Influence of ENSO on renewable U.S. energy supply

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Tuesday, 19 January 2010: 2:30 PM
B202 (GWCC)
Klaus Wolter, CIRES/Univ. of Colorado, Boulder, CO

The fraction of renewable energy generation as part of the total energy supply of U.S. is still quite small. Due to current predictive capabilities, and inherent degree of variability due to changing weather patterns, most public utilities have installed back-up energy supply power plants to ‘jump into the breach' whenever renewable energy supplies are reduced. As we move forward to a future with a higher percentage of U.S. power generation from renewable energy sources, it will become less feasible to keep installing back-up power plants to cover for unpredicted losses in the renewable domain.

With regard to wind energy, there is a range of wind speeds that can be utilized to run wind turbines, but both extremely low and high wind speeds can disable their usage. A lesser known cause for wind turbine stoppage are sub-zero temperatures, something that occurs often enough in the northern high plains to become a factor despite favorable wind speeds.

With regard to solar energy, the main threat to solar energy production is from heavy cloudiness, but also from very high temperatures (that reduce the output from Photovoltaic power plants), and from snow and dust that affects all forms of solar power generation.

The seasonal forecasting community has long used the known impacts of ENSO phases on U.S. temperature and precipitation anomalies to shape their long-range forecasts. As far as I know, there is no similar (public-sector) effort going on to predict seasonal anomalies of wind- and solar power based on the phase of ENSO. This paper attempts to start to fill that gap by mining reanalysis data for both solar and wind information in the last three decades with respect to ENSO. Of particularly high interest is the co-variability of regional renewable energy supplies during the main El Niño and La Niña events of this period. How large are the fluctuations in this historical record, what are the worst-case scenarios, and how reliable are these ENSO-related features? These are some of the questions this presentation is aimed to address.