Archive for the ‘Hydro Power’ category

The Pelton Turbine (Pelton water wheel): The Past and Future of Hydroelectric Power

December 14th, 2009

The world’s supply of fossil fuels such as coal and oil is rapidly depleting. At the same time, we are become more aware of the large toll that the use of these fossil fuels is taking on our environment. Not only do they contribute to increased pollution and carbon dioxide levels but mining practices required to tap these sources are often devastating.   As a result, the need for environmentally friendly, renewable power sources becomes more evident every day. One of the most exciting and widely used forms of alternate energy is hydroelectric power. Hydroelectric power is known to be a clean and renewable resource with many benefits.

From nearly the dawn of recorded time, mankind has sought to find ways to utilize the power of water. We have used it for travel, for processing our grain, and for sanitation.  The use of water wheels to generate primitive forms of hydroelectric power dates back to ancient civilizations in Greece and Rome. Since its inception, hydroelectric power has proven to be very valuable and modifications and improvements have continued throughout time. One pivotal improvement in hydroelectric technology came in the form of the Pelton wheel.

Pelton Water Wheel

Pelton Water Wheel

The Pelton wheel was invented by Lester Allen Pelton (1829-1908) during the 19th century in the United States. Pelton’s invention was brought about by a combination of necessity and luck as many important technological breakthroughs often are. It has been said that Pelton was driven to travel to the west in 1850 as a result of the booming gold rush.

In 1964, he became employed as a millwright in a busy town. At this time, the gold rush was taking a toll on the environment and resources such as firewood and water were running low. This was pivotal because at the same time the demand for power was increasing rapidly. Although many water wheels were in place, the water supply could not meet the demand for power. This combination drove Pelton to investigate a more efficient water wheel.

Written accounts say that Pelton was inspired to design the Pelton wheel when the water wheel he was working on malfunctioned. During the malfunction, the wheel was thrown off balance causing the incoming water to hit the cups on the wheel near the edge rather than in the center as it was designed to do. Remarkably, Pelton observed that the wheel actually began to spin faster. Pelton took note and began designing a prototype for what would come to be known as the Pelton wheel.

In 1878, he revealed his first prototype constructed from a bike wheel and tin cups. His design was slow to gain popularity but was patented in 1880 and gained a steady following thereafter1

The Pelton wheel, in general, operates in the same way as all hydroelectric turbines and water wheels. They work by capturing the energy generated by the flow of water. As water is pushed onto the blades or cups, force is generated. This force acts through distance and results in the transfer of energy.  There are two primary types of water turbines in use today, the reaction turbine and the impulse turbine. The Pelton wheel is an impulse type turbine.

The Pelton wheel, like all impulse turbines, operates using Newton’s second law to extract energy from the flow of a fluid jet. These traditional turbines have cups or buckets around the wheel collecting the water. Each cup represents an individual cup shape. The cups are not split in any way. In this type of wheel, a jet of water shoots in the cup hitting it directly in the center thus pushing the wheel.

Pelton Water Turbine

Pelton Water Turbine

However, the Pelton wheel differs from traditional impulse water turbines in one very important way. On the Pelton wheel, each of the cups is split down the middle, typically by a metal divider. The overall effect is that each cup appears to be comprised of two individual cups placed side by side rather than one. These cup pairs are located at every spoke on the wheel.

In this system, the jet of water is still directed at the center of the cup but is then split as a result of hitting the divider. In the traditional cup design, the impact of the water hitting the cup is wasted energy. In the Pelton wheel system, the forces of the water are balanced in the cup and the overall wheel. As a result, efficiency is greatly increased. Below is a graphic video illustrating the Pelton wheel.

The Pelton wheel revolutionized hydroelectric power generation by offering an innovative design. It is highly efficient when compared to the other impulse turbines of the past. Additionally, it requires significantly less water and can be used in areas with low water flow.

Pelton wheels come in all sizes. Sizes range from small, household sized units to multi-ton units. Therefore, they can be used in many locations. Industrial operations and individual consumers alike can benefit from their clean, efficient power generation.

Pelton wheels are most efficient when they are located in areas with a high head of water.  That is, an area where there is a large drop such as a waterfall, before the water enters the wheel. Although many consider this to be a disadvantage, it is really an efficiency issue rather than a deal breaker. Pelton wheels can in fact operate in areas with a lower head of water with reduced, but still acceptable, efficiency levels.

