Science/Ecology

Development of small versus large hydropower in Norway comparison of environmental impacts

Source: 
Science Direct
Year: 
2011
Abstract: 

This study has compared the accumulated environmental impacts from 27 small-scale hydropower plants with 3 large hydropower projects. The results show a slight tendency that large hydropower has a lower degree of impacts than many small-scale projects, but lack of precision in the data and weak methodological foundation introduces uncertainty in the results. Taking into account other benefits such as the provision of regulated power, it is reasonable to assume that a few large hydropower projects will produce electricity to a lower environmental cost compared to many small projects, which should be considered when realizing renewable energy policy objectives.

 

Author(s): 

 Tor Haakon Bakken, Håkon Sundt, Audun Ruud & Atle Harby

Climate Change Effects On The High-Elevation Hydropower System With Consideration Of Warming Impacts On Electricity Demand And Pricing

Source: 
California Energy Commission
Volume: 
Publication number: CEC‐500‐2012‐020
Year: 
2012
Abstract: 

While only about 30 percent of California’s usable water storage capacity lies at higher elevations, high‐elevation hydropower units generate, on average, 74 percent of California’s instate hydroelectricity. In general, high‐elevation plants have small man‐made reservoirs and rely mainly on snowpack. Their low built‐in storage capacity is a concern with regard to climate warming. Snowmelt is expected to shift to earlier in the year, and the system may not be able to store sufficient water for release in high‐demand periods. Previous studies have explored the climate warming effects on California’s high‐elevation hydropower system by focusing on the supply side (exploring the effects of hydrological changes on generation and revenues) but they have ignored the warming effects on hydropower demand and pricing. This study extends the previous work by simultaneous consideration of climate change effects on high‐elevation hydropower supply and demand in California. Artificial Neural Network models were developed as long‐term price estimation tools, to investigate the impact of climate warming on energy prices. California’s Energy‐Based Hydropower Optimization Model (EBHOM) was then applied, to estimate the adaptability of California’s high‐elevation hydropower system to climate warming, considering the warming effects on hydropower supply and demand. The model was run for dry and wet warming scenarios, representing a range of hydrological changes under climate change. The model’s results relative to energy generation, energy spills, reservoir energy storage, and average shadow prices of energy generation and storage capacity expansion are examined and discussed. The modeling results are compared with previous studies to emphasize the need to consider climate change effects on hydroelectricity demand and pricing when exploring the effects of climate change on California’s hydropower system.

Author(s): 

Marion Guegan, Kaveh Madani, and Cintia B. Uvo

Flow Regime, Temperature, and Biotic Interactions Drive Differential Declines of Trout Species Under Climate Change

Source: 
PNAS- Proceedings of the National Academy of Sciences
Year: 
2011
Abstract: 

Broad-scale studies of climate change effects on freshwaterspecies have focused mainly on temperature, ignoring criticaldrivers such as flow regime and biotic interactions. We usedownscaled outputs from general circulation models coupled with a hydrologic model to forecast the effects of altered flows andincreased temperatures on four interacting species of trout across the interior western United States (1.01 million km2), based onempirical statistical models built from fish surveys at 9,890 sites. Projections under the 2080s A1B emissions scenario forecast amean 47% decline in total suitable habitat for all trout, a groupof fishes of major socioeconomic and ecological significance. We project that native cutthroat trout Oncorhynchus clarkii, already excluded from much of its potential range by nonnative species, will lose a further 58% of habitat due to an increase in temperatures beyond the species’ physiological optima and continuednegative biotic interactions. Habitat for nonnative brook troutSalvelinus fontinalis and brown trout Salmo trutta is predictedto decline by 77% and 48%, respectively, driven by increases in temperature and winter flood frequency caused by warmer, rainier winters. Habitat for rainbow trout, Oncorhynchus mykiss, isprojected to decline the least (35%) because negative temperature effects are partly offset by flow regime shifts that benefit the species. These results illustrate how drivers other than temperature influence species response to climate change. Despite some uncertainty, large declines in trout habitat are likely, but our findings point to opportunities for strategic targeting of mitigation efforts to appropriate stressors and locations.

Author(s): 

Seth J. Wengera, Daniel J. Isaak, Charles H. Luce, Helen M. Neville, Kurt D. Fausch, Jason B. Dunham,Daniel C. Dauwalter, Michael K. Young, Marketa M. Elsner, Bruce E. Rieman, Alan F. Hamlet, and Jack E. Williams

Contact: 
Notes: 
Category: 

Improving Environmental Flow Methods Used in California FERC Relicensing

Year: 
2011
Abstract: 

California faces a wave of licensing of dams for power production, with approximately half of the dams scheduled to be licensed over the next 15 years. The number of projects, the cost of the licensing process, and the increased appreciation of the complexity of stream ecosystems, highlight the need for better methods for determining how much water should to be left in the streams, using Environmental Flow Methodologies. The authors examined the range of methods available assessing environmental flows in relation to Federal Energy Regulatory Commission (FERC) licensing processes in California. We specifically sought to integrate insights from allied fields not usually applied to environmental flow methodologies. A particular goal was to see if environmental flow methodologies in use in California are consistent with generally accepted practice in the scientific community, especially in their statistical approaches to problems. The researcher’s basic findings include: (1) environmental flow methodologies used most frequently in California are seriously flawed, including their underlying statistical foundations; (2) alternatives are available (e.g., using Bayesian Networks) that are both more effective and likely less costly; (3) The fish assemblages of California streams have a complex relationship to flows but it is possible to manage regulated streams to favor desired fish assemblages (e.g., endemic fishes); (4) Required monitoring programs for Federal Energy Regulatory Commission projects are generally inadequate and, as a result, have a high probability of leading to erroneous conclusions about the effects of projects on fish populations. The overall results of this research indicate that the efficiency and effectiveness of environmental flow evaluations can be increased, while reducing their costs and providing benefits to both fish and water users. Specific suggestions for improving environmental flow methodologies are provided. 

Author(s): 

Moyle, P.B., J.G. Williams, and J.D. Kiernan

Contact: 
Notes: 
Category: 

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