How The World Can Meet Climate And Energy Targets, While Keeping Its Remaining Free-Flowing Rivers
The International Hydropower Association (IHA) is concluding its biannual World Hydropower Congress this week. During the Congress, IHA released several statements and reports, including: (1) a report, Hydro 2050, that calls for increased investment in hydropower to achieve a doubling of global capacity by 2050; and (2) the San Jose Declaration, which strongly asserts that all future hydropower development must be sustainable by implementing rigorous, globally recognized standards.
The Congress was planned to be held live in Costa Rica before moving virtual due to the pandemic – hence the geographic name of the Declaration.
These two visions presented at the Congress—all future hydropower must be sustainable on the way to doubling global capacity—are likely not compatible.
Ironically, the intended location of the Congress, Costa Rica, provides a strong counterpoint of a vision that is more sustainable: power systems that are low carbon, low cost and low conflict with communities, rivers and other natural resources.
Costa Rica has long depended on hydropower to meet the majority of its electricity demands (about 65 – 75% of its annual generation). Costa Rica is also a leader in recognizing the economic value of forests, coral reefs, rivers and other natural assets. Last decade, those foundational resources came into conflict with each other.
A hydropower dam was proposed on the free-flowing Térraba River, the longest river fully in Costa Rica. Conflict about the dam’s impacts led to a modified proposal for the El Diquis Dam to be built on a tributary to the Térraba. That dam’s reservoir would have inundated land belonging to the Teribe people and displaced several villages. Further, changes to the river’s flow and sediment supply would have negatively impacted the 30,000-hectare Térraba-Sierpe National Wetlands downstream, an important area for Costa Rica’s ecotourism sector.
Following protests and legal action by the Teribe people, the government of Costa Rica decided to permanently suspend El Diquis dam in 2018. Beyond the conflict, the government asserted that, due to successful energy efficiency efforts and changing costs of generation options, El Diquis was no longer consistent with least-cost expansion of the power system. The government has pledged to become carbon neutral within the next few years and its power system expansion plans to 2034 do not include additional hydropower, with growth focused on solar, wind and geothermal resources. The country’s existing hydropower projects will play a key role in balancing the increased proportion of variable generation sources.
Costa Rica’s power system is simultaneously low carbon, low cost, and, going forward, striving for low conflict. The country’s grid is currently 98% renewable with a carbon intensity of 54 gCO2 per kWh (about one-tenth that of the United States), with consumer cost essentially equal to that in the United States. With its recent decision to protect rivers and the rights of indigenous people, future expansion of Costa Rica’s power system will avoid many of the conflicts caused by the damming of free-flowing rivers.
IHA’s San Jose Declaration also emphasizes sustainability, stating that “the only acceptable hydropower is sustainable hydropower.” However, the simultaneous call to action for a global doubling of hydropower capacity will be nearly impossible to reconcile with that pledge, as long as the values of free-flowing rivers are included within a definition of sustainability.
The approximate doubling of global hydropower in IHA’s Hydro 2050 is based in part on recent reports from the International Renewable Energy Agency (IRENA) and the International Energy Agency (IEA), which concluded that meeting climate targets will require a near doubling (IRENA), or doubling (IEA), of current global hydropower capacity. IHA indicates the higher doubling value will be necessary to reach the 1.5° C climate target. However, none of the three reports indicate where the doubling will occur (i.e., which rivers will be dammed).
A research paper released in August provides some insight on where this doubling would occur (note, I was a co-author on the paper). This paper used the only publicly available global database on planned future hydropower expansion to model potential impacts on rivers. This database includes just over 700 GW of potential future hydropower, so somewhat less than the 850 GW proposed in Hydro 2050 and approximately half of the additional hydropower called for in the IEA report.
This smaller increment of new hydropower would fragment 260,000 kilometers of currently free-flowing rivers. The potential impacts of such development can perhaps be more clearly understood by focusing on large tropical rivers (>1000 km in length). These rivers support the highest number of aquatic species and also the greatest values to people, including much of the harvest of freshwater fisheries, the primary source of protein for hundreds of millions of people. These rivers also carry sediment that creates and maintains deltas—home to 500 million people and some of the most productive agriculture on the planet (about 4% of all food production on just 0.5% of the earth’s surface).
Human activity has already fragmented half of the world’s large tropical rivers, with past hydropower development being the leading cause. The study found that if the proposed hydropower dams are built, about half of the remaining free-flowing large tropical rivers will become fragmented, resulting in globally significant negative impacts to deltas (and the hundreds of millions of people that live on them), fisheries (and the hundreds of millions of people that depend on them) and aquatic biodiversity.
And what would be gained in exchange for these dramatic tradeoffs? Less than 2% of the renewable electricity generation needed by 2050 to meet climate targets (212 GW of the 700 GW are proposed on free-flowing rivers).
This level of impact occurs when modeling the addition of 700 GW. Meanwhile, IEA and IHA are proposing twice that scale of hydropower development, without specifying where the expansion would go or how it could happen without resulting in a world where nearly 80% of its large rivers are no longer free flowing.
However, there are models and studies that suggest that the world can achieve the 1.5° C climate target without requiring such a steep tradeoff. Sven Teske of the Sydney Technology University led development of a global scenario that meets that climate target, and this scenario included a lower expansion of hydropower, 300 GW, by 2050. A 2019 study by WWF and The Nature Conservancy (led by me) modeled the potential impacts on rivers from developing 300 GW of new hydropower. We found that the lower level of hydropower expansion, with careful planning and siting, could reduce impacts on rivers by 90%, relative to impacts from building 700 GW of new hydropower
Diverse groups are converging on a consensus position that we must accelerate the transition to decarbonized economies – and avoid and minimize impacts on communities and nature while doing so. There is considerable common ground for collaborative progress. For example, IHA’s Hydro 2050 highlights the significant opportunity to increase global generation from hydropower by retrofitting and modernizing existing hydropower projects, with a potential increase in generation between 10 and 30%. In the United States, the hydropower sector, dam safety organizations and conservation organizations are working together to promote legislation that would fund the retrofitting of existing hydropower dams to improve their safety, environmental performance and ability to support wind and solar—and also remove thousands of aging dams to restore free-flowing rivers. A team from the Australian National University suggests that well-sited pumped storage hydropower could provide much of the needed storage and grid balancing services for power systems with generation dominated by solar PV (IHA also focused on pumped storage in its Congress).
Again, Costa Rica is instructive. Existing hydropower will be essential to the nation’s pursuit of low conflict and low carbon power system expansion. Within Costa Rica, 7 of its 11 rivers longer than 100 kilometers remain free flowing (64%, compared to an average of 43% of such rivers that remain free-flowing in the United States and the European Union). When confronted with the social and environmental conflicts of damming its biggest remaining free-flowing river—with what would have become Central America’s largest hydropower project—the government of Costa Rica pulled back. A growing appreciation for the tradeoffs of damming free-flowing rivers, combined with the fruits of the renewable revolution—including dramatically dropping costs—led the country to announce that future grid expansion will instead emphasize wind, solar and geothermal.
The San Jose Declaration includes important commitments to sustainability, but the future called for in Hydro 2050 will make those commitments extremely difficult to achieve. However, another set of decisions made in San Jose over the past decade may illuminate a pathway toward power systems that are both low carbon and low conflict.