The role of climate forecasts in western U.S. power planning


Voisin, N., Hamlet, A.F., Graham, L.P., Pierce, D.W., Barnett, T.P., Lettenmaier, D.P. 2006. The role of climate forecasts in western U.S. power planning. Journal of Applied Meteorology 45(5):653-673.


Climate and climate variability affect power supply and consumption in ways that are increasingly predictable. Seasonal and interannual climate variability along the U.S. west coast varies in such a way that California (CA) and the Pacific Northwest (PNW) are often out of phase in terms of power supply and demand. For instance, warm and dry winters in the PNW (and hence reduced hydropower production) often occur at the same time as cool and wet conditions in southern CA. These conditions can now be forecast with some skill as much as a year in advance.

We describe models that make use of climate forecasts to simulate the operations of the Columbia River, and the Sacramento-San Joaquin reservoir systems for the period 1917-2002. We use these simulations to examine the potential for alternative operation of the existing power intertie between the PNW and CA (capacity ~7900 MW) that might exploit out of phase climate behavior between the PNW and CA.

Our results show that hydropower production and electricity demands are out of phase seasonally, but tend to covary on an annual basis, in response to ENSO climate signals. Potential hydropower transfers are shown to be correlated to ENSO and PDO and the probability distributions of these transfers are therefore predictable with long lead times. Such electricity transfers are estimated to have potential

average annual benefits to CA and the PNW of $159 M and $95 M respectively. By exploiting the long-range predictability of spring surplus hydropower production in the PNW, increased electricity transfers in late summer could be facilitated in some years where surplus electricity is likely with increased economic benefits to the PNW and reduced risks of capacity related failures in CA.