CFP CCFP - CFP *
4.1 Construction of Regional Resources Management Composite Curve
The RMC has been developed by the PhD candidate (Lam et al., 2009a, 2009b; Lam et al., 2010a) to graphically represent the relationship between the land use and the generation and consumption of energy. The RMC is a graphical tool that can be used to support the decision-making process in regional resource management, as shown in the next sections. The principle idea of a Grand Composite Curve (Linnhoff and Townsend, 1983) has been exploited and translated to the problem of regional resource management. For regional resource management, the x-axis represents the energy supply/demand profile (TJ/y) and the y-axis represents the cumulative land area for the studied region. The pockets represent the supply-demand among the zones.
The procedure for the RMC construction is:
1. Construct a Regional Energy Cascade Analysis for biomass transfer between zones.
i) Create a sequence in the descending order for cluster imbalance. Start with zone with the largest energy surplus.
ii) Calculate the energy land use rate, L for each zone.
0 considered in the energy supply chain targeting.
iii) Sequence the zones within the cluster by descending value of Li.
iv) Cascade the surplus or deficit value of each zone by using bottom-up or top-down direction. Each zone size becomes a cumulative area interval for the plot.
The cascade is just a cumulative tool and it doesn’t reflect to the particular links between the clusters.
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2. Plot the RMC with the cumulative area (km2) as y-axis and the accumulated energy balance (TJ/y) on the x- axis. The coordinates for the points in the RMC represent the accumulated area and the surplus/deficit value from cascade interval. Figure 4.1 shows two options of presenting the RMC. The energy cascading can be performed
(a) Bottom-up cascaded RMC (b) Top-down cascaded RMC
Figure 4.1. Constuction of the RMC (Lam et al., 2010c)
RMC puts together the information about energy surpluses/deficits as well as land use, allowing for a direct assessment of the trade-off between them. The curve from Point A to E in Figure 4.1 represents Cluster 1. From the left-hand turning Point E, to Point H the curve represents Cluster 2. The intra-cluster energy transfer (supply-demand relationships) between the zones is represented by the shaded areas or Pockets B-C-D-E, F-G-H.
For the bottom-top cascaded RMC, as shown in Figure 4.1 (a), the zones with positive slope supply biomass to the demanding zones which are with the negative slope as
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direction shown by arrows in the figure. Since the zone areas are fixed, a steeper positive slope means less net energy is available from a zone. A steeper negative slope means the net energy demand for the zone is smaller. The parts of the RMC plotted on the right hand side of the y-axis represent the activities within the studied region.
Based on the RMC several options are possible to tackle the problem of resources management in a region. They are mainly based on the issue of energy surplus and deficit and the land use management.
After the bottom-up cascaded RMC has been constructed there are 5 basic rules to be applied while manipulating regional resources such as land and the surplus energy.
These rules give a clear overview picture and useful hints to the planner on how to manage regional resources with a single graph.
Rule 1: If m TJ/y of surplus energy is being planned for export from Zone i , the curve of Zone i and all of the curves after that are shifted together to the left horizontally by m TJ/y
Rule 2: If an extra land of n km2 from Zone i is being used for other purposes instead of energy production the segment given by n km2 is cutting out and shifting the curves above it to the left.
Rule 3: If p TJ/y of external energy is being planned for import to Zone i , the curve of Zone i and all of the curves after that are shifted together to the right horizontally by p TJ/y
Rule 4: If the production rate for energy crops in Zone i is increasing or the energy demand is decreasing the slope of the curve is decreased.
Rule 5: If the production rate for energy crops in Zone i is decreasing or the energy demand is increasing the slope of the curve is increased.
74 4.2 Demonstration Case Study
A demonstration case study is used to illustrate how to implement the suggested rules.
The information about the potential biomass sources, the area and location for a particular zone are shown in Table 4.1. The utilisation percentage of the biomass is set as 60 % of the theoretical potential bioenergy which is the product of potential biomass (t/y) and its heating value (MJ/kg). The study is focusing on the biomass production and its transportation network from the source point to the demand site.
