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Waterpowered systems have been used for centuries to remove heavy labor from the human race. In earliest times waterwheels were used to turn millstones to grind grains and for raising water from wells. Later, waterwheels were found on the banks of rivers where they supplied sawmills and textile factories with the unceasing rotary motion needed to power their processes.
In the 19th century the discover of steam power made the old waterwheels obsolete. With the invention of the turbine for generating electricity, the interest in water power systems was again revived. This led to large hydroelectric systems but also made smaller hydropower systems possible. The converting of waterpower into electricity through the use of personal hydroelectric sources has grown in popularity due to the ability of such a source to sustain the energy need of any household. With hundreds of thousands of untapped hydroelectric sites more and more people are seeking out the level of total independence offered by waterpower systems.
Today there are four main systems. Pelton turbines require very little flow to operate and can often operate from a small spring. They operate at their best with 50 feet or more of head and results in a jet of water that will spin the bladed runner close to generator speed without need for additional gearing. Cross-flow turbines are relatively new and do their best work when the head is larger than 3 feet. These units are easily made in a home machine shop and work great for smaller installations. Propeller turbines run effectively on low heads from 3 feet to 30 feet. The submerged propeller is moved by the dead weight of the water. These units only work well over a narrow range of speeds and may have problems compensating for flow changes. Francis turbines are very efficient at optimum flow but are easily damaged by cavitation and grit. With these units the runner is immersed into headwater, which is guided to the blades. Turgo turbines have brought recent improvements to the Pelton turbine due to their smaller size and ability to go faster. Kaplan turbines have automatically adjustable blades that can compensate for the flow change problems found with the propeller turbines.
Keep in mind when making a decision to use waterpower systems that the smaller the installation the higher the construction cost will be. It could take up to 20 years for a small installation to pay back the initial expense although rising fuel cost could shorten the pay back period.