Alan F. Hamlet, Nathalie Voisin,
Dennis P. Lettenmaier, David W. Pierce
Center for Science in the Earth System Climate Impacts Group
and Department of Civil and Environmental EngineeringUniversity of Washington
Scripps Institute of OceanographyCalifornia Energy Commission
January, 2005
Effects of Climate Variability on Hydropower Production and
Energy Demand in CA and the PNW
Background
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Effects of the PDO and ENSO on Columbia River Summer Streamflows
Cool CoolWarm Warm
PDO
Red=warm ENSO Green=ENSO neutral Blue=cool ENSO
Value of Long-Range Streamflow Forecasts for PNW Hydro Marketing
~ $150 million/yr
This value is created in part by marketing additional energy in late summer (when energy is more valuable) in expected wet years.
Hamlet, A.F., Huppert, D., Lettenmaier, D.P., 2002, Economic Value of Long-Lead Streamflow Forecasts for Columbia River Hydropower, ASCE J. of Water Res. Planning and Mgmt, 128 (2), pp 91-101
http://www.abb.com/global/abbzh/abbzh251.nsf!OpenDatabase&db=/global/gad/gad02181.nsf&v=17EA&e=us&m=100A&c=C1256D71001E0037C1256B8000371E41
~8000 MW IntertieCapacity
In normal or above normal water years in the PNW, net transfers are typically from PNW to CA
In below normal water years in the PNW, transfers from CA to PNW can occur in winter and transfers from PNW to CA in spring and summer may be
reduced or suspended.
Research Questions:
How do hydropower resources in the PNW and CA vary with climate and how predictable are these variations?
How does electrical demand vary with climate in the PNW and CA and how predictable are these variations?
How do supply and demand co-vary in time? How predictable are energy surpluses and deficits in each region?
How can we best use this information to maximize the benefits of the PNW - CA electrical intertie?
Tools and Methods
Snow Model
Schematic of VIC Hydrologic Model and Energy Balance Snow Model
PNW
CACRB
GB
Met Data1915-2003
VIC
Overview of Simulation and Analysis
CVMod
ColSim PNW Hydro
SacramentoSan Joaquin Hydro
StatisticalDemand Models
PNW Demand
CA Demand
Population Weighted
TemperatureTime Series
Urban PopulationData
Observed DemandData
Results
Evaluation of VIC Streamflow Simulations
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191719221927193219371942194719521957196219671972197719821987199219972002
PNW*
CA*
Covariation of Normalized PNW and CA Hydropower Production
California hydropower is less than 10% of total CA demand, but may play a significant role in energy trading on short time scales.
R2 =0.541
Evaluation of Daily Time Step Energy Demand Model
Demand vs Tmax
Model Validation
Predictability of Seasonal Demand in the PNW and CA
•Winter demand in the PNW is predictable with long lead times via ENSO forecasts:
Warm ENSO = lower winter electrical demandCool ENSO = higher winter electrical load
•Load is in phase with water availability.
•Summer demand in CA has been recently demonstrated to be predictable with several months lead time using the NPO (PDO) index in spring (Alfaro et al. 2005). Even longer lead times may be possible.
B.Normal NPO (MAM) = lower CDD in S. CA. (JJA)A.Normal NPO (MAM) = higher CDD in S. CA. (JJA)
•Load is out of phase with PNW water availability.
May-June-July Hydropower available for Transfer
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PDO
ENSO
Available Energy
Above normal surplus hydro from the PNW is more likely in cool PDO and cool ENSO years, less likely in warm PDO and warm ENSO years.
Year to year variations are compressed by covariation of supply and demand (i.e. low water typically is simultaneous with low demand).
Probability of Exceedance for Spring Surplus Energy Resources in the PNW
A Forecast Timeline
Jun Aug Jun
On ~June 1 we have:
•CurrentReservoirContents (PNW and CA)
•Current SummerStreamflow Forecast (PNW and CA)
•ENSO forecast•PDO forecast
CA Demand
Surplus PNWEnergy forComing Spring
PNW Winter Demand
Jan
Forecasts: