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

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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: