Optimal Investment in Wind and Solar Power in California, 2010-2025
This page updated January 22, 2009
Chair’s Air Pollution Seminar
Tuesday, February 17, 2009
Optimal Investment in
Wind and Solar Power
Matthias Fripp, Ph.D.
and solar power are increasingly attractive sources of electricity as
their costs fall and our desire to avoid greenhouse gas emissions
rises. However, these technologies generate power only when the wind
and sun are available, so it is unclear how large a role they should
play in California's power system in the future.
To address this question, a new model has been developed that seeks to identify the least expensive set of investments in wind, solar and conventional generators and transmission lines, to provide a reliable power supply for California in 2010–25, while accounting for the value of avoiding carbon dioxide emissions. The Switch model (a loose acronym for solar, wind, hydro, and conventional generators and transmission) optimizes future investments in generators and transmission capacity, based on a detailed representation of the hour-by-hour behavior of each of these components. Weather conditions during each hour of the study are based on historical data, so that the optimization incorporates any correlation between wind, sunshine and loads throughout the state.
This model provides a new ability to see how the optimal design of the power system changes depending on the costs that are forecast for generators, fuel and greenhouse gas emissions. This makes it possible to assess how far electricity-sector emissions can be reduced while remaining within a pre-set financial budget, or conversely, to identify the minimum cost of achieving any level of emission reductions.
The Switch model has been used to develop several outputs that are potentially useful to California policymakers. For example, a “supply curve” shows the magnitude of emission reductions that could be achieved in California's electric power system if carbon dioxide emissions are valued at various levels between $0 and $200/ton. In principle, this could be combined with similar supply curves from other sectors in order to allocate emission reduction targets efficiently among all sectors of the economy.
Economic factors have been investigated that are likely to limit the use of renewable power, as such, cost of power will rise gradually if wind and solar power are used on a larger scale: in part because these resources will need increasing amounts of backup power from other sources, but more importantly, because they will eventually begin to generate unneeded power during some hours. However, there appears to be no sharp limit to the cost-effective use of these technologies, even when providing half or more of the system’s power.
the Next Era Research Fellow in Renewable Energy at the University of
Oxford, United Kingdom. Dr. Fripp's research focuses on using
optimization models to assess the role that renewable energy should
play in large-scale power systems in the next two decades. Dr. Fripp's
dissertation research addressed this question in the State of
California, and he is currently working to replicate this analysis in
the United Kingdom, and to extend it to consider the potential for
dramatic emission reductions if renewable resources are complemented by
strong demand-side responses – e.g., well-timed charging of plug-in