Introduction to Water Turbines:
Does your property have a water course crossing it, a stream or river. Do you own an old water mill?
Lucky you, in effect this is ‘untapped energy’ waiting to be harnessed – Liquid Gold for you!
Water turbines/ hydroelectric turbines are the ideal method to provide reliable renewable energy on a long term basis.
The available power at your proposed site is simple to calculate using this equation:
Power (watts) = Head (m) x Flow (litres/sec) x 9.81 (gravitational constant ‘g’)
A typical efficiency of water to wire is around 70%, you should therefore multiply the result by 0.7 giving the actual amount of electricity that you could expect from your proposed hydro site.
The flow rate does vary by a large factor seasonally, between winter and summer, depending upon rainfall. you must ensure that there will be sufficient flow to run your proposed turbine. Often it is necessary to install two turbines thereby extracting the maximum power from the site. When the water flow allows the second turbine is switched in. Alternatively rather than having two turbines you could use a twin nozzle turbine. A Twin nozzle turbine incorporates a valve that isolates the second nozzle when the flow is insufficient for both of the nozzles to be in use simultaneously.
Any energy surplus could be sold to the UK mains. You currently get paid 7.6p/kWh ( 21/06/2006 – Subject to revision or updates). This gives a relatively short pay-back time for a DIY installations. Your investment should be PROFITABLE anyway! A ROC (Renewable Obligation Certificate) may be claimed – currently 4p/kWh, Paperwork will need to be completed to claim. Often looking at this and ‘maybe’ this will become easier in the future.
High and Medium Head Turbines
These turbines are light, small in size, but they can supply high quality electricity. They are regulated, frequency and voltage wise, by internal voltage stabilization circuitry. Based on ‘Turgo’ runners, thereby providing the ideal alternative to a Pelton wheel at lower heads.
Medium head turbines, incorporate a ‘dump load’ ballast heating element in their draught tube. This uses water-cooling making sure that there is constant load on the turbine . These turbines could be operated for years requiring only a small amount of maintenance. However a couple of times a month it is necessary to apply grease to the bearings via the grease cap this minimal maintenance should ensure longevity. If the jet diameter is made smaller on these turbines, it is possible to operate them with a head in excess of 100m