PhD Thesis - Energy Systems Research Unit - University of Strathclyde

ut with 30% less land being required in general. This is due, mainly, to the
higher yield of ethanol per hectare of land (despite the lower energy density of
ethanol), and the similar energy requirements for the fermentation process
compared with the transesterification process. This may make the production
and use of ethanol a more desirable option if there is a limited amount of land
available, and the fermentation process also requires less raw material import. It
is more common however, to have existing diesel generating plant in gridisolated
areas, which is often an important short-term consideration.
8.4 Case study Conclusions
The list of possible supply combinations given here is not meant to be
exhaustive, but has been used to show the versatility and usefulness of MERIT
for this type of analysis, and to show the way in which the program can be used
to aid informed decision-making. This study highlights the limitations of
intermittent supplies used on their own, and stresses the need for fuelled reserve,
storage and/or a good use for excess electricity. The use of potentially available
waste, energy crops, and derived fuels for spinning reserve is considered, and
there potential use in a 100% RE system is shown. The benefits of including
CHP production are emphasized, along with the importance of the heat to
electricity supply and demand balance, which can be gained through diversity of
supply and storage options.
As there is limited land available on this island, the simplest and best option
would appear to be the use of substantial wind power provision, converting any
excess electricity produced into hydrogen for use in vehicles, catalytic heaters
and fuel cells. This is the simplest option to run, requires the smallest land use,
and gives the least amount of losses. The storage requirement for hydrogen is
not excessive, and could be easily achieved using suitable underground tanks.
This option can also be supplemented by the use of constantly run biogas CHP
generating plant in order to solve a waste disposal problem if desired, while still
maintaining ease of operation.
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