Table 4.1. Regional data for demonstration case study for RMC case study Zone Area Location Potential
Biomass
Heating value
Energy Supply
Energy Demand (km2) (km, km) (t/y) (MJ/kg) (TJ/y) (TJ/y)
1 30 (0, 0) 1150 18.5 12.76 11.76
2 20 (8, 1) 1680 18 18.14 21.89
3 25 (8, 5) 1360 17.3 14.12 12.67
4 20 (10, 4) 940 6.4 3.61 1.61
5 15 (12, 10) 2420 10.5 15.25 19.75
6 30 (14, 9) 1080 15.5 10.04 9.04
7 25 (18, 10) 980 16.8 9.88 7.63
The case study considers the local community in the studied region as the energy consumers. The biomass surplus is transported from the collection point nearby the sourcing location to the biomass energy conversion plant to support the regional energy demand. A co-generation power plant with biofuel boilers is used for this purpose.
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The optimal biomass transfer flows estimated by REC algorithm are shown in Figure 4.2 The biomass transfer is indicated by the corresponding flow magnitudes and the arrows indicate the transfer directions from the energy surplus zones to deficit zones. The locations of the centroids are represented by the “●” symbols. It can be seen that the region is partitioned into 2 clusters. Zones 1, 2, 3, and 4 form Cluster 1. Zones 5, 6, and 7 are grouped into Cluster 2.
Zone 1 Zone 2 0
Zone 3
Zone 4
Zone 6
Zone 5 Zone 7
x (km) y (km)
2.25 TJ/y
1.0TJ/y 0.75 TJ/y
1.25 TJ/y 1.5TJ/y
1.0 tJ/y Cluster 1
Cluster 2
Figure 4.2 Optimal biomass transfer flows resulting from the REC algorithm (Lam et al., 2010c)
The RMC construction is illustrated in Table 4.2. The data is arranged according to the procedure described in the Section 4.1. This data is then plotted in a RMC (Figure 4.3).
The RMC displays the information about energy surpluses/deficits as well as land use, allowing assessing the trade-off between them directly.
76 Table 4.2: Data for RMC construction
0
Figure 4.3 Energy and land use management with the RMC (Lam et al., 2010c)
The first interval has a surplus of 1.0 TJ/y, which is cascaded to the next interval. This cascaded result is reflected as point L on the RMC on the right hand side. The second interval and the third interval have also 1.50 TJ/y and 2.00 TJ/y, which accumulate to 4.50 TJ/y (Point N) to be cascaded further. In the forth interval, the zone has a deficit of
Cluster Zone, Z Area (km2) Surplus/ Deficit
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3.75 TJ/y, which leaves 0.75 TJ/y (Point O) to be cascaded to the next interval and so on. The RMC also shows that, the region is divided into 2 clusters. Each left-hand turning point (could be also called a cluster pinch) indicates the start of a new cluster.
The cluster will have surplus of biomass energy if the last point is plotted right side of the starting point otherwise the cluster will have energy deficit. The energy balance for the whole region is a deficit 0.50 TJ/y which represented by Point S that plotted on the left hand side of the y-axis. Figure 4.3 also indicates the size of each cluster.
There are several possible options to tackle the energy-land trade-off problem. The segment between Points J and K in Figure 4.3 represents the surplus in Cluster 1.
Three options can be considered to deal with this surplus:
i. Export 0.75 TJ/y of energy from Zone 1 to energy market. Figure 4.4 shows that, the whole composite profile is moved to the left 0.75 TJ/y (Rule 1). The Point J’ is plotted on the left hand side of y-axis; this means that 0.75 TJ/y is transported to the market.
