WATERTURBINES

Introduction to Water Turbines
If you are lucky enough to have a water course across your property, such as a
stream, river, or if you are lucky enough to own an old water mill, water turbines
are an ideal solution for providing reliable long-term renewable energy. You can
easily calculate the available power at your site using the following equation:

Power (watts) = Head (m) x Flow (litres/sec) x 9.81 (gravitational constant ‘g’)

A typical water to wire efficiency is around 70%, so you should multiply the result
by 0.7 to get the actual amount of electricity that you can expect from the site.

Most sites vary considerably in flow between winter and summer, reflecting the
differences in rainfall. It is important to make sure that the flow is sufficient to run
the turbine, and if you wish extract maximum power from the turbine site, it is
often desirable to install two turbines, switching in the second machine, when the
water flow allows. Alternatively, a twin nozzle machine may be used, which
incorporates a valve to isolate the second nozzle when insufficient flow is
available to run both nozzles.

NET METERING

Water turbines are ideal for net-metering. You can sell your surplus energy to the
national grid, and get paid 7.9p/kWh. This means very short pay-back times
especially for DIY installations, and in all cases, the investment will be
PROFITABLE! There is also a ROC (Renewable Obligation Certificate) which
can be claimed - this is 4p/kWh, but it does involve some paperwork. Ofgen are
currently revising this, so hopefully things will become easier over the next year or
two. In fact, you can claim the 4p/kWh even if you use the electricity yourself! This
can make renewable energy very cost-effective.

High/Medium Head Turbine

These turbines are lightweight, and small in physical size, and yet able to supply
high quality electricity, regulated in terms of frequency and voltage by their own
internal voltage stabilisation circuitry. They are based on 'Turgo' runners, which
provide an ideal alternative for the Pelton wheel at lower heads. The medium
head turbines, for example, incorporate a ‘dump load’ ballast heating element in
the draught tube, which uses water-cooling to ensure that the load on the turbine
remains constant. The machines may be operated for years with minimal
maintenance, although it is necessary to apply grease to the bearings using the
grease cap a couple of times a month, to ensure a long life. By reducing the jet
diameter on these turbines, it is possible to operate them with heads of over
100m

Model No XJ14-02DCT4-Z Head 10-14
Metres Flow 2-4 Litres per second
200watts
220 volts 1500rpm Price £406

Model No XJ14-0.3DCT4-Z Head 12-14
Metres Flow 3-5 litres per second
300Watts
230 volts 1500rpm Price £485