Pelton wheels saw their greatest success in the early 1900s. With the advent of the diesel engine, their popularity declined. By the 1950s, Pelton wheels were virtually replaced by diesel engines in most applications. Many examples of these now antique wheels can be seen throughout the United States and the world. Click Below to see video of the historical Ames Colorado Hydro Power Station.

Despite their historical decline in use, Pelton wheels are making a comeback. They are again being manufactured and distributed with great success. Ironically, we again find ourselves in a situation similar to that which brought about the invention of the Pelton wheel. Again our natural resources are overtaxed and our non-renewable resources are dwindling. We are just now beginning to realize, as Lester Pelton realized in 1878, that we must find alternative, renewable, clean, and environmentally friendly resources to meet our power needs. The Pelton wheel deserves not only respect for its history but also for its potential contribution in our search for renewable resources.

1.Lemelson-MIT Program. Lester Pelton. http://web.mit.edu/invent/iow/pelton.html

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Hydroelectric Turbines: Harnessing the Power of Water to Generate Energy

September 27th, 2009

As the world’s energy consumption explodes, no one can argue that there is a growing need to find an alternative to fossil fuels. The need for renewable, environmentally friendly power sources grows more apparent every day. Among the renewable resources being investigated and implemented is hydroelectric power. Hydroelectric power has proven to be a clean, viable renewable resource with many benefits.

Of all the renewable resources in the world, hydroelectric power is by far the most widely used. In fact, in 2005, an estimated 20% of the world’s electricity was supplied by hydroelectric power. That’s an impressive amount of power and should not be underestimated.

Hydroelectric Turbine (Water Turbine)

Hydroelectric Turbine (Water Turbine)

Hydroelectric power is generated through the use of a hydroelectric turbine. These turbines work by capturing the energy generated by the flow of water. As water is pushed onto the blades of the hydroelectric turbine, force is generated. This force acts through distance on the spinning turbine and results in a transfer of energy. Video below will give you a good understanding on how this happens.

There are two primary types of hydroelectric turbines in use today. Both types offer renewable, efficient sources of power but differ slightly in their function and use.

The majority of hydroelectric turbines in use are reaction turbines. This type is most commonly used in situations where there is a large volume of water passing consistently through the area; this is known as high flow. The reaction turbine does not require a high head of water. The water head simply refers to the height of the water level above the hydroelectric turbine. A low head means that the water has a small drop before entering the turbine. An excellent example of a high flow, low head area is a small dam on a fast moving river.

Reaction turbines operate as water runs from a tube through the turbine. As the water flows from the tube into the turbine, the water pressure is changed and this results in energy transfer. Due to the importance of water pressure in this process, the hydroelectric turbine must remain submerged at all times. This often requires that the turbine be encased in water if the water levels at the site are not consistent.

The second type of hydroelectric turbine is the impulse turbine. This turbine operates similar to a pinwheel. As water hits the blade of the turbine, known as a runner, the blade is pushed. Impulse turbines require conditions converse to the reaction turbine. These turbines are best suited to areas with a high head and low flow. Therefore, impulse hydroelectric turbines, while less common, fill a necessary niche that reaction turbines can not.

There are many benefits to using hydroelectric turbines. Potentially one of the greatest benefits is the very low environmental impact of hydroelectric power. Once a plant has been fully constructed, no direct waste is produced in the energy harnessing process. Additionally, the water used is virtually unaffected and remains clean with no byproduct after processing. Not only is it a very clean form of power, but it directly reduces our dependence on non-renewable sources such as fossil fuels.

Another important benefit is that hydroelectric turbines are designed to run smoothly for decades. They require very little maintenance throughout their life. Maintenance typically consists of minor welding jobs to replace worn parts and costly repairs are minimal.

It is also noteworthy that hydroelectric turbines produce power often more reliably than other sources that depend on the weather. That is, fluctuations in the weather that may impact power sources such as wind power or solar power often do not impact water flow. As a result, hydropower is considered by many to be a more reliable, preferable source of power.

