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HydroElectric Power: Risks and Rewards

Cheap Energy vs the Environment
The Case of Hydroelectric Power

Historical Growth of Hydroelectric power:

Currently Hydro power is 7% of the total US Energy Budget. This has been going decreasing with time
This varies considerably with region in the US due to the availability of freely flowing streams
Dam building really was initiated in the 1930's as part of a public works program to combat the depression
Low cost per KWH (see below) caused exponential increase of dam building from 1950-1970 (lots of this on the Columbia)
Since 1970 hydroproduction has levelled off and therefore becomes an increasingly smaller percentage of the US energy budget.

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 hydropotential in the US has been tapped to date

Why is Hydro so attractive?

BECAUSE ITS CHEAP! for the consumer

average price in the PNW is around 4 cents per KWH

this is 3 times less than the national average!

Low cost to the consumer reflect relatively low operating costs of the Hydro Facility. Most of the cost is in building the dam

Operating costs about 0.6 cents per KWH

Coal Plant averages around 2.2 cents per KWH

which reflects costs of mining, transport and distribution.

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 genreated 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:

Grand Coulee            1942 6500 MW
John Day                1969 2200 MW
Niagara (NY)            1961 2000 MW
The Dalles              1957 1800 MW
Chief Joseph            1956 1500 MW
McNary                  1954 1400 MW
Hoover                  1936 1345 MW
Glen Canyon             1964  950 MW
Three Gorges            2000 18000 Mw

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:

1918--1958: 33 Major dam failures resulting in 1680 documented fatalities
1959--1965: 9 major dams failed throughout the world
1976: Teton Dam failure in Idaho
Most of the dams on the columbia have been built since 1950 and are not close to their failure points
The Salmon Problem:
- Extremely Emotional Issue --> icon of the PNW
- Some Federal Dam Licenses can now be lost because of salmon migration problems
  - Some studies suggest Federal dams are mostly resonsible for drop from 16 million to 300,000 wild fish per year
  - Actual Salmon Count data is available for these dam sites:
- Estimated that to improve migration, utility rates will rise in the PNW by 8%
- There are lots of other factors at work as well:
  - El Nino
  - Agressive Fishing
  - Poor logging practices and increased soil erosion

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:

migratory barrier

killed in turbines (especially young ones swimming downstream)

supersaturation of air in water (high pressure of water falling down forces air into the solution)

reduced oxygen content if river flow is reduced (summer) due to separation of warm and cold water; cold water doesn't mix to be aerated (this is mostly a problem in the Tennesee Valley)

Solutions:

Build fish "passages" to direct them towards tributaries this has proven successful for trout in Oregon
Better turbine design and screen systems can help eliminate fishkill on the downstream migration
Minimize turbulence in the operation of the turbine
Have better flow control

How will potential lost power be compenstated for?

energy conservation?
sale of hydro to the US by Canada?
Coal-fired plants?
wind?
solar?
nukes?

Internet Resources:

Overview of Hydropower and the Issues

The Columbia River Salmon Passage model (CRiSP)

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