"So while the dam is serving some other purpose (flood control, producing a reservoir, recreational area, etc.) we are just throwing away the energy that could be produced by it. Why weren’t they built that way in the first place?
Cheap oil. Hydro is more reliable than wind, more constant than solar, and except for the initial build (which will last longer than either turbines or solar farms) has a smaller carbon footprint than most other sources."
There were thousands of small dams that generated power. Mostly built a LONG time ago and they served small ‘cities’ at the time. Now that output is trivial.
Many dams have been ‘eliminated’ by those seeking to return rivers to ‘their natural state’.
Hydropower has it’s problems with frozen lakes, lack of enough water flow, too much water flow, stuff blocking the intakes, etc.
Just like there there tens of thousands of ‘grist mills’ using water power, and entire industries back east built on rivers to use water power to run all the machinery… one by one they got replaced by fossil fuel and steam engines… more reliable. When commercial A/C power came along, they converted to electricity. Go back east and there are thousands of factories (or what used to be factories) along rivers that were centers of manufacturing.
Unless you have good year round water flow (big river), hydropower can be a problem. Not every river is Niagara Falls or the Columbia River.
Heck, even Lake Mead is going to get to the point in a few years where it won’t generate any power - no rainfall…lake down a couple hundred feet already and dropping month by month. Hoover Dam might be ‘out of juice’ soon.
Meanwhile, out west, ‘conservationists’ are seeking to remove dam after dam. Let the salmon run. Who worries about floods?
Is there enough water flow at most dams to generate significant hydro? It really depends upon the ‘head’. You need hundreds of feet and large water flow to generate much power. A few KW or 10s of KWs is nothing.
"The power output of a dam is calculated using the potential energy of the water and can be found using the following hydropower formula:
P = ? * ? * g * h * Q
P is the power output, measured in Watts
? is the efficiency of the turbine
? is the density of water, taken as 998 kg/m³ (you can change it in advanced mode)
g is the acceleration of gravity, equal to 9.81 m/s² (you can change it in advanced mode)
h is the head, or the usable fall height, expressed in units of length (meters or feet)
Q is the discharge (also called the flow rate), calculated as Q = A * v
A is the cross-sectional area of the channel
v is the flow velocity