The Power of the Waves

After learning about solar and wind power, I thought hydropower would be a great next topic.  Hydropower is the most common source of renewable energy, as it accounts for about 67% of the United State's total renewable energy production.  First, let's talk about how hydropower works.  Hydropower uses the force of falling water to turn the turbine of a generator.  The water pressure is usually built up by damming a river, and then channeling the water down a large pipe called a penstock.  This increases the water pressure.  After the water turns the turbine, it flows back into the river on the other side of the dam.  This is a renewable source of energy because of the water cycle.  The water that flows out from the penstock will eventually evaporate and start back at the source of the river by rain, snow, or other precipitation.

Hydropower sounds simple enough, but there are several things that need to be considered.  Salmon are fish that swim upstream to spawn.  After spawning, the salmon and their offspring need to swim downstream to return to the ocean.  Damming a river makes it nearly impossible for these salmon to get upstream to their spawning grounds.  Even if they did get upstream, they could easily be killed by the dam on the way back down.  To prevent this problem, dams in rivers where salmon migrate have installed fish "ladders".  These fish ladders are simply a passage around the damn with a serious of steps.  The water flows fast enough over these steps to attract the fish but slow enough that they can leap over them without be washed back down.  

The Grand Coulee Dam in Grand Coulee, Washington produces more power than any other hydroelectric dam in the United States.  Although this dam produces billions of kilowatts of power annually and irrigates about 600,000 acres of farmland, it has no fish ladder.  This dam removed about a thousand miles of spawning grounds for several types of salmon.  This dam, like many others, has its pros and cons.  It is up to you to decide which outweighs the other.  A great video about hydropower can be found here : video. 

One of the Grand Coulee Dam's 33 turbines being assembled