Page 162 - Sustainability in the Process Industry Integration and Optimization

Fu r t h e r A p p l i c a t i o n s o f P r o c e s s I n t e g r a t i o n 139

• Calculate the emission levels (S C ) and limits (D C ),
i out,i j in,j
respectively, of the energy sources and demands.
• Plot the Demand CC with the energy quantity (D ) as the
j
horizontal axis and the emissions limit (D C ) as the
j in,j
vertical axis. Hence the slope of the CC at any given point
corresponds to the emissions factor (C ).
in,j
• Plot the Source Composite Curve in the same manner as with
the Demand Composite Curve, but use instead the quantities
S and S C . In this curve, the slope at any given point
i i out,j
corresponds to the emissions factor S C .
i out,j
• Superimpose the two CCs on the same graph.
• Shift the source CC horizontally to the right so that it does
not cross the demand CC. In final position, the former should
lie diagonally below and to the right of the latter. The two
curves must touch each other tangentially without crossing;
their point of contact is the Pinch point.
• Note the distance from the origin of the graph to the leftmost
end of the Source Composite Curve. This distance gives the
minimum amount of zero-carbon energy needed to meet the
system’s specified emissions limits.
• Finding the Pinch point yields valuable insights to decision
makers—in particular, it identifies the system bottleneck.
The “golden rule” of Pinch Analysis can then be applied to
the problem: in order to meet all the specified emission limits
for the system, the zero-carbon energy resource is supplied
only to those energy demands below the Pinch point. Any
allocation of this resource above the Pinch point will either
lead to an infeasible solution or require more zero-carbon
energy than the minimum quantity established by Pinch
Analysis.

6.4.5 Regional Resource Management
Regional Resource Management Composite Curve
A novel approach to regional resource management has been
developed that tackles simultaneously the two most important issues
with biomass supply chains: transportation and land use. The
biomass supply chain problem is complex because of the distributed
nature of biomass resources and their low energy density,
which necessitates large transportation capacities. Growing biomass
requires considerable land areas, often leading to competition with
food production. To address these problems, a two-level approach to
biomass supply chain synthesis—based on a novel Regional Energy
Clustering (REC) approach—was proposed by Lam et al. (2009). The