For the last several decades academic and NGO related environmentalists have pushed states and nations to reduce the size and number of their dams, often citing the ecological impacts dams have on fisheries, downstream agriculture, and on the broader environment.
With the adoption of the Kyoto Protocols many nations have looked to hydroelectric power as a key alternative to coal burning power plants. The common refrain has been that smaller dams are more culturally and ecologically friendly than large dams, like the Three Gorges project in China.
According to a study just released from OSU, while “the energy may be renewable, serious questions about whether or not the overall process is sustainable” remain.
According to associate professor Desiree Tullos, of the OSU Department of Biological and Ecological Engineering, small dams can cause, “damage to streams, fisheries, wildlife, threatened species and communities.”
Small dams on their own may not provide much power or do much damage, but when spread out over large areas they not only provide a significant amount of power, but open up environmentally sensitive areas to a significant amount of damage.
The five year study, which focused on the biologically sensitive and diverse province of Yunnan China, observed that, “fish, wildlife, water quality and riparian zones are all affected by water diversion, and changes in nearby land use and habitat fragmentation can lead to further species loss.”
When compared to traditional fuels, per megawatt of energy produced, “small tributary dams in some cases can have negative environmental impacts that are many times greater than large, main stem dams.”
One such environmental impact was described in another study, also from OSU, released in 2010. In that study researchers noted that, “Methane emissions due to decomposing organic material in some reservoirs may offset a portion of GHG saved by hydropower production.”
The researchers also noted that, with small dams, there was less oversight and governance concerning the construction, operation, maintenance and monitoring of small hydropower installations. Like with franchise businesses, quality control is not always up to snuff in smaller installations.
While big dam projects may appear to cause more environmental damage, the potential for smaller dams, when widely spread, to cause systemic damage cannot be overlooked. In humanity’s quest to find alternative sources of energy to power our ever growing electrical appetite, nations must balance the costs as well as the environmental and cultural impacts against the threats of future climate change.
By William Tatum