hydrology days 2004 applied stochastic hydrology lessons learned from the brazilian electric energy...
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Hydrology Days 2004
Applied Stochastic Hydrology Lessons Learned from the Brazilian
Electric Energy Crisis of 2001
Jerson KelmanPresident of ANA
(Brazilian Water Resources Agency)
Area: 8,574,761 km2 Average Temperature: over 20ºCFederative Republic: - 26 States + 01 Federal District - 5,561 Municipalities13 River basins
BRAZIL
Hydroelectric power accounts for more than 90% of the total
electric energy produced in Brazil
BRAZILIAN ELECTRIC SYSTEM
MAIN CONSTRUCTIVE SYSTEMS USED
Compacted rock fill with concrete faceCompacted rock fill with impervious coreEarth fillConventional concreteRolled compacted concrete (RCC)
SEGREDO HYDRO PLANTA compacted rock fill structure with an
upstream concrete face
SALTO SANTIAGO HYDRO PLANTRock fill dam with impervious clay core
FURNAS HYDRO PLANTA construction of zoned earth and rock fill
dam
SOBRADINHO HYDRO PLANTThe typical section is a zoned embankment type,
comprising a clay central impervious core
SALTO CAXIAS HYDRO PLANTRolled Compacted Concrete (RCC)
ITAIPU HYDRO PLANTA buttress concrete structure
Vast territorial extension and hydrological variability
Country Wide Integrated Electric System
BRAZILIAN ELECTRIC SYSTEM
INTEGRATED ELECTRIC
SYSTEM Installed Capacity = 72,299 MW
96 Hydropower plants > 30 MW
57 Regulating reservoirs
Country is interconnected by 44,000
miles of high-voltage lines
INTEGRATED ELECTRIC
SYSTEM Up to 1996, new hydroelectric power
plants were built almost exclusively
by the Federal and State
Governments
Expansion planning was based on
reliability criteria: probability of any
energy shortage along a year would
be 5%
INTEGRATED ELECTRIC
SYSTEM All power plants, hydro and thermal,
were centrally dispatched, taking
advantage of the hydrological
complementarities among river
basins
Stochastic Dynamic Stochastic
Programming was used to decide
how to split energy production
between hydro and thermal sources
When the use a mathematical model to dispatch power plants is necessary?
If the system is thermal, it isn’t. Example: Suppose demand = 20 and three generators
The dispatch would be G1=10; G2=5; G3 = 5
Marginal cost = spot price = 15
Generator Cost
($/energy unit)
Capacity
G1 8 10
G2 12 5
G3 15 20
When the use a mathematical model to dispatch power plants is necessary?
If the system is hydro, it is.
wet
dry
OK
Deficit dry
wet
Future inflows
Use stored water
Decision
Do not use stored water
OK
Consequências operativas
Spill
When the use a mathematical model to dispatch power plants is necessary?
If the system is hydro, it is. Z = Max E [ immediate cost + future cost ]
Marginal cost = spot price = Z/ demand
wet
dry
OK
Deficit dry
wet
Future inflows
Use stored water
Decision
Do not use stored water
OK
Consequências operativas
spilling
THE POWER SECTOR REFORM
The reform process started in 1996
Rationale:
– Public sector has no $ to invest
– To promote economical efficiency
Guidelines:
– Private investment and competition in energy generation and retailing
– Transmission and distribution to remain regulated, with provisions for open access
Reforms based on the same principles had worked in countries based on thermal production.
Would it work in a country like Brazil, based on hydro?
THE POWER SECTOR REFORM
Simulação do comportamento do reservatório de FURNAS(Vazão firme = 670 m³/s)
0
5000
10000
15000
20000
25000
Mês/ano
Volu
me
(hm
³)
Armazenamento final (hm3) Volume Morto (hm3)
Nov/56 = 5733 hm³
Volume morto = 5733 hm³
Fonte dos Dados: ONS
Reservoirs are full most of the time
Storage variability
SOUTH-SE SystemEnergy Wholesale Market Prices (US$ / MWh)
Sampling probability distribution of spot price (R$/MWh)
0.0
100.0
200.0
300.0
400.0
500.0
600.0
1 4 7 10 13 16 19 22 25 28 31 34 37 40 43 46 49 52 55 58 61 64
spot mean
EVOLUTION OF THE STORED ENERGY IN THE EQUIVALENT RESERVOIR OF
THE NORTHEAST REGION
ENERGIA ARMAZENADA (% DO VALOR MÁXIMO)
0
10
20
30
40
50
60
70
80
90
100
jan
/97
jul/9
7
jan
/98
jul/9
8
jan
/99
jul/9
9
jan
/00
jul/0
0
jan
/01
jul/0
1
jan
/02
THE ENERGY CRISIS OF 2001
There was a market failure
As a consequence…
•20% of the energy demand had to be curtailed in 2001
•Population reacted better than expected:
consumption reduction remains until now
THE ENERGY CRISIS OF 2001
How to prevent market failures?
• Brazilian Government restored centralized expansion planning for new plants and transmission lines
• Reliability criteria is being modified. For example:
P (Curtailment < 0.05 Demand) < 0.1
P (Curtailment > 0.20 Demand) < 0.001
P (Curtailment | occurrence of worst drought) = 0
THE ENERGY CRISIS OF 2001
How to prevent market failures?
• Owner of a new hydroelectric plant will get, before construction, a long term contract with a pool of distribution companies (equivalent to an annual “rent”)
• All power plants will operate according to rules set by central dispatch, based on a multiple reservoirs Stochastic Dual Dynamic Programming Model (SDDP)
Should hydro be abandoned?
Cost of new energy (US$/MWh)
Hydro 30
Thermal 40
Alternative 50
Amazon Region
CHEBelo Monte
Rio
Xin
gu
Localization
Total Capacity (MW)
Energy (MW méd)
Xingu River(PA)
11.182
4.796
Reservoir Area (103 acres) 110
Belo Monte
Conclusions
The energy crisis of 2001 has shown that the electric energy business based on hydro requires more than regulation it requires Government planning
When the crisis occurs, planning criteria based on the probability concepts are difficult to understand. The concept of trade off between reliability and cost was ill perceived by the population the old concept of firm energy is better accepted
Conclusions
Brazil needs to ensure a sustainable growth of energy supply
Hydroelectricity cannot be spared
The strategy is to select, from the numerous sites technically and economically feasible for hydroelectric power plants, a subset that would cause minimum environmental and social impacts
However, we are not seeking for a subset that would cause no impact