Whilst fooling around yesterday trying to avoid doing work and reading up on the world’s news via Twitter etc, a question popped into my head and sat there like an itch I needed to scratch, an itch to do with climate change and a very widespread, but often neglected form of green energy - hydropower.
As my mind wandered, I began thinking about what effect a globally warming world, with its extreme weather events, climate weirding and melting ice, would have on the frankly massive industry of hydroelectric generation. Would it act to reduce the effectiveness of dams, or actually aid in powering them up; after all, climate change has done some pretty unexpected things in its time, and we are only just scratching the surface of weather system interactions and seasonal skewing.
I decided the best course of action would be to check out a few published papers/journals (of which links are available to at the end of this post) and garner a simple answer to the question, in turn informing anyone who reads this of the conclusions I came to.
I went into this with two polarising thoughts. One, was that climate change, in this instance the global increase of temperatures over the next century or so, would act to reduce the effectiveness of hydropower through the evaporation of reservoirs, rivers and water sources, as well as a reduction in flow of the rivers/system feeding the dams. On the other hand, it may actually increase the power of HE, or at least cause no change at all, by increasing snow-melt, thawing seasons and rainfall, all of which would lead to higher river discharges and a larger water source for energy. So these were my two hypotheses so to speak.
From the three top-cited papers I checked out, there arises a conclusion common in the scientific world, one that I have seen many times over; it’s variable. Now I know this is not enough for a rigorous answer to be put forward, but these papers are at least some of the top in the field of study, and if anything I am attempting to urge further study into it by readers and myself alike, so a future post may probe further, but for now, I’m taking these as a starting point.
The regions of Sweden, California and the Swiss Alps were primarily covered, each reaching effectively the same result. Although there are many instances, especially in the Alps, of negative impacts on HE system performance, there are also many recorded predictions of absolutely no change, or even slight improvements (California study) in performance over modelled periods. It is highly dependent upon where the dam is placed, such as in a water basin which is relatively insensitive to changes in the hydrological state, and reliant heavily upon capacity and so-called timing of the system. The key factor is that climate change can influence this timing by varied but sometimes extreme amounts, leading to associated changes in HE output.
Put simply, in those studies which suggest negative impacts, such as in the Swiss Alps, where the author states possible decreases in performance by as much as 36% under 2070-2099 conditions, it is to do with the intermediate dry periods, during Autumn and Winter months. Climate change may increase rainfall, melt and precipitation in warm months, but at the other extreme, HE systems dry up and energy production slows, with a net negative difference - not good basically. This is reflected in Californian and other Swiss studies, but we are reminded to be cautious of the data and modelling projections.
In contrast, HE performance is positively impacted when the drier months do not overcome the wetter ones, with higher river discharges and rainfall ploughing more water into the reservoirs and dams, upping the juice it can create. Under at least one of these scenarios however, it is the power generation which goes up, not the storage capacity of the system, so in all likelihood, under current dam abilities, we would not be able to harness much of that extra energy when we actually need it, i.e. in the hot summer months when we all want climate control.
These studies and more tend to suggest that we can’t pin down any one direction for HE performance, as subregional impacts are far too variable in their inherent response to temperature and hydrological change. This is a common theme running though climate modelling at this scale, and will require plenty more time for really accurate observations to aid in computer simulation.
Before I finish this admittedly rather short and simple look at one of the many impacts of climate change, I just wanted to share one other thought with you. Iceland, a country with 100% renewables powering its lights, relies heavily on HE power along with geothermal. Now, the latter isn’t running out any time soon, but given the above projections for highly variable and possibly negative impacts on hydropower, are they at higher risk?
Given the large areas covered in ice, I’d be inclined to believe they’re at more risk than many of us. With climate warming comes increased snow and ice-melt, as well as longer thawing seasons and warmer winters, all acting to introduce much more water into the systems than the Icelandic dams might be used to. It’s not hard to imagine summers of intense meltwater inundation, with wild power generation which likely won’t be storable, interspersed with very dry winters, or maybe even further winter melting, or maybe I should come back down to Earth and slow down a little.
What I was trying to get at there is this. It’s highly likely that HE power is going to come under some stress in the coming decades as climate warms and weather systems go a little crazy, and this is likely to affect both power generation and dam integrity. In countries, or states, where HE is a key energy source, I believe it may be prudent to consider them in future policy-making so as to avoid any unexpected changes in the systems, by possibly increasing storage capacities, developing better projection models, or moving steadily away from HE regions which are sensitive to change.
http://hydro-power-generator.blogspot.co.uk/2012/02/hydropower.html
http://www.bioone.org/doi/abs/10.1579/0044-7447-33.4.228
http://meteora.ucsd.edu/cnap/pdffiles/Vicuna_hydropower_jan2008.pdf
http://hal.archives-ouvertes.fr/docs/00/30/56/61/PDF/hess-11-1191-2007.pdf
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