Hydropower’s capacity to reduce carbon emissions to help meet net zero goals was highlighted by the Intergovernmental Panel on Climate Change (IPCC) earlier this month in the third and final instalment of their sixth assessment report on climate change, writes IHA Energy Policy Manager Rebecca Ellis.

Hydropower is mentioned frequently throughout the report from Working Group III (Mitigation of Climate Change), as a means to mitigate the worst impacts of climate change, and especially in chapter six on energy systems.

The report says with high confidence that established technologies like hydropower form one of the many technologies available to reduce emissions over the next decade. It also notes that the peak efficiency of hydroelectric plants is greater than 85 percent.

Hydropower is a cost-effective path to net zero

The report focuses on mitigation and specifically what activities we must do now to limit warming to 1.5°C or well below 2°C. The authors indicate that mitigation pathways limiting warming to 1.5°C must reduce CO2 emissions by 50 percent in the 2030s, relative to 2019, then reach net zero CO2 emissions in the 2050s.

Importantly, it states with high confidence that the levelised cost of electricity (LCOE) for hydropower is lower than the cheapest new fossil fuel-fired option, and that hydropower is one of the lowest-cost electricity technologies. For a lifetime of 40-80 years for a hydropower project, the costs for operation and maintenance were found to be ~2-2.5 percent of the investment costs per kw yr-1.

In addition to the lower investment costs over its lifetime compared with cheap fossil fuels, the potential for hydropower is massive and exceeds total electricity produced in 2018. While not all of this will be developed, the report recognised that hydropower makes up a substantial part of renewable energy providing 16 percent of global electricity and 43 percent of electricity from renewables for 2019. The summary for policymakers included a bar chart that shows the relative potential for hydropower is still high even in 2030. And even more interesting to note, is that public support for hydropower is generally high, and correlates to existing projects having high support; whereas, according to the research, new projects have less public support.

The only acceptable hydropower is sustainable

As hydropower often requires significant land use, the report says (in chapter’s six and 12) that it is critical to minimise environmental and social impacts during planning stages, to reduce potential risks. It is also necessary to modernise the existing fleet to increase generation capacity and flexibility. As such, it is important to mitigate risks that may impact ecological habitats, and to consider “local physical, environmental, climatological, social, economic, and political aspects”. To mitigate such risks and impacts, the International Hydropower Association (IHA) recommends that all hydropower projects be built using the Hydropower Sustainability Standard.

The Standard provides a framework to ensure that social and environmental impacts are considered, and that any hydropower project proceeds in a just and equitable manner, in line with the report. The report details, in chapter 17, the importance of focusing on distributional climate justice to ensure the transition be sustainable and just. The authors of that chapter conclude that “accelerating climate actions and progress towards a just transition is essential to reducing climate risks and addressing sustainable development priorities, including water, food and human security”.

While the previous instalment of the IPCC report, from Working Group II (Adaptation and Resilience), noted that climate change will alter hydropower production, and especially at the regional scale, the impacts are uncertain. Working Group III’s report concludes that the analysis consistently demonstrates that the global impact of climate change on hydropower will be small, and while regional impacts will be larger, it will be both positive and negative.

Hydropower’s flexibility and storage services are critical

In addition to recognising the significance of hydropower for its role in climate mitigation, pumped storage hydropower and reservoir storage were also noted for their ability to provide flexibility services to compensate for rapid variations in electricity loads and supplies. The report noted with a high degree of confidence that energy storage will play an increasingly important role in net zero systems, especially those with high variable renewable energy shares, and that dispatchable renewable generation (such as hydropower) will provide critical support for net zero.

In addition to the policy role of government, the latest IPCC report indicated that there is an immense gap between how much capital is available and what is needed. It is noted with high confidence that “fundamental inequities in access to finance as well as its terms and conditions, and countries exposure to physical impacts of climate change overall result in a worsening outlook for a global just transition”.  

IHA as the voice of sustainable hydropower knows the importance of the role that hydropower has played and will continue to play in meeting net zero goals. United Nations Secretary General Antonio Guterres’ said of this month’s report: “It is time to stop burning our planet and start investing in the abundant renewable energy all around us. The new IPCC report sets out viable, financially sound options in every sector that can keep the possibility of limiting global warming to 1.5°C alive”.

Hydropower is a necessary part of a net zero future and must be prioritised in national and global plans for the clean energy transition.

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