8. ENERGY SECURITY
8.2. Energy security in a Brazilian context
8.2.4. Electricity supply constraints imposed by transmission
Since 1999, Brazil has experienced two large scale blackouts.8 In both cases the most probable cause was poor maintenance and the high com-plexity of the transmission system. Also, during the 2001 electricity crisis, bottlenecks in the trans-mission network exacerbated the shortages. The South and North regions had an abundance of hydropower that could have been transferred to the regions experiencing shortages, had transmission capacity been available.
The Brazilian electric system has interconnec-tions between the extreme north and the most populated areas in the south, as well as between the cities along the coast and those in the west, including a small share of the Amazon jungle (see Fig. 8.6). In principle, such a huge interconnected system should allow the transfer of electricity among the South, Southeast–Midwest, Northeast and North regions, and over the 3000 km distances
in a straight line. In practice there are constraints imposed by the maximum amount of electricity that can be transferred by the existing transmission network (see Table 8.1). The strongest link connects the South and the Southeast–Midwest subsystems.
The weakest link connects the Southeast–Midwest region with the North–Northeast subsystem. A transfer of up to 1962 MW on average was performed between the South and Southeast–
Midwest subsystems (see Table 8.1) in an effort to mitigate the electricity shortage.
Table 8.2 lists transmission capacities available to feed the Southeast–Midwest electrical subsystem in periods of electricity shortage. In 2001, trans-mission capacity from the South to the Southeast–
Midwest region was limited to 3200 MW. The maximum transference for the Southeast–Midwest region was limited to 6600 MW, including the electricity delivered by the Itaipu binational plant, which shares the same line used to bring electricity from the South region. Itaipu is assumed by the National System Operator (NSO) to be able to produce 10 000 MW, of which 4500 MW were transferred using the line shared by electricity transmitted from the South region. Thus, it is possible to infer that maximum transmission from the South region to the Southeast–Midwest region was limited to 2100 (6600 – 4500) MW, very near the maximum value observed in Table 8.1.
As noted in Table 8.2, Government plans presented at the end of 2001 [8.23] foresaw the necessity of improving transmission capacities for the period starting in April 2003 (total transmission from the South to the Southeast–Midwest increased from 3200 to 4800 MW).9
The South region’s hydrological system is com-pletely different from the Southeast–Midwest region’s hydrological system (which also rules hydropower generation in the Northeast, since the main river that feeds hydropower plants in the Northeast region flows from the Southeast–Midwest to the Northeast).
During the electricity crisis of 2001–2002, rainfall levels in the South region were normal and storage levels were satisfactory. In the period from May 2001 to July 2002, 62.5 TW·h were produced, with 2.6 TW·h of equivalent reservoir storage energy depletion. Total energy flow in the reservoir was 96.8 TW·h in the period, and efficient utilization of the surplus energy
8 Both blackouts occurred in the South, Southeast and Midwest regions. The first occurred on 11 March 1999, affecting 12 States; the second took place on 21 January 2002, affecting 10 States.
24 000 26 000 28 000 30 000 32 000 34 000 36 000
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
MW
1998 1999 2000 2001 2002 2003
FIG. 8.5. Electricity delivery in Brazil's Southeast–
Midwest region, 1998–2003 [8.22].
9 In reality, by 2004 the total maximum transfer from the South to the Southeast–Midwest region was increased from 3200 to 3500 MW, and it is expected to reach 5400 MW only in 2006 [8.22].
— amounting to 34.3 (96.8 – 62.5) TW·h — would have allowed the generation of approximately 32 TW·h. This energy could have been transmitted to the Southeast–Midwest region at a monthly rate of 2.13 TW·h, requiring a transmission capacity of 2.92 MW.
This additional energy would have increased energy availability in the Southeast–Midwest region during 2001 from 99 to 116 TW·h (a 17% increase), reducing the total rationing effort from 25% to only 8%.
Even more important, in June 2000, water avail-ability in the South region started to rise from the minimum equivalent reservoir storage level of 25%.
