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The G-res Tool is a simple-to-use, web-based tool that can be used to predict GHG emissions from reservoirs without going to the field to take measurements.

The tool is designed to help hydropower companies and researchers estimate and report the net greenhouse gas emissions of a reservoir. Reporting results gained using the G-res Tool give investors, regulators and local communities greater confidence on a reservoir’s climate profile and carbon footprint.

A decade in development, the tool was created through a multi-stakeholder research project led by the International Hydropower Association and the UNESCO Chair in Global Environmental Change. The G-res Tool was developed using a conceptual framework created with scientists from the University of Quebec at Montreal (UQAM), the Norwegian Foundation for Scientific and Industrial Research (SINTEF) and the Natural Resources Institute of Finland (LUKE), with assistance from the World Bank.


Natural emissions

All ecosystems, including river systems, naturally emit greenhouse gases such as carbon dioxide and methane.

When a reservoir is created, there will be a change in GHG emissions which are dependent on local environmental conditions.


Net emissions

Greenhouse gases can be released when a reservoir is introduced due to the decomposition of organic material in the flooded area.

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Assess, Validate, Report and Model


Web-based tool

The G-res Tool uses readily available input data to estimate the change in emissions resulting from the impoundment of an existing or planned reservoir.

The free online tool takes into account emissions related to human activities and infrastructure and allocates these to various reservoir purposes.


Quality of results

Validation acts as an approval stamp attesting the quality and rigour of the use of the tool and represents an independent verification of the results produced.

This process is mandatory to publish any G-res Tool results in official documents and reports.

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The tool allows companies and researchers to report publicly the estimated net greenhouse gas emissions caused by the creation of a reservoir.

The assessment framework uses a methodology based on empirical measurements from more than 200 reservoirs worldwide.

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Reliable and cost-effective

Hydropower, when planned and designed correctly, is regarded to be among the lowest-carbon sources of renewable electricity generation.

Before now, however, there was no reliable and cost-effective way of estimating the emissions created from building a reservoir, taking into account pre-existing conditions and naturally occurring emissions.

Upcoming training dates

G-res Tool July Training

This training will take place virtually between 23 – 26 July 2024. Participants are expected to join live sessions on 23, 25 and 26 July at 09:00-13:00 Brisbane time.

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We offer training courses to help individuals and organisations use and accurately interpret results.

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Services and support

Our team can provide assisted assessments and validate G-res Tool results for reliable and transparent reporting.

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"The development of the G-res Tool is a major milestone in the research on GHG from reservoirs. This is the first scientifically based tool for planners and designers to quantify reservoir emissions.”

– The World Bank

"Another innovative feature of the G-res Tool is its ability to calculate the net impact of a future reservoir on the GHG regime of a particular site. This is a significant breakthrough.”

– Yves Prairie, UNESCO Chair in Global Environmental Change

"As a consultant, I can see growing demand for GHG emissions estimates in tenders for hydropower projects globally. Thanks to the training I received on the G-res Tool, I can now provide clients with cost-effective GHG emissions analyses as a certified user.”

– Karin Grandin, Sweco

"The G-res Tool helps non-scientists to easily measure a reservoir’s carbon emissions. With ongoing improvements to suit different climate regions, the tool provides a convenient approach for hydropower operators and companies, such as Sarawak Energy, to estimate the greenhouse gas profile of a reservoir.”

– Jenny Choo, Sarawak Energy
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