Posts Tagged ‘Hydroelectricity’

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

December 14th, 2009 | admin

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