Naoro Brown hydroelectric project

Client: PNG Power Ltd
Location: Port Moresby, Papua New Guinea
Date: January 2010 – March 2015

Investigating hydropower generation options and power system modelling to supply more renewable energy to PNG’s capital city, displacing costly diesel generation.


Port Moresby is Papua New Guinea’s largest city and has a growing need for reliable and cost-effective power. PNG Power Ltd plans to develop the Naoro Brown hydroelectric project, to add up to 80 MW of much-needed new renewable generation capacity to the Port Moresby power grid, reducing the need for expensive diesel generation.


PNG Power turned to Entura to conduct feasibility studies for the Naoro Brown Project, including detailed site investigations associated with survey, hydrological assessment and geotechnical drilling.  A power system study, which modelled the Port Moresby generation and transmission system in detail, assessed any modifications required to successfully connect this new generation into Port Moresby’s transmission system, taking into account options, fault contribution, spinning reserve and reactive power requirements.

Entura prepared a full feasibility study, including a summary of the investigations undertaken, assessment of alternative options, preliminary design of the project, energy assessment based on a simple storage model, project implementation schedule, cost estimation and project economic analysis.

The final preliminary design consisted of a 20m dam to provide 11 Mm3 of live storage for flexibility of operation, 10.35 km x 4.25m diameter headrace tunnel, a surge shaft and 1.71km of power tunnel to a surface power station housing 4 x 20MW Pelton turbines.


Entura presented a cost-effective hydropower project that could be safely and reliably integrated. Based on our extensive hydropower experience, we identified key risks for the project, and guided PNG Power on where best to spend additional funds on further investigations prior to final commitment to the project.


A key risk to the project was potential seepage through the right abutment of the dam due to various lava flows and vesicular basalt. As a result, Entura specified additional investigations at the Naoro Brown dam site, including a grouting trial of the highly permeable vesicular basalt and investigations of the cut-off required on the right abutment of the dam. In addition to this, some further geological drilling and testing was specified along the headrace tunnel to inform the tunnel risks, including support systems and lining requirements. Entura supervised these additional investigations and updated the feasibility study based on these findings.

Through World Bank Financial support, PNG Power engaged a transactional advisor in 2016 to investigate, define and execute the optimal competitive tendering process for procurement of a private developer. In addition to this, a consultant was engaged to undertake a detailed Social and Environmental Impact Assessment.