innovation through composites


(micro hydro-electric)

For clients with a potential water supply, at Carbon Concepts we believe that a water turbine offers much more potential than a wind turbine for the following reasons
  • stable power supply
  • self regulating (as rivers go into spate, the head at weirs generally reduces, thereby dropping the turbine speed)
  • lower machine cost
  • generally lower installation costs
  • no complex control electronics
  • no over-speed protection
  • "invisible" installation
  • much lower mechanical risk
  • payback over 2 - 3 years rather than 20 - 30 for wind

We are looking at three types of turbine, covering applications for most hydro situations, initially up to 5 KW


For a client requiring 2 KW to offset the electrical energy use in a house or office, the water turbine will provide that power continuously, unless there is extreme spate or drought.

To provide this average power, how large a wind turbine do we need?  Well, based on the B&Q publicity for their Windsave wind turbine, the average wind speed is typically 4 m/s.  Most wind turbines are rated at 12 m/s, and the power is proportional to the cube of wind speed, so to provide an average of 5KW, the wind turbine has to be rated at 

(12 / 4)3 x 2 = 54 KW !

This would be a VERY expensive piece of equipment to install.


To get useful power out of a water source we need;

  • A head of water, that is a vertical drop, of a minimum of 1 m


  • a relatively fast flow (3 or 4 m/s)

  • in most cases, a sufficient volume of flow so that the turbine installation does not affect the river flow and upset the environment.

The technology is infinitely scaleable. The Hoover dam shown here is a little extreme, but does show that, given a sufficient head and flow, powers of 10s of megawatts are possible.

The graphs shown below indicate the potential power and required flow for a given head.


Photograph of Hoover Dam  



The illustration on the left shows our first water turbine.  It has a 110mm diameter turbine and is rated at 500 watts with a 1.5 metre supply head.

Although we intend to develop this into a production machine, we have intentionally started with a small turbine so that it can easily be transported for demonstration.  It uses the 200 watt generator shown in our site.

We hope to move rapidly to a 220mm turbine, which will produce 2 kw at 1.5m head, and 4 kw at 2.5m head.

The graphs presented below illustrate how the power and water flow vary with diameter and head.

For applications where there is a low head (in this case less than 1metre), but where there is plenty of flow, we have designed the unit shown on the right.  To draw this power from such a small head we have a 300mm diameter turbine which requires a flow of 240 litres per second.

If sufficient flow is available, this design can be used with larger heads and will produce considerable power.  For example, with a 3 m head, it should produce about 10kw.

The power output is very dependant on the turbine diameter and the available head.  It is proportional to the diameter2 and the head1.5.  The graph on the left illustrates some examples based on derivatives of our small turbine.

An important consideration is the water flow necessary to achieve maximum powe from the turbine.  The requirement can be quite high, and must be a reasonably small proportion of the total flow if secondary environmental problems are to be minimised.  The graph on the right gives an indication of the flows necessary for our turbines.


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