Memorandum submitted by Dr Stan Jones
The practical problems pertaining to any non-controllable,
unpredictable electricity source has to be clearly understood
in terms of the reliability and integrity of the supply to the
end user. Wave and tidal electricity sources are subject to uncontrollable
energy input, hence electrical output. Statistically the maximum
and minimum generation can be predicted under various circumstances.
Only the minimum guaranteed output can be used in any calculation
of the integrating of supply to the consumer. The excess actual
generation over this minimum will be effective in climate terms
in displacing conventional fuel consumed and therefore unwanted
gas release, but will not reduce the need for totally controllable
generating plant or stored energy to be available to make up the
This means that for every KW of nominal power
installed of wave or tidal electrical generation (1-min) KW of
storage or backup plant has to be installed. Since the accepted
requirement would be to meet the maximum demand on a still winter's
day, this backup generation/storage would, for the most time,
be idle, or at best cover for breakdown of conventional plant
at other times.
The installed cost of wave and tidal power therefore
has to include the cost of this necessary backup generation or
storage. The short term excess of generating capacity today will
mitigate against this requirement, but as this excess capacity
is progressively de-commissioned, as too costly or aged, the true
cost of the necessary backup will become apparent. Clearly the
larger the fraction of electrical generation which is of this
"unreliable" nature, the more this backup will be apparent
with ultimately a large amount of conventional generators lying
idle for long periods.
The higher the statistical minimum can be pushed,
the more pumped storage and other storage techniques can be utilised
and the more demand/generation can be averaged by geographic dispersion
(eg Link to France) the less generation backup will be needed.
As wave and tidal power is comparatively very
expensive in its own right, the addition of allocating backup
to this cost will considerably widen the difference.
The above describes the "steady state"
problem of integrating non-guaranteed electricity generation to
the system. There are a number of dynamic problems which I presume
will be covered by others.
R&D into improving the reliability of output
over a wide range of input energy, cost-effective storage and
cost effective backup (such as very low capital cost coppiced
wood burning generators where fuel storage and continuous running
could be a problemmaking them suitable for peak looping
backup), would clearly improve the situation.
7 February 2001