Cumulative energy balance (TJ/y) Cumulative Area (km2)
K
-1 J’ 0 J 1 2 3 4 5 K’
50 100 200
150
Figure 4.4 Modification of the RMC if the surplus in Cluster 1 is exported to energy market (Lam et al., 2010c)
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ii. Use the extra land of 22.5 km2 from Zone 1 for other purposes instead of energy production. As shown in Figure 4.5 the new point, K’ is created by cutting out the segment 22.5 km2 and shifting the remaining part of the RMC 0.75 TJ/y to the left.
(Rule 2).
Cumulative energy balance (TJ/y) Cumulative Area (km2)
K’ K
Original curve 22.5 km2 0.75 TJ/y
-1 0 1 2 3 4 5
50 100 20 0 15 0
Figure 4.5. Modification of the RMC if a certain area in Zone 1 is used for other purposes (Lam et al., 2010c)
Another option is using 16.67 km2 of area from Zone 4. As illustrated in Figure 4.6 Point T is shifted by 0.75 TJ/y to T’. A gap of 16.67 km2 area appears on the resulting RMC.
79 Cumulative energy balance (TJ/y) Cumulative Area (km2)
T M T’
-1 0 1 2 3 4 5
50 100 20 0 15 0
Figure 4.6 Modification of the RMC if a certain area in Zone 4 is used for other purposes (Lam et al., 2010c)
iii. Transfer 0.75 TJ/y of energy to Cluster 2. This situation is presented by Figure 4.7.
Firstly the original RMC in Fig. 4 moved to the left. The intermediate step is resulting in Figure 4.4. The exported energy (Segment J’K’) is transferred to Cluster 2 (as shown by the arrow). As a result, the segment of 22.5 km2 land is cut out (Rule 2) and the point after O is horizontally moved 0.75 TJ/y to the right (Rule 3)
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Cumulative energy balance (TJ/y) Cumulative Area (km2)
K’
0.75TJ/y
-1 J’ 0 1 2 3 4 5 50
100 20 0 15 0
O’
Figure 4.7 Modification of the RMC if the surplus in Cluster 1 is transferred to Cluster 2 (Lam et al., 2010c)
For the deficit case in Figure 4.3, the energy demand can be satisfied by
i. Import 1.25 TJ/y from the energy market. Figure 4.8 shows that after received the import, the pocket for Cluster 2 has been expended by moving 1.25 TJ/y to the right after Point O (Rule 2).
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Cumulative energy balance (TJ/y) Cumulative Area (km2)
O’
O
1.25TJ/y
-1 0 1 2 3 4 5
50 100
20 0 15 0
Figure 4.8 Modification of the RMC if a certain amount of energy is imported to fulfill the demand in Cluster 2 (Lam et al., 2010c)
ii. Increase the biomass production rate in the Cluster 2 (Rule 4) , e.g.:
- Convert certain areas of land from other applications to energy crops.
- Grow other type of energy crops with higher yield.
- Increase the share of agriculture residues into energy sources, for example use straw for energy production instead of using it for animal feed.
The effect of these changes decreased the slope of OP and PQ to OQ’ in Figure 4.9
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Cumulative energy balance (TJ/y) Cumulative Area (km2)
Q’
O
Q
-1 0 1 2 3 4 5
50 100 20 0 15 0
P Slope OQ’ = 9.4 Slope PQ = 11.1
Slope OP = 15.0
Figure 4.9 Modification of the RMC if the biomass production rate in the Cluster 2 is increased (Lam et al., 2010c)
iii. Reduce the energy demand in Cluster 2 by improving the efficiency of energy conversion technologies (Rule 5). The slope of QS’ increased as shown in Figure 4.10
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Cumulative energy balance (TJ/y) Cumulative Area (km2)
Q
S S’
-1 0 1 2 3 4 5
50 100 20 0 15
0 Slope SQ = 5.6
Slope S’Q = 7.7
Figure 4.10 Modification of the RMC if the energy demand in the Cluster 2 is reduced (Lam et al., 2010c)