On Sundays, I like to spend in the afternoon, with the grace of my wife and sons, some time in the Engineering Library, and lately I've taken to checking out the "new books" section, which always has one or more books that immediately catch my eye.
Today one new book that caught my eye was Modelling the Impact of Climate Change On Water Resources, published by Wiley and Sons this past December.
I have written before in this space about my (admittedly very grudging) support for one form of so called "renewable energy," hydropower, several times - including my favorite, A Tale of Two Centimeters: The Near Collapse of the Colorado River Dam System in 1983. I also wrote about so called "renewable energy" and the Pantanal - the world's largest wetland - in this space: Those Happy Sugarcane Workers In Brazil: The Car Culture and Urinary Carcinogens. The paper from the primary scientific...
...literture that I will discuss today, in this brief diary, was brought to my attention while checking references found in the "new book" referenced above, coming across an article The impact of global change on the hydropower potential of Europe: a model-based analysis and viewing citing articles. The paper to be discussed (briefly) is called "Hydrological changes in the northern Pantanal caused by the Manso dam: Impact analysis and suggestions for mitigation" and is published in the following reference: Ecological Engineering Volume 35, Issue 1, 8 January 2009, Pages 105-117
Despite 50 years of reciting - much as Pope after Pope recites The Lord's Prayer - the mantra that "solar energy will save us," and "wind energy will save us" and "geothermal energy will save us," the world's largest, by far, source of so called "renewable energy" used for power generation remains exactly as it has been for more than a century, hydroelectricity. It is also the world's fastest growing form of so called "renewable energy," although the number of free flowing rivers on the planet is rapidly approaching, um, zero.
(The fastest growing form of climate change gas free primary energy is nuclear energy. Arguably, as shown by Phillip Morrison half a century ago, nuclear energy is renewable energy, but, I am not here to malign nuclear energy by comparing it to what are generally believed forms of so called "renewable energy," hydro, wind, geothermal and solar, in order of production.)
Some remarks from the paper:
The impacts of dams on ecosystems are well known and generally differentiated into upstream and downstream effects (Nilsson et al., 2005). Upstream impacts include the flooding and fragmentation of ecosystems, the production of greenhouse gases by reservoirs, degradation of water quality, and an increase of water-borne diseases. The dams disrupt sediment transport and fish migration when their operation schemes alter the flow regime of rivers downstream, reducing or increasing flows, modifying seasonality of flows, changing the frequency, duration, magnitude, timing, predictability and variability of flow events, altering surface and subsurface water levels, and changing the rate of water level increase or decrease (Poff et al., 1997; Nilsson and Berggren, 2000). These alterations are widely recognized as major contributing factors to the loss of biological diversity and ecological functions in aquatic ecosystems, as well as the overall loss of the ecosystem services on which the human economy depends (Postel, 1998).
"Well known?" Really? I claim - and I think that I'm something of an expert on this matter - that anyone who questions the rote assumption that so called "renewable energy" is anything other than perfect is likely to generate a lot of negative feedback from people who know very little about energy's external costs, but that would be my opinion. But let me not disagree with the authors of the paper too vociferously.
The authors prattle on claiming that, um, that this form, hydro, of so called "renewable energy" has other effects.
Concerns about downstream impacts carry additional weight if river regulation occurs in the headwater regions of large floodplains (Frazier and Page, 2006; Kingsford, 2000). Alterations of the spatial and temporal occurrence of water cover will interfere with both biogeochemical fluxes and hydromorphism of soils, and, therefore, with biota adapted to these hydrological periodicities (Hu et al., 2008; Iriondo, 2004; Gopal and Junk, 2000). Maintenance of natural flood pulse is essential, as the water level fluctuations and the change between pronounced terrestrial and aquatic phases are the driving force in floodplain systems, connecting permanent water bodies through a moving littoral zone by an Aquatic–Terrestrial Transition Zone (Junk, 2005; Junk and Wantzen, 2004; Junk et al., 1989). Neiff et al. (1994) pointed out that the biocoenosis of large rivers is regulated by the hydrodynamicism of their pulses, but that low water phases are as important as flood periods.
Junk and Nunes da Cunha (2005) as well as Junk et al. (2006) provide an overview of the ecology of the Pantanal of Mato Grosso, which, with an area of about 160,000km2, is the world’s largest floodplain. These authors point out that its distance frommajor consumption centers and inaccessibility has hindered the economic development of the Pantanal, thus it is considered to be in rather pristine condition.
Um, Junk science. (Sorry, I couldn't resist.)
Junk's claim that the Pantanal is nearly pristine will soon pass into history:
Presently, 7 great (UHE, >30 MW), 16 small (PCH, 1–30MW) and 6 very small (CGH, <1MW) hydropower plants are located in the Pantanal catchment (ANEEL, 2008), but only the Manso plant (220MW)has a large reservoir. Its filling phase was begun in November 1999 and concluded in 2002. At maximum water level, the reservoir covers about 427km2, with a total volume of about 7.3km3. Hydropower supplies more than 80% of Brazil’s electricity (Brasil. Ministério de Minas e Energia, 2007), and with an annual increase in energy demand of about 4.5% (2000–2005), there is no reason to believe that pressure for additional generation capacity will decrease in the near future. Three of 42 plants currently planned at tributaries in the Pantanal catchment have projected capacities higher than 100MW.
Bye, bye, Pantanal. One of the things associated with the form of so called "renewable energy" represented by hydroelectricity is, um, evaporation. Indeed, in the book referenced at the beginning of this diary (cf page 149) the authors of case studies write:
The effect of climate change on hydropower potential is twofold [Arnell 1996): changes in magnitude and seasonality of inflows will first affect either the shape of the reference flow duration curve for run of river schemes or the storage for systems based on reservoirs. Additonally, possible increases in evaporation may significantly reduce storage volume in tropical areas
Tropical areas? Say, um, isn't that where, um, Brazil is?
Anyway, the authors go through lots of "sciency" stuff in their paper about measuring water flows, blah, blah, blah. The bottom line is that the water flows in the seasonal dry season are reduced downstream from the dam about 30%, less than 10% in the wet season.
They propose changes in the power generation schemes to mitigate these effects.
But mitigation is not the same as, um, "pristine," the words used to describe the Pantanal until, um, recently.
The Pantanal is doomed anyway, by ethanol farms, and by changes in runoff due to logging, a matter that is also referred to in the paper. For the short term, logging as actually increased flows into the Pantanal, and paradoxically, one can expect that the accumulation of sediment connected with the destruction of upstream forests will affect the lifetime of the "renewable" hydroplants.
For the record, Brazil is currently considering building four nuclear plants. Nuclear plants are not generally hydrologically neutral, although, truth be told there is no practical reason that they need to be hydrologically disasterous to function. Currently Brazil produces about 3% of its electricity using nuclear energy.
Have a nice day.