In order to properly analyze hydropower, both on a theoretical and practical scale, developing a basic understanding of its implications is necessary. Hydro’s physical infrastructures, potential benefits, ramifications, and broader climate interactions, although seemingly disjointed from the core focus of this thesis, are critical in gaining insight to social resistance motivations and strategies presented further on. Additionally, the common portrayal of hydropower as a “renewable” energy will become relevant as I explore political economic contexts. Although there are far more factors involved than I present here, the discussion below serves as a basis in displaying the complexity and depth of consideration hydro development necessitates.
Global Presence
Large and small-scale river development is now routine worldwide. By 2011, there were approximately 37,600 dams higher than fifteen meters on earth (International Commission on Large Dams 2011). This does not account for the thousands of small-scale and run-of-river projects. Figure 1. displays the 3,700 new major hydro projects, more than one megawatt production capacity, which were either in the planning or construction phase as of 2014 (Zarfl 2014). As global energy demand is anticipated to rise from 2014 – 2040 by 56%, such an intense hydropower development era does not seem likely to slow.
Figure 1. The distribution of planned and currently being constructed hydropower projects as of 2014, not including small-scale or run-of-river developments (Zarfl 2014).
Infrastructure
Hydro projects utilizing surface water most prominently include dam based reservoir systems or run-of-river (ROR) tunneling systems, both of which use gravitational forces to instill and then harness water’s kinetic energy. For either of these systems, developers target rivers based on factors such as temporal flow patterns, surrounding topography and geology, relative location of urban centers, and potential megawatt (MW) capacity. The MW production capacity of a hydro project is generally dependent on the volume of water moving through the system, and also the elevation difference between the system’s inflow and outflow.
Hydropower reservoir systems[1] store large capacities of water behind river wide dams. Generally, these dams have an intake opening which runs water through a penstock and then rotates a turbine that is connected to a generator. The energy produced by the generator, converted within a powerhouse, is then transported though a system of power lines and towers, which require road infrastructure. Water exits the system though an outflow channel, which can also consist of constructed spillways to decrease erosion potential.
Most commonly, ROR systems[2] function by siphoning a river’s water out of the bed through an intake infrastructure, which generates little to no storage. The water then runs through a tube system, potentially tunneled underground, and then enters a turbine/powerhouse generation system at a lower elevation (Haddad 2011). The water is released from the system downstream of the original collection zone. Like reservoir systems, ROR requires similar power transportation infrastructure and road development.
Benefits
The overarching goals of hydropower are to generate clean, low cost, renewable energy, in addition to other project specific benefits. For example, hydro can theoretically produce a constant flow of energy depending on basin conditions and the type of generation system used. Reservoir hydro is also able to match energy demand fluctuations, increasing or decreasing stored water use. As hydro harnesses kinetic energy, minimal emissions are produced during operation. Additionally, once a catchment, production, and transportation system is constructed, either reservoir or ROR, operating costs are virtually non existent (Prieto 2012). Beyond energy production, reservoir storage can also be used for irrigation purposes, inland water transport, or flood mitigation, on a range of scales (Ansar 2014). ROR developments, although unable to store mass quantities of water, can potentially produce constant energy while maintaining a river’s flow regime.
Ramifications
While all forms of energy production and transportation infrastructures have various ramifications, due to the amalgamating nature of river basins, hydro development impacts also expand throughout the networks in which they are constructed. Whether a project’s ramifications outweigh its benefits is dependent on many case specific factors, and is ideally judged considering long-term ecological and social prosperity through impartial analysis. Analysis must further account for uncertainty of ecological limits of hydrologic alterations (ELOHA). While calculable in some regards through the use of modeling and analysis of individual river characteristics, ELOHAs are less predictable due to “the confounding of hydrologic alteration with other important environmental determinants of river ecosystem condition” (Poff 2010, 2).
Through river fragmentation, both dam and ROR systems impact flow dependent ecosystems (Bunn 2002). Reservoirs specifically alter both upstream and downstream temperature averages by generating a relatively stagnant and deep pool in the reservoir, and allowing downstream release generally of one temperature regime through the penstock. Sediment accumulation behind a dam not only creates lateral pressure upon the structure, but lends itself to eutrophication due to a halting of nutrient and pollutant transport downstream combined with potentially increased surface temperatures (Grant 2003). Reservoirs also generate deforestation of the previously terrestrial land their water covers. Release of methane occurs due to decaying organic material in the newly anaerobic environment (Maeck 2013). Among numerous other impacts, reservoir filling can force or block species migrations generating ripple effects upon both flora and fauna (Avakyan 2002). Failure risk is also a possibility that must be considered and monitored effectively (Hartfort 2011). While ROR systems do not generate large reservoirs, they have the ability to siphon great portions or the majority of a rivers’ water is away from its course. Depending on how much flow is utilized, the dewatering of a river section alters sediment transportation, temperature gradients, and other habitat health requirements (Fassnacht 2003). Complete fragmentation of these components is possible if the majority of flow is siphoned. Fish populations, for example, must adapt to often halted or degraded migration pathways in either reservoir or ROR systems. Furthermore, a significant flow regime alteration facilitates more successful invasions of exotic species (Bunn 2002). When considering these examples in addition to the hydraulic uncertainties, alteration impacts to river flow regimes are clear and thus must be fully contrasted against potential benefits.
