# What is the relationship between gravity and penstock

### Pipeline: Hydro-Electric Penstock Design | Home Power Magazine

Animation of a hydroelectric power plant in a dam So just how do Gravity causes it to fall through the penstock inside the dam. At the end of. water through the penstocks and using the power of that falling water to turn a The amount of power generated depends primarily on the discharge through the is water density (lbs/ft3, kg/m3) Q is discharge (ft3/s, m3/s), g is gravity (32 ft /s2, Use this information to write an equation for the relationship between energy. If you want to extract every last bit of energy from your microhydro system, three main Lower Penstock & Hydro Connection making electricity, the water will not be pressurized for other uses and gravity needs to take the water away freely.

In areas with very steep terrain, there may be no way to apply thrust blocking in the normal manner. You can change the angle with a king nipple similar to a hose barb and a short, high-pressure piece of rubber hose, or you can use two Correction may be unnecessary for hydro turbines that have a gang manifold at the end of the penstock or use valves and hoses to feed the individual nozzles.

### The Power of Water - Hydropower Plant Parts | HowStuffWorks

Some manifolds are hard-plumbed, and will likely need an angle correction where they meet the penstock. A cleanout valve at the end of the manifold may also be helpful for draining or flushing leaves and trapped sediment. The most visually impressive installations have the pipe exiting the ground at a If you keep your turbine out of the weather, it will last longer and need less service, especially the wound-field models.

Although the most common mount is a simple, 2- by 4-foot plywood, structure, built close to the water source, the most durable mounting platforms are sturdy plates on permanent concrete structures with the tail or waste water exiting the bottom or side, either into a wide opening or a drain pipe.

The drainpipe needs to be at least twice the diameter of the supply pipe, with a reasonably steep downward slope. An air vent in the tailbox will help prevent the tail water from sucking on the water running through the hydro, creating a power loss on an impulse turbine. Another popular hydro mounting method uses a modified gallon metal drum, with the turbine fastened to the drum top with bolts. The bottom third of the drum is secured into the creek bank with concrete or by loading the drum with rocks.

The middle third has a hole drilled out, which allows water discharge.

These drums will usually last about 10 to 15 years before they rust out. Alternatively, an up-ended culvert pipe that is 24 inches or larger can be used, though fabricating a top will be more difficult. This special-order item is more expensive, yet longer lasting, than plywood. Mounts can have more elaborate masonry spillways or even drains that feed to a decorative water feature in the yard.

Other times, the tail water can be used for a secondary purpose, such as filling a pond or irrigating a garden. Let your imagination be your guide, but remember that once you have extracted the energy for making electricity, the water will not be pressurized for other uses and gravity needs to take the water away freely. The final consideration for hydro mounting is protection for electrical portions of the control panel. Though rain needs to be kept out, the unit should not be so well sealed that condensation becomes a problem.

A roofed, three-walled structure for the turbine works great. One side is left open for easy access to the hydro plant. Although most permanent-magnet turbines are built for outdoor operation, they will last longer if protected from the elements. In terms of human resilience—an all-important factor to enable turbine maintenance—having a shelter makes repairs, flushing the penstock, and cleaning the turbine jets much more tolerable. Best Penstock Practices For penstocks, the rules are simple—straight-as-possible, round sweeps, and steady elevation declines.

Often times, site constraints make it necessary to break or bend the rules. You should do what you have to do, but know that your system will be more vulnerable to performance and maintenance issues. Any low spots in the pipeline, for example, could become sediment traps that will occasionally need to be blown out by opening the pipe at the bottom and letting it run full volume. High spots in the penstock will create air pockets that will need to be bled. Finally, any bend in the pipeline will mean greater resistance to flow and reduce the energy available.

Include a pressure gauge in the pipe on the uphill side of the lower shutoff valve to help diagnose problems. Hydropower plants are actually based on a rather simple concept -- water flowing through a dam turns a turbine, which turns a generator. Here are the basic components of a conventional hydropower plant: The shaft that connects the turbine and generator Dam - Most hydropower plants rely on a dam that holds back water, creating a large reservoir.

Intake - Gates on the dam open and gravity pulls the water through the penstock, a pipeline that leads to the turbine. Water builds up pressure as it flows through this pipe. Turbine - The water strikes and turns the large blades of a turbine, which is attached to a generator above it by way of a shaft. The most common type of turbine for hydropower plants is the Francis Turbine, which looks like a big disc with curved blades. Generators - As the turbine blades turn, so do a series of magnets inside the generator.

Giant magnets rotate past copper coils, producing alternating current AC by moving electrons. You'll learn more about how the generator works later. The Grand Coulee dam on the Columbia River in Washington is one of the largest dams in the world, with a capacity of more than 6, megawatts MW. In addition to very large plants in the western states, the United States has many smaller hydropower plants.

In there were 3, hydropower plants across the country, though by that number had fallen to 1, Since then, a number of these small plants have been restored; as ofthere were 1, hydro plants not including pumped storage in operation [ 5 ]. These plants account for only a tiny fraction of the dams that block and divert our rivers.

Converting moving water to electricity In order to generate electricity from the kinetic energy in moving water, the water has to move with sufficient speed and volume to spin a propeller-like device called a turbine, which in turn rotates a generator to generate electricity.

Roughly speaking, one gallon of water per second falling one hundred feet can generate one kilowatt of electricity. An opening in the dam uses gravity to drop water down a pipe called a penstock. The moving water causes the turbine to spin, which causes magnets inside a generator to rotate and create electricity. There are a variety of types of turbines used at hydropower facilities, and their use depends on the amount of hydraulic head vertical distance between the dam and the turbine at the plant.

The most common are Kaplan, Francis, and Pelton wheel designs. Some of these designs, called reaction and impulse wheels, use not just the kinetic force of the moving water but also the water pressure. The Kaplan turbine is similar to a boat propeller, with a runner the turning part of a turbine that has three to six blades, and can provide up to MW of power. The Kaplan turbine is differentiated from other kinds of hydropower turbines because its performance can be improved by changing the pitch of the blades.

The Francis turbine has a runner with nine or more fixed vanes. In this turbine design, which can be up to MW in size, the runner blades direct the water so that it moves in an axial flow [ 6 ].

The Pelton turbine consists of a set of specially shaped buckets that are mounted on the outside of a circular disc, making it look similar to a water wheel.

Pelton turbines are typically used in high hydraulic head sites and can be as large as MW. Generators at Hoover Dam.

## How Hydroelectric Energy Works

In this case, the volume and speed of water is not augmented by a dam. Instead, a run-of-river project spins the turbine blades by capturing the kinetic energy of the moving water in the river.

Hydropower projects that have dams can control when electricity is generated because the dams can control the timing and flow of the water reaching the turbines. Therefore these projects can choose to generate power when it is most needed and most valuable to the grid.

Because run-of-river projects do not store water behind dams, they have much less ability to control the amount and timing of when electricity is generated. Another type of hydropower technology is called pumped storage. In a pumped storage plant, water is pumped from a lower reservoir to a higher reservoir during off-peak times when electricity is relatively cheap, using electricity generated from other types of energy sources.

Pumping the water uphill creates the potential to generate hydropower later on. When the hydropower power is needed, it is released back into the lower reservoir through turbines. Inevitably, some power is lost, but pumped storage systems can be up to 80 percent efficient.

There is currently more than 90 GW of pumped storage capacity worldwide, with about 20 percent of that in the United States.

The need to create storage resources to capture and store for later use the generation from high penetrations of variable renewable energy e. Environmental and societal concerns While hydropower generation does not emit global warming gasses or other air pollutants, the construction and operation of hydropower projects can have environmental and societal consequences that greatly depend on where the project is located and how it is operated.

Dams that have flooded areas with live vegetation can emit methane, a powerful global warming gas, as that organic material decomposes. For example, the Tucurui dam in Brazil created a reservoir in the rainforest before clearing the trees.