Introduction
The British Government
and the EU demands that the quantity electricity generated using fossil fuels
be greatly reduced. The "green" alternatives such as wind wave and
solar power are Dependant on climatic conditions and tidal power has great
difficulty in generating continually over a 24 hour period. This is a real
problem to the electricity supply companies who need to ensure that the demand
for electricity can always be met This is no difficulty at present, since the
quantity of "Green " electricity produced is not a significant
percentage of the total, but as the number of wind farms increase, this will change.
In many countries the majority of the power generation relies on steam
turbines. These are highly efficient BUT inflexible. Basically they have to be
kept spinning and they can not be quickly shut down or started.
A turbine is a rotary engine that extracts energy from a
fluid flow and converts it into useful work.
Hydro electricity a
reliable form of renewable energy. Water turbines are highly efficient and
easily controlled to provide power as and when it is needed. In addition,
currently the only system available to store large quantities of electrical
power, is pumped storage. This involves pumping water into a high level
reservoir. This can happen when the demand for electricity is low, at night
for-instance. When the demand is high the supply can be rapidly increased by
running the stored water through Turbines.
Turbines can be
divided into two basic basic types. These are Impulse Turbines and Reaction Turbines.
In these the whole of the available energy of
the water is converted to Kinetic Energy before the water acts on the moving
parts of the turbine. In this type of turbine the cups or wheel passages are
never entirely filled with water. To achieve this the turbine must be mounted
slightly above the tail race.
