Global reliance on hydroelectric energy production has only increased in the 21st century, even as our supply of hydropower has become increasingly uncertain due to climate change impacts, including glacial retreat. South Asia is a clear example: due to the high cost and political risks of importing fuels like oil or coal, countries in this region have increasingly turned to hydroelectric power for domestic energy production. But changes to the Himalayan hydro-ecosystem could severely disrupt future hydroelectric development in South Asia.
Today, large regional electrical grids feed most global energy demand. To maintain constant supply and meet demand as efficiently as possible, different “tiers” of power plants tend to work together. “Base load” power plants, such as nuclear and coal generators, are most efficient when providing a constant supply of energy around the clock, as opposed to in short bursts to meet peak demand, and so form the backbone of most electric grids. “Load following” power plants are used to adapt to short-term changes in demand, typically shutting down at night or early morning. Examples include natural gas or diesel and renewable power plants. “Peaking power” plants can start and stop very quickly but are far less efficient than base load plants at longer timescales and are more expensive to run than load following plants. They typically come online for only a few hours a day to meet peaks in energy demand. Diesel and gasoline internal combustion engines are examples.
Hydroelectric generators can theoretically be used to fill any of these roles, depending upon the availability of water, the size of the reservoir, and the installed capacity. For this reason variations in hydro-ecosystems have a large impact on the energy potential available to such generators. If a hydroelectric plant is supplying base load energy, low stream flow can lead to power outages. If such a plant is used to supply peak needs, declines in water supplies at the wrong times can cause voltage drops or brownouts. Conversely, if the reservoir is too full due to heavy rain or snowmelt, spillways have to be opened and the energy often cannot be used at all. For these reasons hydroelectric plants are most commonly used as load following plants. Some even pump water back up river into reservoirs as a form of energy storage if production is high when demand is low.
In the Himalayas, hydropower is at grave risk, and yet there is virtually no supplementary base load power available, and little ability to purchase energy from other sources. As Himalayan glaciers melt at unprecedented rates, springtime stream flows have become more intense and unpredictable, while the risks of glacial lake outburst floods and landslides are growing. The severe inconsistency of the water supply could even cause hydroelectric projects to fail, flooding downstream communities. Ultimately, investments in hydroelectric power in the region may be disproportionate to the amount of energy that these plants will realistically be able to produce, given the ecosystem risks.
Although South Asia is in a notably precarious position, such concerns are not uniquely Himalayan. In fact, according to a study by Schaefli et al., the net effect of global warming in Switzerland will be to noticeably reduce hydroelectric production, which is a serious problem for a country where 75% of electricity comes from hydroelectric power. Another 2014 study on Swiss hydropower by Ludovic Gaudard et al. has warned that increased water scarcity may lead to competition for water uses, further limiting water available for energy production. As such, the country has been taking measures to insure energy resilience, managing its hydro projects more closely and investing in other forms of renewable energy. According to the results of a project by the Swiss Sustainable Water Management National Research Programme, more careful water management practices could make up for increasing stream flow uncertainty.
In the US Pacific Northwest, scientists are advocating for greater attention to the ways in which climate uncertainty will affect their energy resources. Matthew S. Markoff and Alison C. Cullen find in a recent study that the region’s energy grid will be impacted by global warming as soon as 2020. According to the EPA, on the American Colorado River, a 1% reduction in stream flow from climate change can reduce electricity output from the various hydroelectric plants that run along it by as much as 3%. And in California, a report from the Department of Water Resources states that:
“Climate change will reduce the reliability of California’s hydroelectricity operations . . . changes in the timing of inflows to reservoirs may exceed generation capacity, forcing water releases over spillways and resulting in lost opportunities to generate hydropower. Higher snow elevations, decreased snowpack, and earlier melting may result in less water available for clean power generation during hot summer months. . .”
The report goes on to outline management, policy and funding measures that should be taken to prepare for this reality. Many of these measures are similar to the measures outlined in the Swiss and Pacific Northwest reports.
In each case, the recommended measures are relatively nonspecific, however: increased attention to the uncertainty, and the implementation of increased security standards to protect communities from severe floods and sediment build up. Safety standards can be more easily addressed through the reinforcement of reservoirs, damns and levees, to prepare them for more sporadic and intense stream flows. To address uncertainty, the reports recommend preparing to adapt, and increasing the availability of other forms of renewable energy.
As the world faces widespread glacial retreat and growing climate uncertainty, it is becoming imperative for public and regulatory agencies to take into consideration how climate change will affect energy resources and public safety. This is especially true considering that hydroelectric power is currently the world’s largest source of renewable energy, and that sources of nonrenewable energy are depleting. As the industrialized world publishes studies, drafts plans, and prepares to deal with these risks, industrializing nations like those in South Asia do not always have the same flexibility. Moving forward, different regions of the world must work together to assure the safety of dams and reservoirs, the resiliency of electrical grids, and the sustainability of energy supply.