The Irony of Hydropower

Photo from Wikipedia

Hydropower is considered by many to be a strong candidate in the fight against climate change. This is notwithstanding the potential social impacts and habitat destruction that is commonly associated with such mega damming projects. Here is an illustration of how a typical hydropower plant works.

Illustration from Wikipedia Commons

Hydropower will likely continue to play a key role in future energy production. A study by Lehner et al (2005) correlated the potential of hydropower plants to produce electricity to changes in river discharge. Based on findings from their models, the authors proposed the following scenarios for the 2070s in Europe.

• Scandinavia and northern Russia could see an increase in developed hydropower potential (15–30% and above)
• Portugal and Spain in southwestern Europe, as well as Ukraine, Bulgaria and Turkey in the southeast, could see a decrease of developed hydropower (20–50% and more).
• The United Kingdom and Germany's developed hydropower potential would likely remain stable

This leads one to wonder if hydropower may have its limitations going forward? 

There has thus far been a notion that removing trees along streams would increase surface runoff going directly into streams, and thereby benefit hydropower generation. Challenging this notion, New York Times recently reported on a study by Stickler et al (2013) that considered “indirect” rainfall effects resulting from deforestation generation potential for the Belo Monte energy complex under construction on the Xingu River in the eastern Amazon. Deforestation of the Amazon region inhibited rainfall within the Xingu Basin and simulated power generation declined to only 25% of maximum plant output. 

Apart from rainfall effects, Simoes and Barros (2007) also observed that increased temperatures could lead to increased evapotranspiration rates, which would result in reduced power generation for hydropower plants. In 2001, due to an upward trend in temperature, rainfall fell behind evapotranspiration rates, and reservoir levels dropped to 20% of total capacity. The situation was so severe that the federal government announced a national rationing plan to avoid blackouts. 

The authors therefore cautioned that such climatic variability typically do not capture media attention, but the subtle changes over long periods would accumulate and invalidate assumptions on water availability for hydropower stations, thereby affecting electricity generation.

Therein lies the irony. Although hydropower is viewed by many as a potential solution to global warming, the viability of hydropower itself is at the mercy of climate change. Relevant stakeholders should therefore consider undertaking more holistic analysis that factor in climate change impacts as part of their environmental impact assessments for future hydropower projects.