The term “renewable energy” has ironically almost become a dirty word to some conservatives as its use in a sentence reminds them of the impact the green energy revolution has had on fossil fuel development.
Liberals see “renewable energy” as the desperately needed future for global energy requirements and the clear answer for ending global warming. But the oldest and most abundant form of renewable energy has largely been ignored by just about everyone along the political spectrum as the fight for solar and wind additions rages on.
Politics aside, hydroelectric power is a tremendously under-appreciated form of energy production in the United States, and our region, despite it being responsible for 6.5% of our total U.S. energy output. Globally, it accounts for 15% of energy generation.
Some country’s reliance on hydropower exceeds 50% (Iceland, Brazil, Canada and others), while some states in the U.S. use hydro power for as much as 77% of their total energy production. In the western U.S., hydropower makes up an average of roughly 25% of energy output. Idaho relies on hydropower for over 70% of its needs while coal rich Montana produces about 40% of its output from hydro power.
In this issue, Energy Ink will discuss, at length, why this resource is so maligned and ignored, but before taking on the politics, it is important to speak to the basics, and the amazing nature of hydroelectric power.
Water has powered machines for thousands of years. The Greeks used bucket wheels spun by falling water to grind wheat. The electrical application of hydropower came in 1882 with the first hydroelectric dam in the World which produced enough power to run a modern electric heater (one kilowatt). Over 2000 years later, China has built a 22.5 gigawatt hydroelectric dam which could power almost 25 million U.S. homes (and far more Chinese homes.) Over 2,000 dams in America provide about 6.5% of the nation’s electric generation output.
The means by which water is turned into energy is amazingly complex in its simplicity; water falls from a height through a tube; this turns a turbine blade at the end of the tube which causes a generator to turn; energy is produced. But the complex nature of each of these simple processes is the stuff of engineering science.
Quite frankly, only a small portion of Americans understand where their electricity comes from. Only a fraction understand what electricity is. But really, why is it important that we understand such basics? As long as others understand it, and keep the power flowing, isn’t that good enough?
Of course not. Understanding the basics helps us understand the more complex questions about our energy supply. But average citizen aside, you may be hard pressed to find a majority of individuals working in the energy industry who actually understand these basic processes either. Why should they? An area manager for a natural gas company, a rig hand for an oil company, a boilermaker working for a power plant – all are important to the movement of electricity as each are essential components in the process, but none of them really require direct knowledge of how the entire process of power generation works. Just like the front line solider requires up to ten other soldiers in support positions to keep him fighting, our frontline soldier is the electricity that drives our industries, and our most essential coffeemakers. The support positions for this are numerous and include everyone working for a company that transforms resources into energy.
The average energy worker and the average citizen should know some of these basics as well. Moving through life with a mystical understanding of things like electricity leads to a general lack of understanding of the world around us, and the decisions being made about energy on our behalf.
But don’t feel badly if you don’t understand such things. I’d bet your science teacher was boring, or did not know how to teach, or never imparted to you the true importance of electricity. If its never been properly explained to you, how could you understand?
The “Ink” is an all purpose publication. We’re not afraid to tackle the big and complicated issues surrounding the energy industry. But we know that for the more complex issues to really be understood, the most simple of concepts need to be explained as well.
Most understand what a dam is. An existing river is blocked by a structure which creates a lake, or reservoir behind it. Under the water, in the ground, and inside the dam, far more is happening.
On the reservoir side, below the water line, huge pipes called penstocks, connect the reservoir to the power station on the other side of the dam. Water is allowed into the penstocks via an intake tower in the reservoir or through gates on the face of a dam. The power station is below the level of the penstock.
The penstock runs diagonally and below the station where it is funneled into a circular hole which holds a turbine. The Turbine is connected to a generator above it by a metal rod, known as a runner, in the powerhouse floor. As the water spins the turbine and runner, the generator’s rotor spins. The generator creates electricity. But there are a lot of little details which make this simple design work.
Before ground is even broken, a full geological assessment must be done to answer questions of how much water a reservoir can handle. Will the dam cause environmental problems that could harm humans? How much power could the site ultimately provide? Moving labor and land is time consuming and difficult. Reshaping a portion of a landscape takes calculation. The reshaping includes widening or narrowing rock on the river area and providing a firm foundation for the dam. Depending on size, hundreds of thousands of cubic yards of concrete and miles of rebar have to be transported to a usually remote area. The Hoover Dam used three and one-quarter million cubic yards of concrete. It won’t finish curing for many years to come.
Penstocks for a large project are sometimes buried to make a greater leap downward to the power station. Many are large enough in diameter to fit a five story building. An intake is installed at the head of the penstock to control the water flowing through the penstock. These intakes are either steel doors or take the form of an intake tower. Under the power station, the penstock is funneled into a chamber, (some referred to as a scroll case) which holds the turbine. There are three main types of turbines, but all have blades which turn against the flowing water. Water is allowed into an opening at the bottom of the chamber which leads to the draft tube where the water is diverted into the river below. Other means of controlling water flow are through wicket gates surrounding the turbine.
How does it create electricity?
A hydroelectric generator is comprised of a few basic components. The runner, or shaft, which is being spun by the turbine, turns a rotor inside the generator case. The rotor is a circular, cake shaped structure that is plated with electromagnets along the outer edges.
Magnets spinning against the inner wall of the generator, known as the stator, is what generates electricity. The stator wall is comprised of coils of copper wire, called windings. In the most basic terms, as the magnets spin past the windings, electrons are being displaced from their atoms in the copper windings. These free electrons, forced to move through the wires by the magnets in the spinning rotors, are the stuff of what electricity is made. These magnets are known as “electro magnets” because they are actually being powered independently by the exciters. Permanent magnets – those that do not lose their magnetic properties, are impractical for large generators while electromagnets can be turned on and off with the flip of a switch.
Dams typically have more than one generator in operation at the same time. Hoover Dam has 17, and thus, water is diverted into 17 separate, smaller penstocks to 17 separate turbines.
A series of transformers are connected to the generator which converts the generated power to a higher voltage.
Diversion tunnels can be utilized to remove excess reserves during heavy rains or snow melt upstream, allowing water to flow past the generating station down to the river below.
“Fish ladders” are constructed along side of some dams to allow fish to run up river to spawning grounds.
Though comprised of simple components, hydroelectric dams are the result of complex calculations and construction that arguably provide the cleanest source of energy on the planet.