Featured Research

from universities, journals, and other organizations

Greenhouse gas impact of hydroelectric reservoirs downgraded

Date:
August 1, 2011
Source:
Cary Institute of Ecosystem Studies
Summary:
Scientists have amassed the largest data set to date on greenhouse gas emissions from hydroelectric reservoirs. Their analysis posits that these human-made systems emit about one-sixth of the carbon dioxide and methane previously attributed to them.

Located in the State of Mato Grosso, the APM Manso Dam impounds the Manso River and has a capacity of 5,600,000,000 m3 and a surface area of 357 km2.
Credit: Fábio Roland

An international team of scientists has amassed the largest data set to date on greenhouse gas emissions from hydroelectric reservoirs. Their analysis, published August 1 in the online version of Nature Geoscience, posits that these human-made systems emit about 1/6 of the carbon dioxide and methane previously attributed to them.

Prior studies based on more limited data cautioned that hydroelectric reservoirs could be a significant and large source of both carbon dioxide and methane to the atmosphere.

Through an analysis of 85 globally-distributed hydroelectric reservoirs, the authors revealed that these systems emit 48 million metric tons of carbon annually, a downgrade from earlier estimates of 321 million metric tons. Further putting things in perspective, hydroelectric reservoirs are responsible for less than 16% of the total carbon dioxide and methane emissions from all types of human-made reservoirs combined.

"Our analysis indicates that hydroelectric reservoirs are not major contributors to the greenhouse gas problem," comments Dr. Jonathan Cole, a limnologist at the Cary Institute of Ecosystem Studies and one of the paper's authors. "But there are some caveats. To date, only 17% of potential hydroelectric reservoir sites have been exploited, and impacts vary based on reservoir age, size, and location."

Carbon dioxide and methane are two of the main greenhouse gases created by human activities. Carbon dioxide is produced during the combustion of nearly any organic material; methane has a variety of industrial sources. Both gases are also produced naturally, particularly in wetlands and lakes.

When rivers are dammed to make the reservoirs needed for hydroelectricity, flooding creates lake-like conditions that generate carbon dioxide and methane. Emissions are the highest following reservoir construction, due to decomposing vegetation and soil organic matter. As reservoirs age, emissions decline, with cold-water systems stabilizing more rapidly than their warm-water counterparts.

Lead author MSc. Nathan Barros, of the Federal University of Juiz de Fora further explains, "The bottom line is that per unit of energy, hydroelectric generation produces much less carbon dioxide and methane emissions than previously thought, but impacts are not equal across all landscapes."

The amount of greenhouse gases generated by hydroelectric reservoirs depends on where they are built, with the team's analysis indicating that emissions are correlated with latitude and the amount of biomass in the watershed. With Barros adding, "Reservoirs in tropical locations, such as the Amazon, emit more methane and carbon throughout their lifecycles."

Hydroelectricity supplies an estimated 20% of the world's electricity and accounts for more than 85% of electricity from renewable sources. Future development is expected globally.

The paper's authors urge careful consideration of site location and design. "During the environmental impact phase, it should be a goal to minimize the amount of carbon dioxide and methane emitted per unit of energy generated," Cole notes.

To truly tease apart the emissions generated by hydroelectricity, the authors also call for a study that assesses a site's carbon budget before and after reservoir construction. Pre- and post flooding analysis would clarify the net carbon impact of hydroelectric reservoirs.

Other contributors to the paper included Drs. Lars J. Tranvik, Yves T. Prairie, David Bastviken, Vera L. M. Huszar, Paul del Giorgio, and Fábio Roland.

The work was supported by grants from FURNAS Centrais Elétricas and from the Swedish Foundation for International Cooperation in Research and Higher Education (STINT).


Story Source:

The above story is based on materials provided by Cary Institute of Ecosystem Studies. Note: Materials may be edited for content and length.


Journal Reference:

  1. Nathan Barros, Jonathan J. Cole, Lars J. Tranvik, Yves T. Prairie, David Bastviken, Vera L. M. Huszar, Paul del Giorgio, Fábio Roland. Carbon emission from hydroelectric reservoirs linked to reservoir age and latitude. Nature Geoscience, 2011; DOI: 10.1038/ngeo1211

Cite This Page:

Cary Institute of Ecosystem Studies. "Greenhouse gas impact of hydroelectric reservoirs downgraded." ScienceDaily. ScienceDaily, 1 August 2011. <www.sciencedaily.com/releases/2011/08/110801134733.htm>.
Cary Institute of Ecosystem Studies. (2011, August 1). Greenhouse gas impact of hydroelectric reservoirs downgraded. ScienceDaily. Retrieved July 24, 2014 from www.sciencedaily.com/releases/2011/08/110801134733.htm
Cary Institute of Ecosystem Studies. "Greenhouse gas impact of hydroelectric reservoirs downgraded." ScienceDaily. www.sciencedaily.com/releases/2011/08/110801134733.htm (accessed July 24, 2014).

Share This




More Earth & Climate News

Thursday, July 24, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Goma Cheese Brings Whiff of New Hope to DRC

Goma Cheese Brings Whiff of New Hope to DRC

Reuters - Business Video Online (July 24, 2014) — The eastern region of the Democratic Republic of Congo, mainly known for conflict and instability, is an unlikely place for the production of fine cheese. But a farm in the village of Masisi, in North Kivu is slowly transforming perceptions of the area. Known simply as Goma cheese, the Congolese version of Dutch gouda has gained popularity through out the region. Ciara Sutton reports. Video provided by Reuters
Powered by NewsLook.com
Higgins Breaks Record at Mt. Washington

Higgins Breaks Record at Mt. Washington

Driving Sports (July 24, 2014) — Subaru Rally Team USA drivers David Higgins and Travis Pastrana face off against a global contingent of racers at the annual Mt. Washington Hillclimb in New Hampshire. Includes exclusive in-car footage from Higgins' record attempt. Video provided by Driving Sports
Powered by NewsLook.com
Storm Kills Three, Injures 20 at Virginia Campground

Storm Kills Three, Injures 20 at Virginia Campground

Reuters - US Online Video (July 24, 2014) — A likely tornado tears through an eastern Virginia campground, killing three and injuring at least 20. Linda So reports. Video provided by Reuters
Powered by NewsLook.com
Creative Makeovers for Ugly Cellphone Towers

Creative Makeovers for Ugly Cellphone Towers

AP (July 24, 2014) — Mobile phone companies and communities across the country are going to new lengths to disguise those unsightly cellphone towers. From a church bell tower to a flagpole, even a pencil, some towers are trying to make a point. (July 24) Video provided by AP
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
 
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:  

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

    Health News

      Environment News

        Technology News



          Save/Print:
          Share:  

          Free Subscriptions


          Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

          Get Social & Mobile


          Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

          Have Feedback?


          Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
          Mobile iPhone Android Web
          Follow Facebook Twitter Google+
          Subscribe RSS Feeds Email Newsletters
          Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins