Hydro Energy using the Power of Water
In many ways, Hydro Energy is very similar to “Wind Energy” in that a renewable energy source, in this case “water”, is used to rotate a turbine generator to produce electricity.
Hydro Energy is the energy derived from the power of moving water. Today large hydro electric power plants generate about 15 percent of the world’s electricity by extracting the potential energy which comes from the vertical distance that water drops, called the “head”.
This stored potential energy is released as work because the water is in motion, and the best way to put large amounts of water in motion is to let gravity do the work. Then the most important element for the production of “Hydro Energy” is not the water itself, as within reason any liquid could be used, but “gravity” as it is gravity that makes the water move. Then we can correctly say that hydro energy is gravity powered energy as we are generating electricity from gravity.
Rivers and streams generate currents of water because the water in them is moving downhill, even if only slightly, flowing downwards by the pull of gravity.
Then clearly the water which is flowing downhill, being pulled by gravity, contains large amounts of kinetic energy that can be extracted and used by a water turbine or water wheel and even a small stream can produce enough kinetic energy to turn a wheel.
The kinetic energy produced by the moving water is converted into either mechanical energy to perform some work or directly into electrical energy by means of an electrical generator, and this then is the basic science behind Hydro Energy production.
Hydrokinetic Energy is a highly developed form of “alternative energy” that can also be classed as a “renewable energy source”, with the English word Hydro originating from the Greek word meaning “water”.
The energy from the Sun heats large masses of water such as the sea, oceans and lakes, turning it into water vapour which rises forming clouds high in the sky. The cold air above the clouds condenses this water vapour which then falls back to Earth as rain or snow in the hills and mountains.
This well known cycle keeps the mountain rivers and streams supplied with plenty of water. This cycle of evaporation and precipitation (rainfall, snow, drizzle, etc), is called the “water cycle”, and will keep on going forever as long as the sun shines, and all for free, that’s why hydro energy is a renewable energy source. But to use this renewable energy source to generate electricity we must first use its gravitational potential energy to spin a water turbine generator.
How does it work
We now know that hydro energy is the process of generating electricity from water which harness the power of the rivers and currents. But we can also use the power of stationary or slow-moving bodies of water to generate electricity by storing it in large dams. The gravitational potential energy that is stored in the water above the dams wall is released as it flows downwards through large pipes to the bottom of the dam.
As the water flows down these large pipes it passes through turbine blades at the base of the dam causing the blades of the turbine to rotate which produces electricity. Because of the great height of the water above the turbine, called the “head”, it will arrive at the turbines at a high speed and pressure which means that we can extract a great deal of energy from it generating more electricity.
Then there are different ways in which we can use “Hydro Energy” to produce mechanical or electrical power with the four common types of hydro energy sources being:
- Run of River – this is the cheapest and simplest form of hydro energy were an undershot waterwheel (or turbine) is placed directly into the natural flow of a fast-flowing river or stream. The water wheel is then rotated by the movement of the water flowing beneath it. Run of river hydro systems are commonly used to elevate water for the irrigation of surrounding farmland or to produce a mechanical power for grinding corn, etc. Minidams or weirs can also be built to increase or regulate the flow of water underneath the water wheel.
- Water Diversion – this is a low-head micro-hydro scheme which channels a portion of the rivers water down a man made canal, trough or aqueduct (called a penstock) to turn a waterwheel at the bottom. It may or may not need the use of a dam or weir to divert water away from its natural course and through the penstock which travels downhill using the force of gravity to feed an overshot waterwheel from above. The flow of the water and therefore its potential energy through the penstock design may be regulated by means of a sluice gate or water valve.
- Water Impoundment – this is a large man made system that uses a dam or weir to store the potential energy of large volumes of water in a lake or reservoir which can then be used when needed to generate electricity. Water impoundment systems are the typical hydro-electric power plants we see in mountainous areas and countries were high dams can be built and deep reservoirs can be maintained.
- Pumped Storage – pumped hydro storage facilities store energy by pumping water from a lower reservoir to an upper reservoir when the need for electricity is low such as during the night time. During periods of high electrical demand, the water is then released back to the lower reservoir via turbine generators to generate electricity.
Hydro Energy is a clean, green technology which produces no pollution. Unfortunately, most of the lakes and rivers that could easily be exploited have already been dammed, so the future of hydro energy lies in the development of less appealing sites. But hydro energy is more than just a clean source of electricity.
When dams are built, they create large bodies of water for fish and wildlife to survive. These reservoirs and lakes have several other advantages and uses. For example, they provide opportunities for outdoor activities such as sailing boats, swimming, fishing, or just enjoying the surrounding outdoors as well as using the stored water from the reservoirs for drinking and to grow crops.
The major benefit that all forms of hydro energy have is that they provide power without burning fossil fuels, but water power is not without its drawbacks and here are some of the advantages and disadvantages associated with hydro power.
Advantages of Hydro Energy
- Hydro energy is a clean and reliable renewable energy resource.
- Hydro energy is more reliable than wind, solar or wave energy.
- Micro-hydro systems produce virtually no waste, greenhouse gases or CO2 emissions.
- As long as the water is there in sufficient quantity, electricity can be generated constantly.
- Once the dam is built, the energy is virtually free.
- Water can be stored in a dam ready to cope with peaks in electrical demand simply by controlling the amount of water released.
- Hydro-electric power stations can increase to full power very quickly, unlike other power stations.
- Large and mega-dams have multiple uses and can create recreational lakes and areas where before there were none.
Disadvantages of Hydro Energy
- The Damming rivers and streams may change the natural waterways, diverting water from areas that depend on it.
- Damming rivers alters the spawning migration of fish and other wildlife.
- Dams in rivers changes the quality, quantity and even the temperature of the water that flows downstream, which can have an impact on plant life.
- Finding a suitable site to build can be difficult as the impact on residents or the environment may be unacceptable.
- Dams are very expensive to build.
- Large dams can only be used in a limited number of places such as those with large water supplies.
- The reservoirs created by large dams and mega-dams destroy local habitats. When the area is flooded, trees and other plant life is submerged, and any animal and human life living in the area must relocate or perish.
- Over time, dams may become unstable allowing them to self-destruct which can lead to serious flooding, including loss of life and property.
Can Hydro Meet Our Energy Needs
Hydro-electric power plants are big and powerful, but you can make your very own micro hydro system. All you need is a stream or a river with enough water running through it at sufficient flow or pressure.
You can set up a simple hydro power system using pipes and rocks that feeds water into turbines and generators to power your home. Just as you can with your solar and/or wind systems, you can design a system that is either grid connected with battery backup, or stand alone.
For example, a small turbine in a stream that flows at a rate of about 12 litres per second (about 200 gallons per minute) falling from a head of about 10 metres (30 feet) can generate around 1kW (1,000 watts) of electricity at any given time. This is more than enough to meet the basic needs of the average family home.
In fact, for rural or mountainous homes with no mains electricity connection, a good micro hydro system will generate a steady, more reliable electricity supply than other forms of renewable energy and possibly at a lower cost. Depending upon the type of system installed, the power can be used for lighting and electrical appliances and for heating and hot water other forms of renewable energy such as solar panels can be used.
In the next tutorial about Hydro Energy we will look at one of the oldest and easiest ways of extracting usable power from the water flowing in a river or stream, by using a Waterwheel. Although water wheels are often considered to be relics from the beginning of the industrial revolution, modern water wheels are not as primitive as those of the past and continue to be used for low-voltage electrical power generation in a small scale hydro power system.
For more information about “Hydro Energy” and how to generate your own electricity using the power of water, or obtain more hydro energy information about the various small scale hydro energy systems available, or to explore the advantages and disadvantages of hydro power, then Click Here to order your copy from Amazon today about small scale and low head hydro systems which can be used for generating electricity.