From June 2000 to April 2001, total energy flow in the reservoir was 58.5 TW·h, while generation was only
39.3 TW·h.10 If the water available had been used efficiently, it would have been possible to generate around 57 TW·h, or a surplus of around 18 (57 – 39.3) TW·h. The transfer of this energy to the Southeast–
Midwest region from June 2000 to April 2001 would have brought the storage capacity of the Southeast–
Midwest region’s reservoir from 37.4 to 55.4 TW·h by April 2001 (see Fig. 8.4), a value that probably would have postponed the decision to apply electricity rationing. Starting with a 55.4 TW·h storage level in Itaipu, 12 600 MW
Paraguay
Garabi, 2000 MW Argentina Venezuela, 200 MW
São Luis
Teresina
Goiânia Brasilia
Belo Horizonte Inter
connection North/South
Interconnection Southwest/Northeast
Paraíba do Sul
Vitoria
Curitiba
Florianópolis Porto Alegre Jacuí
Uruguai Iguçu
Paranapanema
São Paulo Cuiabá
Campo
Grande Grande Paranaíba
Paraná/Tieté
Fortaleza Natal
Recife Maceió Aracaju Salvador
João Pessoa Belem
Parnaiba Tocantias
São Francisco
230 kV 345 kV 500 kV 750 kV 1600 kV CC
FIG. 8.6. Brazil’s interconnected electricity transmission system [8.19].
10 The information included here is from a plot of the South region’s electric subsystem similar to the one shown in Fig. 8.4 [8.24].
the period that rationing was imposed would have allowed the generation of an extra 1.5 TW·h during the full period using the extra water stored in the Southeast–Midwest reservoir. With the extra 2.13 TW·h/month of electricity delivered by the South region (discussed in the previous paragraph), it would have been possible to increase electricity availability in the Southeast–Midwest region by 3.63 TW·h/month during all 12 months of the electricity shortage. In this scenario, electricity availability would have been increased by 29 TW·h during the last 8 months of 2001 and by 14 TW·h during the first 4 months of 2002. Such figures are equivalent to an annual generation of 128 (99 + 29) TW·h in 2001 and 134 (120 + 14) TW·h in 2002 (see Fig. 8.4). Considering that electricity generation in the Southeast–Midwest region in 2000
was 137 TW·h (enough to meet demand), with a 3%
annual growth rate the expected demand would be around 141 TW·h in 2001 and 145 TW·h in 2002.
Potential electricity shortages of 13 and 11 TW·h in each year, respectively, could have been managed more easily or even avoided, since the Southeast–
Midwest reservoir storage level never declined below 21 TW·h in the most critical year of the period (see Fig. 8.4).
It is possible to conclude that an extra trans-mission capacity of 1.8 TW·h/month (2460 MW) in 2000–2001 and 2.13 TW·h/month (2920 MW) in 2001–
2002 would have been enough to mitigate or even eliminate electricity rationing in the Southeast–
Midwest region of Brazil. The conclusion is that a transmission capacity shortage prevented the transfer TABLE 8.1. AVERAGE POWER TRANSFER BETWEEN REGIONS IN THE INTERCONNECTED SYSTEM (MW) [8.22]
1999 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Tr S–SE/MW –2183 –1726 –1479 –1147 –1444 –1738 –726 –713 –1177 –813 –818 –1371
Tr international 0 0 0 –13 –44 –37 –46 –41 –40 –42 –47 –48
Tr N–NE 174 433 656 660 645 652 679 741 787 758 613 0
Tr N–SE 0 21 42 14 18 40 –112 –604 –561 –536 –490 530
2000 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Tr S–SE/MW –2157 –1767 –2198 –2022 –1945 –2304 –1904 –1907 –1150 62 –581 –862 Tr international –43 –42 –40 –60 –214 –597 –971 –1058 –477 –133 –379 –925
Tr N–NE 243 166 122 217 305 339 296 243 305 –13 –50 103
Tr N–SE 666 581 509 510 501 589 356 483 302 276 187 345
2001 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Tr S–SE/MW 325 266 774 883 1569 872 1274 1962 1648 1517 1144 577
Tr international –286 –51 –339 –498 –1038 –1027 –148 –622 –1003 –51 –556 –221
Export N 870 1006 909 1021 1198 1185 613 734 700 823 755 947
Tr N–NE 420 507 493 922 1063 1177 613 734 700 823 755 947
Tr N–SE 450 499 416 99 135 8 0 0 0 0 0 0
Tr S–SE/MW–NE 0 0 0 0 0 0 690 588 590 493 584 342
Import NE 420 507 493 922 1063 1177 1302 1322 1290 1316 1339 1289
2002 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Tr S–SE/MW –1669 –939 –931 –1246 –1217 481 47 –16 80 903 1425 1155
Tr international –512 –46 –46 –63 –53 –96 –53 –45 –41 –41 –41 –40
Export N 937 641 796 785 649 855 858 506 226 –140 –517 –773
Tr N–NE 921 641 796 785 649 845 858 506 226 0 0 0
Tr N–SE 16 0 0 0 0 10 0 0 0 –140 –517 –773
Tr SE–NE 0 667 412 504 198 0 62 383 241 778 640 418
Import NE 921 1308 1208 1289 846 845 919 889 467 778 640 418
Note: TR = transfer; S = South region; SE/MW = Southeast–Midwest region; N = North region; NE = Northeast region.
