Publications

March 2026              by Open Hydro              White paper

Freshwater reservoirs play a complex and often overlooked role in climate mitigation and adaptation. While they can emit greenhouse gases such as CO₂ and methane, they may also act as carbon sinks under certain conditions. Open Hydro’s Water IMPACT Project, funded by Innovate UK, developed the first Earth Observation–driven machine learning model capable of predicting reservoir CO₂ and CH₄ fluxes at individual asset level and over time.

Applied to 476 UK reservoirs, the research reveals that emissions are highly dynamic and strongly influenced by seasonal conditions, water quality, and catchment processes. The findings challenge the assumption that reservoirs are always net emitters and show that some can function as net carbon sinks. By enabling scalable, explainable emissions estimates, the approach provides water utilities with a new tool to improve greenhouse gas inventories, identify reservoirs with sequestration potential, and prioritise interventions that deliver both water quality and climate benefits

Hydropower secures only 2.5% of climate-aligned finance even though it is the largest renewable energy generator. Open Hydro’s guideline tackles this with the first industry-specific guidance to improve reporting towards investors in hydropower. It was co-developed with hydropower experts from 10 top electric utilities and financial institutions and reviewed by the Task Force on Climate-related Disclosures (TCFD), the GHG Protocol and the World Benchmarking Alliance.
It is the first of its kind and much needed in the hydropower industry. It gives hydropower operators a framework by which they can report their emissions that have been created specifically for the industry. Frameworks for carbon accounting have already been published. Still, they are not specific to hydropower, which is more complex due to geography, age, construction materials, sediment flow and many more individual factors to each hydropower asset.

After five years of the Paris Agreement, UN Secretary-General António Guterres called on leaders to declare a State of Climate Emergency until reaching carbon neutrality. The Intergovernmental Panel on Climate Change (IPCC) states global emissions must be halved by 2030 and reach net zero by 2050 to avoid climate catastrophe.

This white paper analyses the trends around climate risk disclosure worldwide, covering the challenges and opportunities for hydropower. It studies and compares TCFD recommendations with international taxonomies and finds an emerging need for standardised metrics and industry-specific reporting standards. It also presents the insights gained from a survey to understand the impacts of climate resilience and adaptation reporting to unlock climate finance for hydropower assets. To conclude, it suggests ways forward for downscaling commonly-agreed climate-related reporting to the hydropower-specific project level.

With the G7 agreeing to implement mandatory disclosure aligned with TCFD recommendations, these are turning from a voluntary approach to the main regulatory response to disclose climate-related risks and opportunities. Given the upcoming mandatory requirements, the hydropower sector needs to prepare as 513 GW of hydropower capacity is potentially subject to mandatory climate-related disclosure.

However, with 198 GW, electric utilities supporting TCFD recommendations represent only 15% of the hydropower installed capacity worldwide, reaching 1,330 GW in 2020. Still, they represent over 40% of the hydropower installed capacity in Europe. To assist the hydropower sector with specific recommendations and standardised metrics to ensure the information is relevant and valuable for financial decision-making, Open Hydro is leading to streamlining climate reporting.