PhD Thesis - Energy Systems Research Unit - University of Strathclyde

oth these feedstock supplies, however, poses a problem for this process, as it
requires a single daily input. If a continuous process is being used, the
feedstock produced is collected and stored to allow one input each day at a set
time. If a batch process is used, and there are enough fermenters to allow a
daily production of the feedstock, then this amount is input into the digester
each day. The process characteristics are defined, and the outputs and energy
use are calculated in the same manner as described in Section 6.2.
If there are not sufficient fermenters to allow a daily production of the
feedstock, the number of days each batch requires to run is determined, and the
number of fermenters available is divided by this number of days to determine
the fraction of the feedstock from one batch which would be available for input
to the digester each day. This amount of feedstock may then be input into the
digester each day for the number of days each batch requires to run. If further
feedstock is available, the process continues. If it is not available, the process
slows down as described in Section 6.2. The build-up period and options for
the use of the biogas are also dealt with as described in Section 6.2.
All the specific fuel production rates calculated using these procedures (i.e.
methanol, 95% methane), for each timestep, from each process, are added
together to make one production rate profile for each fuel type produced. The
relevant production rate graphs are given along with the ethanol production
graph and overall energy use graphs, and the relevant overall production and use
figures are also given. The maximum required storage is given for the
gasification process, and a second simulation period is, again, analysed, as
required, if there is a substantial amount of feedstock remaining at the end of the
simulation period. The procedures described in this section are shown in Figure
6.8.
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