Hydroelectric Power: Risks and Rewards

Cheap Energy vs the Environment
The Case of Hydroelectric Power

Potential energy = mgh

Historical Growth of Hydroelectric power:

Hydropower is a natural renewable energy source as it makes use of The Hydrological Cycle:

Hydropower production is sensitive to secular evolution of weather; seasonal snowpacks, etc, etc. Long term droughts (10 years or so) seem to occur frequently in the West

About 30% of the hydro-potential in the US has been tapped to date

Why is Hydro so attractive?

Energy density in stored elevated water is high:

So one liter of water per second on a turbine generates 720 watts of power. If this power can be continuously generated for 24 hours per day for one month then the total number of KWH per month is then:

720 watts x 24 hours/day x 30 days/month = 518 KWH/month.

Power generating capacity is directly proportional to the height the water falls. For a fall of say only 3 m, 30 times less electricity would be generated (e.g. 17 KWH/month) - but this is just for a miniscule flow rate of 1 kg/sec.

Capacities of some large dams:

Controversy over the 3 Gorges Dam

Pacific Northwest has 58 hydroelectric dams 63% of total electricity generated. Most of the rest comes from coal fired steam plants (e.g. Centralia Washington).

Note, the Trojan Nuclear Power Plant was relatively easy to shut down because replacement power was immediately available.

Again the main advantages of Hydro are a) its renewable and b) there is a lot of energy available:

Some Real Disadvantages:

Hydroelectric Power - The Risks:

Dams are frequently located upstream from major population centers:

Note that reservoirs offer expanded habitat for geese, pelicans, eagles, osprey. They also help with flood control thus minimizing soil erosion in the watershed.

Adverse effects of dams on salmon:

Solutions:

How will potential lost power be compensated for?

Internet Resources:

  • Overview of Hydropower and the Issues

  • The Columbia River Salmon Passage model (CRiSP)

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