figure shows that Papua is still far behind compared to other regions that have an average ratio of 92.8%.

Papua Province has 3,761 villages that have not been supplied by electricity, with a population of 4,247,758 people as of June 2017. If the electricity coverage ratio is 48.74% and the assumption of one household consists of 4 people, there are 2,177,400 people (544,350 households) who are not provided with electricity. The total capacity of power that needs to be installed is 180 MW for eastern Indonesia, assuming that electricity consumption will be about 0.6 kWh /household per day.

In the effort to meet the electricity needs, the government has planned the development of 2015-2019 electricity supply infrastructure for Maluku and Papua. The target is to build 43 power plants with a capacity of 739 MW within this year and next year. To achieve the development plan, various types of alternative power plant development are explored by the government.

On May 19 2017, the Ministry of Villages, Development of Disadvantaged Regions and Transmigration made a memorandum of understanding regarding the coordination of the preparation for the development of renewable energy power plants in Papua Province. This MoU contains plans to build a solar power plant, a grant from Winrock International because solar power is considered the solution for future renewable energy development. Until the end of 2017, the construction of 70 MWatt MHP in Nabire and Jayapura had been completed.

Unfortunately, besides being expensive, the use of the Solar Power Plant is not really effective. The reason is because the lights only illuminate, do not supply electricity which can be used for sewing or other productive activities .

However, the implementation of the Gas Engine Power Plant raises a new challenge because distributing liquid fuel is still very difficult to do. Papua has a very large area with low population density. People do not live close to one another and geographical and topographic condition are challenging. In addition, Papua also has a problem in infrastructure to distribute logistics which is in this case is fuel. So, to improve the efficiency of meeting electricity energy needs in Papua, an alternative power generation system is needed.

Isna Riski Safira, a student of the Bandung Institute of Technology, explained that power generation solutions that use new and renewable fuels, can utilize the potential of surrounding resources, with minimum need to do equipment maintenance. The idea of ​​using a Stirling Machine with a capacity of 200 Watts to overcome the electricity needs in Papua, made Isna won the Best Paper in the Indonesia Development Forum 2018.

Stirling Machine and Biomass Potential in Papua 

The Stirling engine is a machine that works based on a closed cycle, where liquid fuel is compressed on a cold cylinder volume and expanded on a hot cylinder volume. The design of the stirling machine is most suitable for an area like Papua  since it has a long between maintenance-interval due to the minor movement it will make, and it is also effecient.

To answer the challenge of meeting the efficient electrical energy, the small Stirling Machine measuring 30 x 30 x 15 cm as in the Thermodynamics lab of FTMD ITB offers more advantages compared to those of piston engines. This machine has an advantage  in terms of the flexibility in fuel use. It is also not too noisy, and has a relatively long operating life of up to 10,000 hours with minimum maintenance because oil is not contaminated by combustion or foreign particles so that the engine, and combustion occurs outside the engine making emissions control easier to do.

The sterling machine can also use biomass as fuel. Papua itself has renewable energy potential including biomass. Papua Province has a biomass potential of 81.4 Megawatts while West Papua has 50.8 MW. The types of biomass that are widely distributed in Papua are palm oil production residues and plywood and coating wood production. The area of ​​oil palm plantations in Papua reaches 958,024 Ha.

Although this island has abundant biomass potential, unfortunately there is no on-grid biomass power plant. Meanwhile the off-grid power plant biomass power is only  from palm oil which produces power of 4 MW. This is because there is no government plan to build a biomass power plant yet.  

Capital Building to Procure Machines

The total number Stirling Machines needed in Papua is around 544,350 units with a capacity of to produce 200 Watts for each machine. This figure is obtained from the number of households that have not been supplied by electricity.  Cost calculations are carried out in two stages, namely the calculation of prototyping and the calculation of mass production. The calculation of prototype making has been carried out through direct observation by the production site, while the calculations for mass production are carried out analytically using references in G. Boothroyd (1994).

The cost of making prototypes includes the purchase of production tools, the cost of using production machinery, and the purchase of raw materials. The manufacturing value is Rp. 32,500,000. If the purchase cost of the production tool is taken out of the calculation because it can be used more than once, the unit cost is only around Rp. 16,000,000.00

When mass produced, the cost needed to produce one machine is Rp1,000,000. This price is quite reasonable considering there will be also other costs such as the cost of shipping machines between islands and other costs which have not been included in the calculation.

The price of the electricity generation of this machine reaches Rp. 359 / kWh when using LPG gas fuel and Rp. 239 / kWh when using palm oil fuel. This fee looks very cheap because it only considers the cost of making the machines added up with fuel costs to simplify calculations. As a comparison, cost for energy produced by a Micro-hydro Power Plant is around Rp. 736 / kWh taking into account similar cost elements.

The use of oil palm is the best in terms of price for Papua. These costs include the purchase of 1 ton of palm  amounting to Rp. 700,000.00 on average. One kilogram of Palm will burn out within 7 minutes. So, to turn on as many as 544,350   Stirling Machines for 166 days 34 tons of palm shells are needed, equivalent to a fuel tariff of Rp. 6,000 per hour. This cost is much cheaper than using LPG which costs Rp. 25 thousand per hour. **