As with any power source, there are drawbacks to be considered. The most universally addressed concern is that, despite the clean nature of hydropower, there is still an environmental impact. In order to harness the power of the water, it is often necessary to create a dam or other barrier to stop, contain, or slow the water. Concerns have been raised that damming the water can result in increased evaporation. Additionally, a dam could be potentially detrimental to wildlife in the area dependant on the water for migration. To counter this impact, most hydroelectric facilities now include what is known as a fish ladder. A fish ladder is a structure constructed around the dam that allows for fish and other wildlife to move around the dam unimpeded.

One very exciting aspect of hydropower is the advent of the hydroelectric turbine for home use. This is often referred to as a micro hydropower system. Now anyone with access to flowing water can utilize this remarkable energy source for themselves! With minimal investment or technical knowledge, you can easily incorporate a hydroelectric turbine system into your life to meet some, if not all, of your power needs. For example, a moderately sized stream with a waterfall could potentially provide enough energy for a small home. Imagine how amazing it would be to have all of your energy needs met by simply harnessing the power of the stream outside your home! Watch the below video from youtube about how a town in the United Kingdom is utilizing micro hydroelectric turbines.

The minimum requirements for installing a home hydroelectric turbine system are simple. Your stream or river must have a minimum of 20 gallons of flowing water per minute and a 3 foot fall. The GPM can be easily measured by creating a temporary blockage and measuring the amount of time it takes the water to fill a 5 gallon bucket. To make things even easier, most manufacturers will work with you to custom build a system to meet your needs.

Even if you don’t have a large stream or river, do not discount the usefulness of a micro hydroelectric turbine system. These systems can be used in conjunction with solar and wind systems to provide your power needs. In such a system, you will have power on sunny days, windy days, and even on rainy days when your stream flows strong. Some manufacturers are even beginning to produce small hydroelectric turbine systems for drainage and run-off ditches, so if you do not have a stream, you can still benefit from this power source.

With all of the benefits associated with hydroelectric power, the choice seems clear. Not only is it a clean, environmentally friendly renewable resource, but it is also relatively simple and cost effective. As the population continues to skyrocket, so to does our demand for fossil fuels. At the same time our resources are dwindling. Now is the time to consider a switch to renewable resources. Among these resources, hydroelectric power, provided through hydroelectric turbines is a forerunner that must be considered for both commercial and home use.

Hydropower: Explore the power of Water

June 7th, 2009

The 20th century is the century of fossil fuels and oil. It is a century of pollution, environmental destruction and irresponsibility. Now that we are in the 21st century, we can begin to think of what this century will be known as, and considering the push by the Obama Administration for green jobs, it could be the century of renewable energy.

One form of renewable energy that actual predates nearly all other forms of energy is hydropower. Hydropower has actually been around for centuries. In India, as well as Rome, mills were powered by water wheels for the production of everything from grain to timber. With the power of the water, usually a river, moving by the mill, the wheel outside the mill would be pushed, helping to create energy through pulleys and levers within the mill.1

These days, hydropower is used for much more than just power mills. In the 21st century, it is powering the homes of millions of people and helping our civilization move from one that used dirty coal and oil, to one that uses the clean and renewable energy that is all around us.

Hydropower Generator (Hydro Turbine)

Hydropower Generator (Hydro Turbine)

How Is It Generated?

Hydropower is actually generated quite simply. As long is there movement of water, it is possible to generate power because water is 500 times as dense as air. Even a slow stream will generate power as a result. When the water moves through a dame, or a confined space, it begins to rush faster as a result of more water going through a smaller space. When it does this, it turns turbines that then help to power a generator. The generator then sends power into batteries and convertors in order to send power out or store it.

Types of Hydropower

Hydropower, specifically for the generation of electricity, comes in many forms beyond just the dams we all know and recognize. There is of course the dams, but also tidal power and wave power 2.

Currently, hydroelectric power supplies 19 percent of the world’s energy, which amounts to nearly 715,000 megawatts 3. Most of this comes in the form of large dams, like the Three Gorges Dam in China and the Hoover Dam in the United States.

The great thing about producing hydroelectricity in this manner is that there is no carbon dioxide emissions, or any burning of fossil fuels. For a world that is getting warmer due to rising CO2 levels in the atmosphere, this is good new.

