The Ulu Padas Hydroelectric Project in Sabah, Malaysia, has been validated as a low-carbon reservoir using the G-Res Tool, a greenhouse gas (GHG) assessment framework developed by the International Hydropower Association and researchers at Université du Québec à Montréal (UQAM).
According to project developer Gamuda Berhad, the reservoir recorded emissions of 19.9 grams of carbon dioxide equivalent per kilowatt-hour (gCO₂e/kWh). This is significantly below the commonly referenced global threshold of 100 gCO₂e/kWh used in the hydropower sector to distinguish low-emission projects.
The G-Res Tool is a peer-reviewed, science-based model used to estimate net GHG emissions from freshwater reservoirs. It evaluates emissions from sources including carbon dioxide and methane, taking into account factors such as reservoir size, depth, climate conditions, and pre-existing land use. The tool reports emissions intensity relative to electricity generation, allowing comparison with other energy sources.
The methodology has been adopted across the hydropower industry and is aligned with the Hydropower Sustainability Standard, which provides guidelines for environmental and social performance. Industry bodies including the Hydropower Sustainability Alliance promote its use to improve transparency and comparability of hydropower emissions data.
Hydropower reservoirs can emit greenhouse gases, particularly methane, due to the decomposition of organic matter in flooded areas. Emissions vary widely depending on design and location. Studies associated with the G-Res framework indicate that deeper reservoirs in tropical regions can reduce methane release by limiting the breakdown of vegetation in oxygen-poor conditions near the surface.
The Ulu Padas project is planned as a large-scale hydroelectric development on the Padas River in Sabah’s interior and is expected to have an installed capacity of around 187 MW. The scheme includes a dam, reservoir, power intake and underground or surface powerhouse, along with associated transmission infrastructure to connect generation to the regional grid. The project is being developed to support growing electricity demand in Sabah and to strengthen grid stability, particularly by providing firm, dispatchable renewable power to complement variable energy sources.
Gamuda said the Ulu Padas project incorporates design measures aimed at reducing emissions, including a deep reservoir configuration, vegetation clearing prior to inundation, and planned replanting programmes. These measures are intended to minimise organic decomposition and support longer-term ecosystem management.
The project is being developed in partnership with local stakeholders including Sabah Energy Corporation and is part of broader efforts to expand renewable energy capacity in Malaysia. Hydropower remains a key component of the country’s energy mix, particularly in East Malaysia, where large-scale river systems offer development potential.
