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Ibasei's Cappa provides hydroelectricity on a small scale


December 12, 2012

The Cappa compact hydropower generator can deliver 250 W of electricity

The Cappa compact hydropower generator can deliver 250 W of electricity

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Despite being the most widely used form of renewable energy worldwide, hydroelectricity is generally reserved for large-scale commercial installations built around massive dams. Japanese company Ibasei has shrunk things down and removed the need to build a dam with its Cappa compact hydropower generator – a system that's designed to be installed along a river or waterway.

The basic design of the Cappa is nothing new – blades rotate as the water flows through the unit, which drives a turbine to generate electricity. However, the unit is encased in a special diffuser that is designed to increase the velocity of the water at the point where it passes over the blades, thereby increasing the unit’s electrical output.

A company spokesman tells DigInfo that a water flow of 2 m/s (6.5 ft/s) will see one unit produce 250 W of electricity, while five units together will generate about 1 kW, taking control losses into account. The unit produces 100 V AC electricity at 50/60 Hz, so it can be used to power appliances around the (Japanese) home. The unit itself is also 100 percent recyclable and has an uptime of virtually 100 percent.

While you’d need quite a few of these things to completely power the average household – and I don’t know a lot of people with steadily flowing rivers running through their backyards, Ibasei anticipates the device could come in handy for providing power to remote communities and tourist attractions and in the event of natural disasters – floods in particular seem like a good fit for the technology.

While larger blades have the potential to deliver more power, their optimum size is determined by the size, width and speed of the river in which they are placed. For this reason, Ibasei would like to survey each river in which a unit is to be placed to customize a system for each customer.

The company is currently in the final development and testing stage and hopes to have the Cappa available for purchase in 2013. The 250 W model is expected to be priced at around the cost of a compact car.

The Cappa is explained in the video below.

Source: DigInfo TV

About the Author
Darren Quick Darren's love of technology started in primary school with a Nintendo Game & Watch Donkey Kong (still functioning) and a Commodore VIC 20 computer (not still functioning). In high school he upgraded to a 286 PC, and he's been following Moore's law ever since. This love of technology continued through a number of university courses and crappy jobs until 2008, when his interests found a home at Gizmag. All articles by Darren Quick

why can't someone invent a tiny self contained hydro gen into new housing and buildings. something that can fit into water supply and waste lines? makes sense to me...


Most likely uses would be remote installations for sensor platforms and such. It's not a huge amount of power for human usage but you could run low power electronics for all sorts of things. Or it could slowly and constantly charge more power hungry equipment if it didn't need to be used constantly. Aerial drones that could remain charging most of the time and had multiple copies with similar power stations across a wide area could cover remote territory, performing tasks like search and rescue and even relaying small payloads like emergency provisions to people in the wilderness until rescuers can get there.

It is important to remember that a "useful" amount of power can be different depending on who or what is using it and how practical other forms of power are in the context.

Snake Oil Baron

250 watts for the price of a compact car sounds like a rip off to me.


The price of a compact car yet will be completely taken out by the first tree branch that is on that river...That's an expensive risk.


Most rivers/streams around here are not pristine but loaded with twigs, and other floating and suspended debris. These would easily jam the impeller. Even an upstream screen would clog pretty quickly. What about feasibility in colder climates, where icing would be an issue?


No worries about fish? No screen-how will it stop debris from clogging it? Way too expensive right now. Good idea though-work out the kinks. Adding a jacuzzi type shell might propel the water even faster for more power. Maybe horizontal blades that flip would hurt fish less.


Talk about reinventing the wheel! Water power was optimised in the 19th century with overshot water wheels reaching >90% efficiency. They dont clog, are almost fit&forget reliability and are simple and cheap to make. Hi-power fixed magnet generators which operate at low RPM that can turn this motive power into electricity.

This little thing is way too expensive, will clog easily and because it has gears turning 90 degrees in it will wear out.

Another solution to a problem which does not exist.

Dirk Scott

I like the design and could see these powering a house. Unlike a high pressure design, it could be used on a property in series. In other words you could put a bunch of them on the same property. You would just have to put enough space between them to allow the water to gain speed again. Pricing seems to be a problem in this article. They should have put out a number, the whole "compact car" thing lets a very large number appear in my head..... The assembly holding the turbine in the video is a bad design. They should have dock floats attached so the turbine will stay at the same height as the river as it rides and falls. With feet so it cannot bottom out. The whole thing tied off to post besides the river with cable.

overengineered and overpriced is no way to advance remote energy generation ...

if this is the best the green energy movement can come up with then we need a new green energy movement ...

these folks offer a 1300 watt unit for $1475 ...

and "speeding" up the water flow doesn't "add" power ... the energy contained in flowing water can't be "increased" it can only be extracted ...

Jeffrey Carlson

Agree with above comments re debris and price- a 'small car' price is vastly excessive for something that is technologically simpler than the average modern turbocharger.

In the UK the best small hydro plants seem to be the ones that use weirs, with fish bypass, and which take the form of a worm drive. As the water isn't guided into a casing there is far less potential for debris to get stuck in it.


It would not be too difficult to keep debris out by building a screen several meters upstream but the only advantage it provides over a undershot waterwheel is that it is easier to conceal.


Because few have 5mph water to work with and because of debris this unit won't be worth much except in extremely rare cases.

One can just put a flat pitched sailboat prop on a shaft and gear it up to a generator and do far better at a fraction of the price and work in 2-3mph water. BTDT


100 volts? why not 120v our appliances are designed for? Will draw excessive current.


so let me get this right you are going to charge the price of a compact car for that thing? to power 2 and a half 100watt light bulbs, good luck with that. i could make my own for less then $500.00 US. lol and oh by the way your design is completely wrong. i have designed same thing about the same size but delivers over 1,000 watts with same water flow as yours maintaining the same price tag as mentioned above. Regards, Freelance Eng.

Dave Hargraves

SKipJ. Japan runs on 100v not 110v.


for about $1000 you can buy a windmill that puts out 1KW...and build your own tower. 4x the power, although it varies. and you don't have to buy a car. if the price for 250 wh was $ would be worth it.


While that old waterwheel does get rid of all the real world issues of things that lacks the geewizz factor. it ignores the desire to pay 200 times the price to get a decimal point or 2 of " improvenent." that is of course a fools way and narrow view of efficiency. but i digress....venturi...its a stupid venturi. nothing new here except its less than the ramturbine where altitude is part of the equation. a float and a car alternator on a paddle wheel will get you 100amps of 12 volt. and you Could blow 3,4 hundred $$ on it. run the camp. charge batteries at the compound. power the radio shack...things an off the gridder might want help with.

Walt Stawicki

The Ampair UW100 has been around for many years and is a proven reliable device, no silly augmentor, just a roto spinning in a water flow. See

I don't know why people keep designing turbines, both water and air powered, with augmentors/diffusers, there's just no point and the extra complexity, materials cost and weight (a prob for wind turbines at least) outweigh any small increase in output. It seems that way too many engineers still have no practical experience or even common sense...

Mr T

They should put a few of these at the bottom of toilets and unrinal troughs at stadiums. During baseball games, football or concerts they could probably power the bathroom lights.

Layne Nelson
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