Tidal power is another method of hydroelectricity generation that has become very popular in France and Russia, as well as in Canada, which has the largest tides in the world at the Bay of Fundy. By harnessing the energy of the tides moving in and out of the bays or estuaries, it is possible to generate large amounts of energy. While it is predictable, this form of energy generation is not able to follow the changing in electrical demand like hydroelectricity from dams can.

Wave power can also be used to generate hydroelectricity. By harnessing the power from ocean surface wave motions, it is possible to generate much more electricity than can be achieved through tidal power. By having floating generates that are turned by the air that is displaced by waves in hollow concrete structures, it is possible to create this electricity. While it is still in its early stages, countries like the United Kingdom are jumping onto this new hydropower bandwagon. One prototype device located at Port Kembla in Australia is expected to create 500 megawatt hours of power per year 4.

Advantages of Hydropower

How Hydropower plants work

How Hydropower plants work

So, what exactly are the advantages to this form of power generation then? Well, there are three main advantages, all of which are incredibly important to the long-term survival of our civilization in many ways 5.

The first is economics. Unlike fossil fuels, where oil, coal and natural gas has to be taken out of the ground, water is all around us and whether we use it or not, it is moving by and creating energy. Hence, there is no cost of fuel with hydropower. The Three Gorges Dam for example will cover the costs of its construction in as little as five years of full generation.

As well, fossil-fuel fired plants require a lot of service and only last about 50 years. However, hydropower plants that were built 100 years ago are still in generation, making them much more cost effective. Dams and other hydropower plants also use less people on site, thereby lowering costs even more.

As has been mentioned, hydroelectric plants and dams do not burn fossil fuels and therefore do not contribute to greenhouse gases and climate change. The only greenhouse gases that are produced by the plant and dam are those that are emitted during its construction, which are easily offset within a few months of the dam or plant’s use.

Reservoirs crated by dams also help to bring in tourists. The Hoover Dam is one of the biggest tourist attractions in the United States, and many towns take advantage of the water sports made possible by dams, thereby contributing tourism dollars into the area. Some multi-use dams also install irrigation support to provide water supplies for farmers, and even help prevent floods downstream.

Who Generates The Most Power?

In terms of the generation of hydroelectric power, those countries with many rivers generally lead the way in power generation. China is the number one producer of hydropower in the world with 563 terawatt hours. While Brazil, Canada and the United States come in second, third and fourth. Of those countries, Brazil and Canada use hydropower to handle 85 and 61 percent of their power needs. Hydropower takes care of 17 and five percent of the power needs of China and the United States however.6 Norway on the other hand produces 135 terawatt hours of hydropower but it generates an astonishing 99 percent of its energy this way.

Ten Largest Dams On Earth 7

Name Country Year of completion Total Capacity (MW)
1 Three Gorges Dam China 2009 22,500
2 Itaipu Brazil/Paraguay 1984/1991/2003 14,000
3 Guri (Simón Bolívar) Venezuela 1986 10,200
4 Tucuruí Brazil 1984 8,370
5 Sayano Shushenskaya Russia 1985/1989 6,400
6 Krasnoyarskaya Russia 1972 6,000
7 Grand Coulee United States 1942/1980 6,809
8 Robert-Bourassa Quebec, Canada 1981 5,616
9 Churchill Falls Canada 1971 5,429
10 Longtan Dam China 2009 6,300

Conclusion

While solar and wind power can create more energy than hydropower can, they are still in their infancy in terms of development. Hydropower has existed for hundreds of years and is available anywhere that there is movement of water. With some countries like Norway and Brazil generating over half of their electricity this way, it is only a matter of time before other countries follow suit and begin to catch up.

It is ironic that to move into the future of energy, we have to look at the past, at something as basic as a watermill. Sometimes going retro is good, as it is with hydropower.

1. http://en.wikipedia.org/wiki/Hydropower#History

2. http://en.wikipedia.org/wiki/Hydropower#Modern_usage

3. http://en.wikipedia.org/wiki/Hydropower#Hydroelectric_power

4. http://en.wikipedia.org/wiki/Hydropower#Wave_power

5. http://en.wikipedia.org/wiki/Hydroelectricity#Advantages

6. http://en.wikipedia.org/wiki/Hydroelectricity#Countries_with_the_most_hydro-electric_capacity

7. http://en.wikipedia.org/wiki/List_of_the_largest_hydoelectric_power_stations