Synthesis

Tremblay, Alain; Varfalvy, Louis; Roehm, C. L.; Garneau, Michelle

doi:10.1007/3-540-26643-7_26

Cited by 9 publications

(24 citation statements)

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“…The limited number of sampling spots may not be able to represent the overall emissions from the reservoirs with complex hydrodynamics 23,30 . Furthermore, the rate of biomass decomposition, and thus the production rates of GHGs, are influenced by geographical location, temperature, water depth, the amount and type of vegetation flooded and reservoir age [6][7][8][9]16,23 . Therefore, development of appropriate, statistically valid sampling strategies and standardization of the analysis methods are essential for consistent emission monitoring.…”

Section: Discussionmentioning

confidence: 99%

“…It is well documented that GHG emissions from most reservoirs in temperate and boreal regions increase dramatically immediately following construction, then decrease over a few years and eventually stabilize [6][7][8]23 . As most of the flooded plant material decomposes in the first 3 years after being inundated with water, the emissions of CH 4 and CO 2 decrease rapidly to levels typical of natural aquatic ecosystems 5 and 10 years later, respectively 6,7,23 .…”

Section: Ghg Emissions From the Tgrmentioning

confidence: 99%

“…As most of the flooded plant material decomposes in the first 3 years after being inundated with water, the emissions of CH 4 and CO 2 decrease rapidly to levels typical of natural aquatic ecosystems 5 and 10 years later, respectively 6,7,23 . Filling of the TGR began in June 2003, and the water level was raised to the normal storage level (175 m) for the first time in October 2010.…”

Section: Ghg Emissions From the Tgrmentioning

confidence: 99%

“…In particular, research over the past two decades has revealed that the decay of organic matter (OM) in reservoirs could release significant amounts of CO 2 and CH 4 , and the emissions from tropical reservoirs characterized by high levels of OM and shallow depths are much higher compared with those in boreal and temperate regions [5][6][7][8][9][10][11][12][13] . Methane is 25 times more effective at trapping heat in the atmosphere than CO 2 over a 100-year period, and is responsible for over 20% of the change in the radiative forcing of the climate system 14 .…”

mentioning

confidence: 99%

“…typically low unless significant sources of nitrogen are present 7 . When dissolved oxygen is available in the water, CO 2 is produced from microbial and photochemical oxidation of OM derived from fallen plant material, sediments and soils, aquatic primary production and from upstream river inputs (Fig.…”

mentioning

confidence: 99%

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The urgency of assessing the greenhouse gas budgets of hydroelectric reservoirs in China

Cheng

2013

Nature Clim Change

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NATURE CLIMATE CHANGE | VOL 3 | AUGUST 2013 | www.nature.com/natureclimatechange C hina overtook the United States and became the world's largest electricity producer and consumer in 2011. The total electricity generation reached 4,722 TW h in 2011, with thermal power and hydropower contributing to 82.5% and 14.0% of the generated electricity, respectively 1 . Meanwhile, over 90% of the thermal electricity is generated by highly polluting coal-fired generation, which had a high grid emission factor of 804 g CO 2 equivalent (CO 2 e) per kW h in 2010 2 . Coal-fired plants are not only the largest stationary source emitters of greenhouse gases (GHGs) in China, but they also bring serious air pollution problems with releases of SO 2 , NO x and fine particles. Hydropower, with more than 200 GW of total installed capacity, accounts for approximately 6% of the total energy supply and over 80% of all electricity generated from renewable sources in China. Joining the global efforts to combat climate change, China is committed to increase the share of non-fossil fuels in its total energy mix to 15% by 2020. Accordingly, the production capacity of hydropower should increase by, on average, 10 to 15 GW yr −1 to help achieve this goal. Cascades of dams are currently being built, planned or proposed on the major river valleys in southwest China, where over two-thirds of the country's hydroelectric resources are located (Fig. 1). With physical water scarcity, and spatially and temporarily uneven distribution of water resources 3 , reservoir development is also a key component of China's recent heavy investment in water infrastructures to adapt to climate change, droughts and floods, and to improve food security 4 .Although hydropower is widely claimed to be a 'clean' energy source, critics have long warned of the environmental impact of large hydroelectric projects. In particular, research over the past two decades has revealed that the decay of organic matter (OM) in reservoirs could release significant amounts of CO 2 and CH 4 , and the emissions from tropical reservoirs characterized by high levels of OM and shallow depths are much higher compared with those in boreal and temperate regions [5][6][7][8][9][10][11][12][13] . Methane is 25 times more effective at trapping heat in the atmosphere than CO 2 over a 100-year period, and is responsible for over 20% of the change in the radiative forcing of the climate system 14 . It has been estimated that large dams release approximately 104 Tg CH 4 annually, or 20% of the total emissions from natural and anthropogenic sources 15 , although current estimations on GHG emissions from global hydroelectric reservoirs bear large uncertainties 13,16 .Carbon dioxide, methane and nitrous oxide are the major GHGs that can be produced in reservoirs, but nitrous oxide emissions are The urgency of assessing the greenhouse gas budgets of hydroelectric reservoirs in China Yuanan Hu, Hefa Cheng* Already the largest generator of hydroelectricity, China is accelerating dam construction to increase ...

