Water is an extremely powerful material, and although it is soft to the touch, it can erode mountains and the hardest rocks on earth. Using this power can be a tricky business, but if you are successful, you will have a dependable and reliable source of energy. Water can be used to generate electricity, pump water, do mechanical work, or even just store energy for later use.

When creating a system to generate electricity from water, you must examine the site where the system will be. First of all, what is the source of water? Is it a pond, river, creek, or spring? Each of these has a different approach.

Converting water flow to electricity depends on 3 main aspects of the water: the difference in elevation between the source and the generator (head), the volume of water available at any one moment (cross sectional area), and the speed in which the water is traveling (velocity). The power in kilowatts is equal to the head in feet multiplied by the velocity in feet per second multiplied by the cross-sectional area in square feet, all divided by 23. So, for a head of 10 ft, a velocity of 1.4 ft/sec, an area of 4.8 sf, the usable power output would be about 2.9Kw. This would be a rather large stream, flowing fairly fast.

Once you determine the water source and the amount of power available, you will want to choose a method of conversion. Turbines come in all shapes and sizes, depending on your head and velocity. Most come ready to attach to a generator, and some will come with the generator built in.

Converting to mechanical power is pretty much the same as converting to electricity, except that you don't need the electrical generator. Also, you will want a lower speed out of your turbine, and this is where the big water wheels of the old days come into play. They have a lot of torque, but at very low speeds, which makes them great for doing mechanical work, like milling grain, cutting wood, drilling, etc. Basically, you will need to gear the water wheel to your desired speed and rig up some attachment for the implement.

Pumping water using water is a very old art. Several low-tech approaches have been developed over the years, including the Archimedes spiral pump, the hydro ram, and the piston pump. Each has its advantages, depending on how much water you want to pump each day and how high you want to pump it.

The Archimedes spiral pump
The Archimedes spiral pump is probably the oldest form of pumping water, and it is not just powered by running water, it can be powered by humans, animals, or some sort of motor or engine. The concept is surprisingly simple. Take a flexible hose and create a spiral. The input is the outlet on the outside of the spiral, and the output is in the center. You will have to devise a way to rotate the spiral in the water, and a water-wheel type mechanism is the most simple approach. Water enters the outer ring, and as the spiral turns, the water is forced towards the center, compressing air that was also taken in with the water. The air/water combo builds a small pressure as it spirals inwards, and as is passes out of the spiral, it has enough pressure to be forced up hill. This system is limited to 150 feet of pumping elevation, but the volume is only limited by the size of your hose. Several such systems can pump over 4,000 gallons of aerated water a day! It is best used in a creek or river, although wind-powered models are often used in ponds for aeration.

The hydro ram
The hydro ram is a completely different animal altogether from the spiral pump. Although it is fairly simple as well, most people have a harder time visualizing its operation. Basically, the ram is placed at the bottom of a pipe with at least 20 feet of head. The water enters the ram through a check valve, and compresses a piston of air. The air compresses and then springs back, forcing the water out through 2 other check values. Not all of the water is pumped uphill, only about ¼ of the water entering the system gets pumped uphill, however, but that ¼ has a higher pressure, so depending on your head to begin with, a hydro ram can pump several times higher than the initial head. The volume again is limited by the size of the pipe and compression chamber.

Piston pumps
Piston pumps are the modern version of the ram pump, and instead of air, they use metal as the piston. They are powered by an engine or motor, but can also be powered by a creek, windmill, the sun, or any heat source. These simple compressors can be found in many applications and configurations. They can pump to very high elevations, as the metal does not compress or deform like in a hydro ram.

Water as a Battery
When water gains elevation, it also gains potential energy, so raised water can be used as a way to store energy. Consider this example: a windmill pumps water from a river at the base of a valley. The water gets pumped up to the top of the highest hill in view to a large storage pond. The water is then released slowly through a pipe in the storage pond that travels back down to the river. At some point before the pipe enters the river, a water turbine is placed in the pipe and electricity is generated. This simple approach is used by some of the largest hydro-power facilities in the world. Many variations are available on this system. The attractive aspect of the system is that is it fairly low-tech, does not require chemical batteries, can be repaired and maintained easily, and should have a long lifetime. The downsides are that it requires a HUGE amount of water to actually power this system. You would need a decent raise in elevation and a decent amount of storage on the hill, making it somewhat prohibitive for a home-built system. Also, you need just the right type of property to make it work.

By working with water, we can take advantage of its inherent power and forces. This takes careful planning and skills, but the benefits are numerous.