Depending on scale, hydro projects can be physically intrusive and economically burdening. The infrastructure required to generate and transport hydropower can become destructive, especially when accessing more remote areas. For example, roads must be built large enough to move equipment and materials for construction. Additionally, transmission lines and towers needed to connect to a main energy line add to impacts such as deforestation, habitat intrusion, and visual pollution. While actual operation costs are low, construction costs and potential mitigation and damage repair issues can amount to extraordinary financial burden, especially with large developments. As large sums of money are involved, “optimistic judgments” or justifications for a hydro project “are often exacerbated by deception, i.e. strategic misrepresentation by project promoters” (Ansar 2014, 7). Among management authorities, the reality of profit margins has often promoted an acquired ignorance of not only realistic MW estimations, but also ecological consequences.
All of these impacts vary based on river flow volume, broader basin dynamics, type and size of hydro development constructed, and other anticipated and unpredictable factors. Political flow negotiations, both domestic and transnational, are a prevalent dilemma for both management systems and water users dependent on allocation decisions. As smaller basins often feed into larger systems, treaties and compacts regarding downstream flow requirements, especially in transboundary basins, become more complex when hydro production is an added dynamic. While neutrality is necessary in considering hydro development dynamics, it is undebatable that “hydrologic alteration has impaired riverine ecosystems on a global scale, and the pace and intensity of human development greatly exceeds the ability of scientists to assess the effects on a river-by-river basis” (Poff 2010, 1). This is not to condemn the form of energy, as it has the potential to be used in a locally beneficial and ecologically responsible manner, but rather to take an all encompassing perspective when considering basin alterations.
Interaction with Climate Variation
Increasing climate variations are also straining water management systems. Mitigating current and future concerns from such variation, including drought patterns, is further complicated for systems that are already navigating river development impacts. While the implications of climate variations differ for every basin, general patterns[3] can be heightened in instances where basin self regulation has already been compromised by fragmentation. These patterns and “altered water cycles…clearly affect the safe and economical operation of dams and reservoirs” (Schleiss 2011, xiii). While some management systems have made efforts to adapt to less predictable flows and overall basin alterations,[4] many have not sufficiently reacted to diverging hydrological patterns. Climate change has thus created a new platform for ecological and social instability when considering hydro developments, in addition to economic and political concerns over decreases in reliable energy production.
“Renewable” Energy Portrayal
Hydropower has been promoted by general political standards of “renewable” and “sustainable” energy. Although geothermal, solar, wind, tidal, and biomass energies are portrayed in a similar way,[5] hydro accounts for the majority of the world’s “renewable” energy production. Hydro continues to be included in many countries’ energy plans as the main or even sole source of “clean” power. This reliance has clarified that the “mastery of nature may be effective in the short-term in generating rising consumption patters, but also in masking the long-term implications of ecosystem stress” (McMichael 2011, 11). While the use of water’s kinetic energy is renewable in terms of the general hydraulic cycle, climate variations and the compounding nature of basin degradation due to flow fragmentation brings into question the reality of hydropower’s “renewable” portrayal. This label is further jeopardized when considering political and economic motivations, which will be discussed later. While there are intricacies beyond the factors emphasized above, this analysis of implications and impacts presents a logic as to why many human communities question, and in many instances resist, hydropower development.
[1] For more details and diagrams, please see (Perlman 2015).
[2] For infrastructure specifics and a diagram, please see (SmallHydro 2009).
[3] Many basins dependent on snowpack melt have experienced seasonal abnormalities. Due to warmer average temperatures, precipitation in winter months moves through the system earlier or evaporates more quickly than historically anticipated. Increasingly arid landscapes are emitting more dust which mixes with snowpack and amplifies solar heat attraction, melting snow more rapidly (EPA 2015).
[4] To ensure that both Mexico and the U.S. would have long-term access to the Colorado basin’s water, Minutes 242 and 319 were incorporated in 1973 and 2012 respectively. 319 not only recognized the impacts of climate change and redefined the amount of water Mexico receives based on upstream reservoir levels, but also adapted allocations to improve the ecological health of the Colorado River (IBWC 2012).
[5] Please reference (Aden 2010), in the context of China, and (Goel 2009) for comparisons of these energies against each other and conventional sources.