Micro Hydro Generator - Water Baby

Hydro generator with temporary housing, a plastic container/bowl, and a 4" pipe sleeve and bubble wrap to protect the metal pipe section from frost damage.

The Water Baby micro hydro generator shown with the electrical junction box, the mounting frame on a temporary support, the pipe inlet with stopcock and pressure gauge. The Water Baby is available with 1-4 nozzle openings. This is a one-nozzle model, as I have very little water available.

To reduce cost without sacrificing cable thickness, I opted for earth ducting cable, and wrapped red tape around the positive cable, as there was no other colour choice.

Temporarily the generator is supported on a steel box on battens, to be replaced by a more permanent wooden stool type frame, with the four legs driven into the ground.

The pipe is removed in this shot, showing the nozzle end (usually held in with a grub screw), as well as a spare nozzle with a larger aperture. The generator is supplied with a number of nozzles, each with a different size opening, used according to how much water is available. The smallest nozzle will allow about 3 gpm through at a head of about 120+ feet, however, I have found that the smallest nozzle used with that head, produces no current at all. If the springs are gushing after a good downpour I have been able to go to the second biggest nozzle. With the new buffer tank I may be able to use the largest nozzle, when the available water is just below the quantity needed for the largest one.

The generator body is made of aluminium, and the nozzle holder/nozzle is brass, therefore there will be electrolytic corrosion where the two meet in the presence of water. You can't do anything about the water, as there will be some splash back from the turbine, but I stopped the corrosion by liberally coating the brass parts with Vaseline. When first installing the hydro I failed to do that, and after a few days of not changing the nozzle, the brass part was jammed solid in the hole, and I had to prize it out with a screw driver. With the Vaseline the corrosion has ceased.

The brass nozzle holder supplied with the generator has a standard thread for UK 15mm/1/2" compression plumbing fittings. I used a tap connector with a fibre washer, and 15mm copper pipe and ball valve. However, different brands of compression fittings can have different thread pitch, so it would be advisable to take the fitting to the plumber's merchant to try out.

The tail race is a tube I fabricated from sheet aluminium to fit the opening of the underside of the generator. The edges were riveted together and the lower edge snipped and bent in slightly to minimize splashing. Still to be done is a caulking seal around the top edge which would prevent any splash-back to seep into the timber frame. The tube is pinned to the inside edge of cross struts supporting the generator, i.e. is not directly connected to the generator.

The support frame is made of 1" x 4" rough-sawn soft wood, screwed together at the corners. Two boards are screwed across the top side of the frame, with a cutout for the 5 1/2" diameter opening on the underside of the generator. The generator is screwed to these boards, through holes provided in the corners of the housing flange. The long side boards are extended beyond the corner of the frame so that any loose cover placed over the generator would have support on the end where the electrical junction box is mounted on a vertical board.

This 1000 litre tank helps to buffer the flow of water to the hydro generator. If the flow rate of the springs is just below the amount necessary for a given size nozzle, the tank will allow the larger nozzle to be used for a while, until the tank is empty. As the spring continues to deliver almost as much as is passing through the nozzle, the water level in the tank is only going down very slowly. The difference in electrical current between using one nozzle size and the next is more than is lost by having to close off the generator briefly to fill up the tank (less than an hour at 4 gpm). This is especially critical when the flow is just not enough for the smallest usable nozzle. It means being able to run the hydro maybe 20 hours a day, instead of not at all.

The blue pipe is the overflow from the spring which supplies my household water, plus another spring in the vicinity. The white pipe delivers water from two further springs.

The tank was free from a local cheese factory. These tanks hold liquid food additives (rennet and food colouring in this case - there is a second tank further up) and may be available from other types of food precessing plants. They come on a palette base, and must be used with the supporting cage, as they are a bit too flimsy on their own and buckle (tried!). Taken apart for handling, the parts are easy enough to manoeuvre, even by one person. I managed to get all parts up a very steep hill on my own without difficulty.

