The Relationship between Greenhouse Gases and 

Hydroelectric Power

Colleen SmithCHE379

Fall 2007

Hydroelectric Power Generation

Environmental Concerns of the 20th Century

Environmental Concerns of the 21st Century

Formation and Release of Biogas

• Anaerobic Digestion– Hydrolysis• Bacteria splits protein

– Acidification

• Requires/depletes Oxygen

– Methanogenesis

– Biogas formed

• Percolates upward out of reservoir surface– As the Methane rises it is oxidized into CO2

• Rapid Release of methane at turbines– Pressure drop causes______

Affect of Biogas on the Environment

• Assume greenhouse gases, such as methane and carbon dioxide, cause global climate change

Affect of Global Warming on Precipitation

Affect of Global Warming on Snowpack

• Decreased snowpack means that more precipitation is turning directly into runoff and adding to streamflow in the winter months

• High flows in winter leave less snow to melt and provide water in the summer

Affect of Global Warming on Snowmelt

• Average time of Snowmelt is in • Warmer weather causes earlier snowmelt• Snowmelt time directly affects streamflow

throughout the year

Affect of Snowmelt on Streamflow• Increased March streamflow• Decreased June streamflow

Affect of these changes on the Grand Coulee Dam

• General Hydroelectric Dam constraints– Prevent downstream flooding– Provide water during dry months– Generate electricity when releasing water

• Increased precipitation, less snowpack, and earlier snowmelt increases chance of flooding

• Less snowpack and earlier snowmelt decreases water availability during the summer

• Hydroelectric power generation is dependent upon flood hazard and water allocation needs

Modeling the Grand Coulee Dam

• HEC-HMS• The 24hr 2yr and

100yr storm• In 2000 and 2050

• Turbine generators and spillway

Affect on The Grand Coulee Dam• In all cases, water flowed over

the spillway• The greatest effect was seen in

the 2yr storm event• Without additional downstream

dams, there would be disastrous flooding

• More additional water means greater potential for hydroelectric generation– If more turbines were installed

2000 2050 % change2yr 2,000,000 2,300,000 15%100yr 3,300,000 3,300,000 0%

TOTAL OUTFLOW

2000 2050 % change2yr 7,500 200,000 2567%100yr 100,000 100,000 0%

SPILLWAY OUTFLOW

Conclusions• Dams produce GHGs

– CH4 and CO2• There is still debate regarding the scale and extent of the

emissions– On a case by case basis

• There are small scale measures that could help– Vegetation Removal

• Underwater logging– Capture of CH4– Ignore methane problems– Do nothing

• Global Warming affects the climate– Increased Precipitation– Decreased Snowmelt– Earlier Snowmelt– Earlier streamflow

• Possible flooding• Could be harnessed with increased hydroelectric generation

– More turbines

Questions?