OOSKAnews Voices: Feeling the Power of Climate Change: What Is Green Hydropower in a Shifting Climate?

CORVALLIS, OR, United States

OOSKAnews Voices is a new series of guest “opinion columns” on water, written by senior participants in different parts of the international water community. The columns provide a global platform for organizations and individuals to promulgate their views and messages.

In this piece, John H. Matthews, co-founder and secretariat coordinator for the Alliance for Global Water Adaptation (AGWA), which is chaired by the Stockholm International Water Institute (SIWI) and the World Bank, delves into the controversy over how "green" hydrolectric power really is.


Matthews’ work integrates technical and policy knowledge for climate adaptation for practical implementation. John has worked globally on these issues since 2007 and has authored many publications on adaptive management for water infrastructure and ecosystems. He has a PhD in ecology from the University of Texas and is based in the United States.

The opinions expressed in this article represent the views of John Matthews, and are not endorsed by OOSKAnews Inc.

While reviewing comments on climate finance standards from a variety of actors -- NGOs, development banks, commercial investors -- I have been struck by the extreme positions around hydropower. Is it possible for hydropower to be credibly considered “green?” Should we promote hydropower as a sustainable option, at least in regard to climate change? Evidence, opinion, and interest collide in discussions about hydropower sustainability.

Perhaps more than any other water-related topic, hydropower represents some of the most extreme risks and opportunities associated with climate change policy and practice. In terms of slowing the speed of climate change for future generations while also meeting growing energy demands, it is critical to pursue low-carbon energy. For many middle- and low-income countries, hydropower is generally seen by policymakers as the single most viable option available. From Nepal and Bhutan to Turkey, Ethiopia, and Peru, intensive hydropower development promises less extreme global warming and long-term energy security.

Hydropower has long been a mainstay of the most developed economies. The first commercial-scale hydropower generation facility was located on the US-Canadian border in the 1880s, and the so-called “golden era” of dam-building in western Europe and North America that spanned roughly 1925 to 1965 was in many ways a “big hydropower” period. As a result, both North America and Europe have exploited roughly 70 percent of their hydropower potential -- we literally would have difficulty finding locations for large new facilities, and the energy sector has become one of the most important consumers of water resources in these regions.

How many facilities have been built is a matter of controversy, especially once we begin to include the full range from micro and pico units to massive installations such as the Three Gorges and the Hoover dams. The quantity of stored water has detectably altered the rate of the rotation of the earth by altering the planetary moment of inertia, while more recent reports suggest that the sea-level rise has been slowed in part because of continental water storage.

The confluence of increasing energy generation capacity and rapid 20th century economic growth has not been lost on the developing world. A recent paper in Science by Winemiller and colleagues suggests that at least 450 additional large hydropower dams are planned for the Congo, Amazon, and Mekong basins alone, while another study suggests that Vietnam alone plans to install over 200 new facilities between 2012 and 2017. Africa has made use of only about one-tenth of its hydropower potential. We may have entered the "platinum era" of dam building.

While reducing the rate of climate change is certainly not the sole justification for these trends, low-carbon climate mitigation finance is helping to fuel additional development. However, the net carbon benefits may not be that well understood for hydropower, especially with storage reservoirs, and the evidence base is relatively weak for understanding how methane emissions from the tropics to the temperate zones may be increased. Little in the way of long-term monitoring data appears to be available, although a meta-analysis of isolated studies could reveal more insights. Hydropower is probably a dirtier form of clean energy than many policymakers realize, but exactly how dirty does not seem clear (at least to me) from the available evidence.

Studies on the environmental impact of different hydropower dam types are less mixed. Opinions vary wildly about the relative impact on large vs small (or micro) facilities and run-of-the-river vs reservoir storage systems (often with little evidence for assertions that smaller and particular designs are “better”), but in general the evidence from older facilities suggests that the impacts on sediment flow, fisheries, and other ecosystems are sudden and strong and difficult to mitigate, especially for poor designs after construction has begun.

I live in a region of North America whose forests have been nourished for millennia by ocean nitrogen as a result of massive salmon migrations; these migrations have been severely attenuated by mid-century dam construction. The complex linkages between aquatic, marine, and terrestrial ecosystems are exceptionally difficult to maintain with built infrastructure. Current structural approaches tend to address ecological concerns late in the development process, when greener solutions may be difficult or prohibitively expensive to implement. As John Briscoe and others have argued, the need to alleviate poverty often translates into infrastructure -- especially new infrastructure -- and usually new energy infrastructure.

These now-old critiques are currently being driven by new concerns about climate change impacts: What happens when the assumptions made about the timing and quantity of water for a given facility are no longer valid? Given that the first commercial hydropower facility is still in operation after 125 years, the longevity of even small installations will span climate-relevant timescales for (at least) many decades. For countries such as Norway, Peru, and Bhutan, hydropower is the overwhelming source of energy. Are they vulnerable to reduced capacity?

The wrinkles and creases of ongoing climate change are already evident on many older facilities, while only a handful of genuinely useful efforts have been put forward for designing robust structures that are sustainable in terms of their energy generation. Most of these efforts are only at the exploratory or pilot stage, while my sense is that the long-term risks for new facilities are not even being explored in the overwhelming majority of cases.

We do not yet have good examples of resilient hydropower. A future with increasingly widespread climate-infrastructure mismatches means a world with tense and troubled allocation and governance, less energy security, and possibly more difficult environmental tradeoffs.

As a biologist who also cares deeply about poverty alleviation and economic development, I believe we need hydropower for a slower rate of climate change and less poverty. But even the greenest solutions we have today may not deliver the full measure of their promise -- green for now may not be green for tomorrow.

A valued and thoughtful colleague at a think tank summarized our large set of comments by saying, “We must first decide if hydropower is in or out of the sustainability discussion, and if it is in, then how we can distinguish between good and bad. And I am glad I do not have to make the final decision.”