TABLE 8.2. ELECTRICITY GENERATION AND TRANSMISSION CAPACITIES: SITUATION DURING ELECTRICITY CRISES OF 2001–2002 AND ALTERNATIVE MITIGATION SCENARIO
Region Jan–Apr
2001
May–Dec 2001
Jan–Apr 2002
Apr–Dec 2002
Apr 2003–
Feb 2004 Business as usual scenario
Average electricity generated (TW·h/month)a
SE/MW 10.67 7.09 10.10 9.92
Itaipu 6.88 5.66 6.47 6.37
S 4.73 4.55 3.42 4.71
Total 22.28 17.30 19.99 21.00
Maximum average transmission capacity (MW)b
S–SE/MW 3 200 3 200 3 200 3 200 4 800
Itaipu–SE/MW 10 000 10 000 10 000 10 000 10 000
Total 13 200 13 200 13 200 13 200 14 800
Maximum average transmission capacity used (MW)c
S–SE/MW 883 1 962 0 1 425
Itaipu–SE/MW 9 424 7 753 8 863 8 726
Total 10 307 9 715 8 863 10 151
Higher transmission capacity scenario Average electricity generated (TW·h/month)d
SE/MW 8.87
(10.67 – 1.8)
8.89 (7.09 + 1.8)
11.9 (10.1 + 1.8)
9.92
Itaipu 6.88 5.66 6.47 6.37
S 6.53
(4.73 + 1.8)
6.68 (4.55 + 2.13)
5.55 (3.42 + 2.13)
4.71
Total 22.28 21.23 23.92 21
SE/MW available 10.67
(8.87 + 1.8)
11.02 (8.89 + 2.13)
14.03 (11.9 + 2.13)
9.92
SE/MW demand 11.41 11.76 12.10
Average transmission capacity required (MW)e
S–SE/MW 4 420
(1 960 + 2 460)
4 880 (1 960 + 2 920)
2 920 1 962
Itaipu–SE/MW 9 424 7 753 8 863 8 726
Total 13 844 12 633 11 783 10 688
Average additional transmission capacity required (MW)
S–SE/MW 1 220 1 680 –280 –1 238
Itaipu–SE/MW –576 –2 247 –1 137 –1 274
Total 644 –567 –1 417 –2 512
Note: SE/MW = Southeast–Midwest region; S = South region.
a Values from Ref. [8.19].
b Values from Ref. [8.23].
c Values from Table 8.1.
d Model discussed in Ref. [8.24].
e Values discussed in Section 8.2.4.
of an extra 1.8 TW·h/month (2460 MW) in 2000–2001 and 2.13 TW·h/month (2920 MW) in 2001–2002. In reality, the shortage in transmission capacity was lower, as indicated in Table 8.2 (an average of only 1220 MW in 2000–2001 and 1680 MW in 2001–
2002). In practice, some surplus must be available in the transmission line and some extra 2000 MW of capacity probably would have been enough to mitigate or even avoid the electricity crisis.