Water is our life's blood. Our bodies thrive on it. Civilizations rise and fall from its use. Water also provides power. Ancient civilizations perfected methods to use the power provided by water to simplify their tasks.
Niagara Falls
Prologue
Ancient societies like the Greek, Roman Empire, and the Han Dynasty learned to harness the power of water to perform many of their tasks (Alberta).
They developed water wheels, for instance, to convert the kinetic energy of flowing water into the mechanical power needed to simplify tasks like grinding grain or breaking ore (IHA).
It wasn't until the late 1800s that humanity began using the power of water to create electricity.
Introduction
Image by bluebudgie from Pixabay
Welcome, fellow Steemians, to our fifth installment in the Energy series. In this post, we will discuss hydroelectric power and build upon the information presented in our first installment (Energy - Overview).
Basics of Hydroelectric Power
Reviewing the above diagram shows that water, at a higher elevation and pressure, flows past the dam's sluice gates and reaches the turbine past the penstocks. When the water reaches the turbine, it begins pushing past the blades of the turbine, causing it to turn. The rotating turbine spins a generator that produces electricity.
The electricity generated passes to the transformer. The generated voltage is stepped-up to a rating sufficient enough to overcome the resultant heat losses that occur during the transfer to the end-user.
Types of Hydroelectric Plants
The technology primarily responsible for hydroelectric power exists in the forms discussed below.
Impoundment
The impoundment-type of a hydroelectric plant is what we're likely most familiar within our lives. Do you recall the Hoover Dam? Perhaps you've heard of the Three Gorges Dam? Those are hydroelectric plants that use a dam as a means of water supply to the plant. The diagram we recently discussed above is an impoundment-type hydroelectric plant.
Creating the dam creates a reservoir of water that allows for a controlled flow from the reservoir to the turbine and generator (Energy.gov). Operators can adjust the flow of water as needed to control the power output of the facility ultimately.
Operators are also able to adjust the position of the blades of the turbine to receive the highest flow rate and pressure of water.
Diversion
Image by stanbalik from Pixabay
Have you heard of the Niagara falls? My parents once brought me there when I was a child. It was one of the first places I ever visited outside my home. I remember its beauty even today. Once I started learning of power production, however, I never in my wildest dreams thought it was producing electricity. It fascinates me today that we could accomplish such a feat.
The diversion type of hydroelectric plant operates similarly to an impoundment type. The difference here is that a damn is not always required. The Niagara falls diversion type facility diverts about 1.2 million gallons of water per second to turbines that, as discussed, rotate to drive a generator to create electricity.
Pumped storage
Pumped storage hydroelectric plants operate similarly to the two previously discussed. The main difference is that the facility adds a reservoir for storage. The intent is to use the added water to supplement electrical generation when necessary. The concept is useful when water levels are too low or when electrical demands become challenging.
Environmental Impact
Every form of power we've discussed in this series impacts the Earth in some way. Some have more significant impacts than others.
Image by Steve Buissinne from Pixabay
Coal, for instance, impacts the Earth primarily in its creation of coal ash and airborne pollutants. The abundance of coal, coupled with the familiarity society has with its technology, means it has a significant impact on how its operations can affect the Earth. Virtually every developing and advanced country on this planet will use coal despite its effect on the environment.
Nuclear power plants, on the other hand, aren't as widespread as coal facilities. However, the environmental ramifications from the misuse of nuclear could affect regions for centuries. Remember our discussion on Chernobyl and Fukushima? It will take decades before we can even consider re-populating some of the affected areas.
Environmental Disaster of Solar Energy
Even precious Solar Power has its issues. While, in my opinion, solar power's impact is minimal compared to coal and nuclear, it's something we still have to consider. We must be responsible and scrutinize every large-scale project that promises "free" and "clean" energy that is not upfront with the hazards it poses.
Hydroelectric power is no different. No matter how beautiful the scenery or convenient the method, roads paved with only the advertised good intentions lead to one direction.
Land and Water Use
Human Toll
Industrial and nuclear accidents may lead to the evacuation of devastated or contaminated areas after an event. The Fukushima and Chernobyl nuclear accidents saw the evacuation of hundreds of thousands of people. It affected and will continue to change many generations to come. Sometimes, however, when society builds a dam, it affects the local population even before the power plant starts to run.
The Three Gorges dam in China is, arguably, one of the most significant power production projects on the planet. The design capacity of 22.5 Gigawatts is mind-boggling. The reservoir is 400 miles long with hundreds of gates and 26 turbines (Reuters). The dam has a max power output of approximately 11 nuclear power plants. The facility has such a wide area of operation for its reservoir that China had to force-relocate well over one million people. China even constructed a new town to house those relocated (Reuters).
Water Quality
If you add to an ecosystem, you affect that ecosystem. It doesn't matter how benign the activity. The principle applies to virtually anything on Earth.
In the case of dams, you are adding a large facility that will divert, stop, start, or adjust the flow of water. Stagnant water may lead to the growth of harmful algae that did not exist in the past. Wastes and chemicals once filtered by the flow of water may accumulate because the source waters are no longer free-flowing (American Rivers).
Changing the pace of a river also affects local habitats. It will cause a change in the river temperature that leads to the killing of species of fish or algae and replace it with something that can survive that is much worse (American Rivers).
Accidents
Sayano-Shushenskaya Hydroelectric Dam, Russia
In August of 2009, a 1500-ton turbine blasted through the floor of the facility and 50-ft into the air before crashing (Popular Mechanics). The damage from the explosions released 40-tons of oil to the associated river. 400-tons of fish died from the contamination. Investigations cited faulty repairs, upgrades, and management oversight as the causes of the accident (Popular Mechanics).
Technology Summary
Hydroelectric power plants use water as a renewable fuel source. Unless a drought occurs, the water will return to the reservoir in cycles.
These plants can also change power quickly. They could go from shutdown to full power relatively quickly to meet virtually any power demand. Coal and nuclear power don't move that fast. Oh, and commercial nuclear power plants provide only base loading. They can't just raise and lower power for safety reasons.
While experts advertise hydroelectric power as clean, they typically mean "clean" concerning greenhouse gasses. Again, the loopholes appear astounding. It was a shock to me to discover that bit of information.
It is saddening that politicians appear to adjust the meaning of "clean" when speaking about renewable energy sources. Yes, using hydroelectric power produces ZERO greenhouse gases. However, in terms of environmental impact, hydroelectric isn't benign. You impact the environment the moment construction starts, and the effect continues to be harmful during operation.
One thing I also noticed was the purpose of hydroelectric power and dams in general. They exist solely to support humanity. Are they even necessary? Perhaps so, since our only options are forms of energy that pollute the environment. "Picking your poison" seems to be a relevant saying in hydro's case.
In Closing
Thanks again, fellow Steemians, for following on with this series. Our next article will be on wind power generation and covers similar topics as coal, nuclear, solar, and hydro.