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Section: Discussionmentioning

confidence: 99%

Section: Ghg Emissions From the Tgrmentioning

confidence: 99%

Section: Ghg Emissions From the Tgrmentioning

confidence: 99%

mentioning

confidence: 99%

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confidence: 99%

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The urgency of assessing the greenhouse gas budgets of hydroelectric reservoirs in China

Cheng

2013

Nature Clim Change

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Methane dynamics downstream of a temperate run‐of‐the‐river reservoir

DelSontro

Perez

Sollberger

et al. 2016

Limnology & Oceanography

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Dams impact a significant portion of the world's rivers, and rivers downstream of the reservoirs created by large dams often emit significant amounts of methane (CH4). River CH4 emissions downstream of run‐of‐the‐river (ROR) dams are less well known. We investigated spatial and seasonal CH4 dynamics along a stretch of the Aare River (Switzerland) downstream from a bubbling ROR reservoir. We found that the CH4 horizontally accumulated in this vertically non‐stratifying ROR reservoir was consistently transported to the downstream river, but half was lost near a confluence with a tributary. We estimated CH4 diffusion using gas exchange coefficient (k) models that incorporate specific river characteristics and found CH4 emissions were threefold higher upstream of the confluence than downstream. We discuss the use of CO2‐derived k models in estimating k for CH4, and investigated it directly using a drifting chamber experiment. While chamber emissions only partly agreed with the k models, the models were robust enough to use in a CH4 mass balance along the river that indicated an overall CH4 loss from the study area. The loss predominantly occurred at the confluence and > 92% of it could not be accounted for by modelled or measured CH4 emissions. Ultimately, a ROR reservoir that does not form an anoxic, CH4‐rich hypolimnion enhanced downstream river CH4 emissions, but to a lesser extent than other systems (∼9% of total reservoir‐associated emissions). Regardless, small ROR dams and river features such as confluences should be considered when measuring, estimating or upscaling river CH4 emissions.

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The net carbon footprint of a newly created boreal hydroelectric reservoir

Teodoru

Bastien

Bonneville

et al. 2012

Global Biogeochemical Cycles

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143

102

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[1] We present here the first comprehensive assessment of the carbon (C) footprint associated with the creation of a boreal hydroelectric reservoir (Eastmain-1 in northern Québec, Canada). This is the result of a large-scale, interdisciplinary study that spanned over a 7-years period (2003)(2004)(2005)(2006)(2007)(2008)(2009)), where we quantified the major C gas (CO 2 and CH 4 ) sources and sinks of the terrestrial and aquatic components of the pre-flood landscape, and also for the reservoir following the impoundment in 2006. The pre-flood landscape was roughly neutral in terms of C, and the balance between pre-and post-flood C sources/sinks indicates that the reservoir was initially (first year post-flood in 2006) a large net source of CO 2 (2270 mg C m À2 d À1) but a much smaller source of CH 4 (0.2 mg C m À2 d À1). While net CO 2 emissions declined steeply in subsequent years (down to 835 mg C m À2 d À1 in 2009), net CH 4 emissions remained constant or increased slightly relative to pre-flood emissions. Our results also suggest that the reservoir will continue to emit carbon gas over the long-term at rates exceeding the carbon footprint of the pre-flood landscape, although the sources of C supporting these emissions have yet to be determined. Extrapolation of these empirical trends over the projected life span (100 years) of the reservoir yields integrated long-term net C emissions per energy generation well below the range of the natural-gas combined-cycle, which is considered the current industry standard.

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Synthesis

Cited by 9 publications

References 0 publications

The urgency of assessing the greenhouse gas budgets of hydroelectric reservoirs in China

The urgency of assessing the greenhouse gas budgets of hydroelectric reservoirs in China

Methane dynamics downstream of a temperate run‐of‐the‐river reservoir

The net carbon footprint of a newly created boreal hydroelectric reservoir

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