PhD Thesis - Energy Systems Research Unit - University of Strathclyde

Various studies have been carried out into the extensive use of new and
renewable resources, to generate electricity, on a small scale, for rural
communities, grid-isolated islands and individual farms [17-25]. These studies
have generally been for autonomous systems, though some have used a grid
connection as a backup. Although the studies have different emphases, they all
recognise a few common and important points.
• To allow security of supply when considering intermittent sources,
demand and supply must be as well matched as possible, and this is
generally a function of climate. For example, in warm climates like that
of California, high demands are recorded during the day as air
conditioning units are run, and this matches the available solar energy
resource. The UK is not so fortunate, with little correlation between the
two main intermittent sources (wind and solar) and energy demand. A
further problem for the UK is the increased demand during the winter
months, mainly for heating, with a small increase in wind power and a
large reduction in solar power to meet that demand. Therefore, all
available supply sources should be considered in order to find the best
possible correlation between demand and supply.
• To allow security of supply, it is prudent to use as diverse a mix of
generation methods as is available, allowing the variable and
unpredictable nature of individual sources to be partially compensated
for.
• Where possible, energy limited sources should be used as spinning
reserve for times when the intermittent supply does not meet the
demand. If this type of spinning reserve is not available, the need for
adequate electricity storage was shown to be an important consideration,
especially in smaller scale projects. For some climates it may be
important to consider the need for inter-seasonal fuel storage or
increased generating capacity during the winter months.
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