In my last post, I aimed to outline the historical development and production processes of hydropower, although it was difficult to research this subject without becoming distracted by the controversies that surround it. In this post, I will consider the complexities of this renewable resource to see whether hydropower is truly a sustainable and environmentally beneficial source of energy.
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| Barra Grande Hydropower Plant, Brazil Source: Alcoa |
Is Hydropower Sustainable?
I'm sure every geographer has had the UN's definition of sustainability drilled into them from a young age. In the Brundtland report it is defined as "meeting the needs of the present without compromising the ability of future generations to meet their own needs".
Many argue that hydropower is not a sustainable resource as many of its impacts will prevent future generations from meeting their own requirements; displacement of people from their homes, modification of the natural environment and trapping of silt within dams are but a few of the undesirable consequences. Research by Evans et al. (2009), acknowledges these negative impacts but, despite this, hydropower is found to be the most sustainable renewable resource in terms of availability, affordability and efficiency and the second most sustainable resource overall, after wind power.
Another study into hydropower by Yuksel (2010), outlines a number of reasons why hydropower can be considered a sustainable resource. These justifications include: sustaining air quality as it produces no pollutants; potential to limit climate change; a reliable and flexible source of energy; affordable energy for the future due to long life of dams, which function as a source of fresh water, enabling economic and recreational development.
However, a large amount of research demonstrates that there is not a simple yes or no answer to this question, with location significantly influencing how sustainable a hydropower project is. Evans et al. (2009), outlines the importance of taking location into consideration; the research states that although CO2 emissions are relatively low for manufacturing and operating hydropower plants (of the renewable energy sources, only wind power emits less CO2), the type of terrain flooded by the dam has a heavy impact on CO2 emissions. As a result, there are large variations between plants. The more biomass contained within the proposed hydropower site, the higher emission levels, therefore tropical regions have the highest emissions, but this decreases with age as decay takes place.
Frey & Linke (2002), also recognise that the sustainability of a reservoir hydropower plant is dependent on the environment in which it is built. Although dam creation can impact migration of fish and cause the loss of terrestrial habitats, it can also provide flood control and water for irrigation; these impacts are case specific with some plants having more adverse affects than others.
Another factor to take into consideration is the type of hydropower plant being commissioned. Ere & Milewski (2002), acknowledge that modification of the natural environment, and alteration of sediment flow, is far smaller when run-of-the-river projects are used. However, the trade off is the reduction in energy generation and inability to rapidly meet unexpected demand.
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| Jochenstein Run-of-the-River Hydropower Plant, Germany Source: Verbund |
The Impact of Climate Change
Hydropower is a controversial issue for another reason: these dams rely upon the hydrological cycle to create energy, however there is wide acknowledgement throughout the scientific community that hydrology will be affected by anthropogenic climate change. The magnitude and spatial distribution of this impact is unclear - while some areas many benefit from heavier rainfall, others many face periods of prolonged drought.
California's widely reported current water shortage is a good example of how changes in hydrology can impact a region's energy generation. California is currently facing the biggest drought in recorded history and research by the Pacific Institute found that between October 2011 and October 2014, hydroelectricity decreased by 34,000 GWh. On an average year, 18% of electricity is produced by hydropower, but with the persisting drought this has decreased to less than 12%. With water flow to the turbines steadily reducing, hydropower electricity generation is likely to decrease even further.
To conclude...
I started this post as a keen advocate of hydropower and felt it was one of the key solutions for fossil fuel divestment; it provides a clean source of energy as well as the reliability required by nations to meet immediate high demand. However, whilst researching the subject for this post, I have changed my opinion. Don't get me wrong, I don't think future sustainable energy plans should eliminate hydropower, but I do think that there needs to be careful consideration before construction and the impacts of hydropower need to be considered on a case by case basis.
As we have seen, the extent that a hydropower plant meets the needs of today as well as those of the future depends on location. It is therefore critical that hydropower plants are as low impact as possible, which can be achieved through careful assessment of the surrounding ecosystems and selecting the most appropriate size and type of plant for the environment.
However, the impact of climate change on hydropower must also be considered. The alterations in the hydrological cycle due to global warming are hard to predict and as a result, I don't feel that hydropower can continue to be relied upon as the primary renewable energy source. I still believe hydropower capacity should continue to increase because it is an important part of meeting the global energy demand; however, this responsibility must be shared amongst other sustainable technologies to prevent periods of insufficient supply should climate change severely affect the hydrological cycle in future.
Great post, Anna. I found the point you make via Frey & Linke, 2002, about the positives and negatives of dam creation interesting. it made me consider how flood control and flow management are potentially going to be increasingly important methods of building resilience in the face of more extreme storm and flood events based on potential future stormier scenarios. A balanced approach would be ideal i.e. hydropower installations used in conduction with spillways and ecosystem services.
ReplyDeleteThat's a really interesting point Geoffrey and one I actually hadn't considered. Although I mentioned that hydropower may become difficult in areas with increasing drought, I hadn't considered that major storm events are also likely to increase with climate change therefore reservoirs could potentially be used as flood control.
DeleteThis is again a demonstration of how each hydropower plant must be considered on a case by case basis!
Fruitful discussion! This is helpful to Nepal like country where hydropower is at top priority for energy generation ! I think majority of hydropower have impact on ecosystem however we have to adopt them if it is the best alternative to us. The question during decision should be 'is there other better alternative which better serves the people with least harm on environment?
ReplyDeleteI completely agree Bishal- if there are other sustainable alternatives, they should certainly be used in place of hydropower if the natural ecosystem is going to be severely affected.
DeleteThe difficulty that I found during my research is that the majority of other renewable resources aren't able to supply energy at a moments notice when energy demand requires it. For both developed and developing countries, this is of course crucial and puts hydropower as a top contender for governments.