Connecting up a 32mm pipe to the tank without cutting open the top to crawl inside to screw on the lock ring of a tank connector needed a little trickery and compromise. The tank outlet has a screw-top lid with a removable center to be able to attach a short flanged pipe (the flange is held by the edge of the lid). The tank connector would have been too bulky in the lid, and would prevent the lid from being screwed onto the tank outlet. I bought a waste pipe 40mm/32mm reducer compression fitting, sawed off the 40mm end just above the point where it reduces, leaving a flange which fitted into the lid ring (with a sealing washer). Into the 32mm end I fitted a flexible connector, as the outlet was facing a big tree. The compression waste fitting just about fits the 32mm alcathene pipe. A push-fit connector is too loose. You would think 32mm is 32mm, but in plumbing that does not seem to hold true, just as 40mm waste pipes are not compatible between different brands. After cutting off the 40mm end of the coupler, I discovered the a 40mm Osma brand waste pipe fits snuggly into the flanged pipe supplied with the tank (after cutting off the curved spout end). If you have wast pipe off-cuts it would be a cheaper and neater option than the reducer.

This silt trap is also the collection point for two springs (#1 on diagram - the thick pipe - the 'stream', and #2 through the small pipe). The s/s filter is a strainer from a catering tea urn. Any silt, floating or suspended debris is retained in the strainer. Any smaller, heavy particle (fine silt/clay particles) will further settle out in the outer tank. This works fairly well, but does require occasional emptying. One of the springs has another filtration system at source.

There are a number of small springs along the contour line (#2 on diagram). I chiseled a little channel along this line, slightly sloping down, and embedded a pipe into some earth at the end. This was expedient at the time, as my solar panels were producing very little electricity, but the open channel means a lot of silt and debris gets washed into the intake container, especially after a down pour. When the spring dry up, which they do after several weeks of no rain, I will cement the bottom of the channel, run a perforated pipe through it, and cover it over with geo textile, also cement the pipe into a small dam.

The source of this water is on my neighbour's land, so the intake is at the bottom of a steep little stream (#1 on diagram). The pipe is cemented into a small dam. When building the dam, I first built a temporary one with clay in front of the cemented one, so the water did not wash away the wet cement before it set.

Due to the steep open channel leading to this intake (#1), silt and debris is a problem. Here the pipe feeds into a container within the outer container. The inner one traps the heavier grit and silt, then the water overflows into the outer one. The edge of the inner container has a series of vertical cuts to form a comb type edge to filter out any floating and suspended particles. This works fairly well, but still requires periodic removal of silt/debris from trap. The next experiment will be a DIY version of an aqua sheer or coanda intake filter, which filters the water before it enters the collection tank. It is a grill made of closely spaced wires set at an angle. The water runs over the top and drops into the intake area, whilst debris is washed down the sloping wire to be dumped outside the intake container.

This spring also supplies domestic water, which is first stored in a 500 gallon tank a few feet below. When the tank is full, the pipe from the spring is removed from the tank and fed to the hydro system via another intake, spring #2 nearby. Without a washing machine and flush toilet, the 500 gallons last a fair time, and in the summer the reserve has taken me through all dry spells so far. When the hydro generator is needed most in the winter, the water is usually plentiful, and when the water in the tank is nearing the bottom, it only takes a few hours to fill it again, leaving the main spring flow for the hydro the rest of the time.

This is a filter which did not work. It was placed over the pipe outlet hole and is made of woven s/s wire. The debris gets sucked into the screen where the intricate surface traps everything. At times the whole filter was caked up with the kind of sludge seen at the top of the filter in this photograph. A better solution would be a piece of capped pipe with numerous small holes drilled into it, and the incoming water allowed to wash over the filter to rinse the debris off. The smoother surface would allow this.

This was another reasonably successful filter experiment. A piece of 40mm waste pipe with numerous small holes drilled into the side is inserted into a waste pipe tank connector, which is attached to the bucket inside-out. The pipe is not quite as high as the rim of the bucket. The water enters the bucket around the side, silt is deposited in the bucket and the water starts pouring through the holes into the central pipe, and down into the intake container below, preventing floating and suspended debris from entering. As the silt level rises, and holes get clogged up, the water can still escape over the top, and what little debris finds its way out will be caught by the next filter placed at the outlet of the next tank. Although it still requires emptying it needs relatively little attention.

Hydro diagram

Hydro diagram, new pipe runs

Spring intake diagram