It's been a long time for this blogger! I have a long post coming on some fishing escapades over the last few months, but we finished watching DamNation the other day and I thought I'd write some quick thoughts on it.As an energy engineer by trade, I have some knowledge of infrastructure required for our society to continue to operate and expand, especially in how energy is generated and distributed.
There are many dams that are obsolete and/or in various stages of disrepair. There are many dams that are completely functional and maintained to stay that way for the foreseeable future.
The tributary to Lake Ontario, right in the heart of our city, has four dams I can think of that are local to our Lower Genesee Valley region. Of the four, three are hydroelectric dams with a total rated capacity of 56.9 MegaWatts, theoretically supporting the electricity needs of ~22,700 households.
I'll try not to go very far into this boring stuff, but I was trying to get to a couple points the filmmaker seemed to miss just a little.
Exhibit A) Hydroelectric dams provide some power generation redundancy. Every single power generating station has a metric called a Capacity Factor. It's simply the ratio between it's actual generating capacity and it's rated capacity. Hydro power sources tend to be lower than fossil fuel plants due to their "fuel" source (fluctuating renewables). Nationally, hydropower fluctuated between ~50% capacity factor in May 2013 and lulled at ~30% in August 2013, continuing that pattern throughout the year. On the other end of the spectrum, nuclear power fluctuated between ~98% capacity factor and 78% throughout the year. Fossil fuel power has the same fluctuation at a lower percentage, between 40-70%.
What all this is supposed to tell you is that because power generation capacity is cyclic, there has to be built in redundancy. Broken down to regional effects, those three dams usually provide power to between ~7,000-11,000 homes. This means the other ~11,700 homes need power from elsewhere. Our electricity comes from coal, from nuclear, from hydro, and it changes, sometimes every day. There's a reason blackouts are very few and far between.
One last point:
Exhibit B) Flood control. If you've ever visited Letchworth State Park, you've likely seen the Mt. Morris dam. What you may not know is prior to the dam's construction, the City of Rochester was subject to terrible flooding on a seven year cycle from the early 1800's until the dam's completion in 1952. I look at the river's gauge prior to a day's fishing and the maximum discharge of 29,600 CFS always catches my eye. That occurred back in 1972 during Tropical Storm Agnes. The reservoir was filled almost to the brim and the dam operators were forced to flow the maximum volume of water through the gates, producing only minor flooding to points downstream. The dam was estimated to have saved $210 million in damages from that event alone and over $1 billion in its lifetime. The previous maximum discharge occurred in 1865. Take a guess at what that volume was.54,000 CFS! That is half of what Niagara Falls flows! Some of you have fished below the lower falls in the city. Can you imagine that volume of water? Some of you were alive in 1972 and saw with your own eyes what 30,000 CFS looked like flowing through the river. Double that flow and you begin to realize the economic impact Rochester would have to absorb if we didn't have the Mt. Morris dam.
I'm no pro-dam advocate, neither am I against them. The geologist at the end shares my thought process on dam removal. There should be an impact assessment study associated with the project. If feasibility is justified, proceed. But the fact of the matter is politics and funding come into play along the way with these projects. There are many other public works that our tax payer dollars can be devoted to and money tends to be spread thin. The angler in me loves the premise of the movie, but the engineer in me realizes the economic asset dams can be. It's a tight line to walk on...
