Electricity cannot be cost-effectively stored even for short periods of time. Consequently, wholesale electricity prices vary widely across hours of the day with peak prices frequently exceeding off-peak prices by a factor of ten or more. Most analyses of energy-efficiency policies ignore this variation, focusing on total energy savings without regard to when those savings occur. In this paper we demonstrate the importance of this distinction using novel evidence from a rebate program for air conditioners in Southern California. We estimate electricity savings using hourly smart-meter data and show that savings tend to occur during hours when the value of electricity is high. This significantly increases the overall value of the program, especially once we account for the large capacity payments received by generators to guarantee their availability in high-demand hours. We then compare this estimated savings profile with engineering-based estimates for this program as well as a variety of alternative energy-efficiency investments. The results illustrate a surprisingly large amount of variation in economic value across investments.

中文翻译：

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能效投资是否在正确的时间交付？

即使是短时间，也无法经济高效地储存电力。因此，批发电价在一天中的几个小时内变化很大，高峰价格经常超过非高峰价格十倍或更多。大多数能效政策的分析都忽略了这种变化，只关注总节能量而不考虑节能量何时发生。在本文中，我们使用来自南加州空调回扣计划的新证据证明了这种区别的重要性。我们使用每小时智能电表数据估算节电，并表明节电往往发生在电力价值高的时段。这显着增加了程序的整体价值，尤其是当我们考虑到发电机收到的大容量付款以保证它们在高需求时段的可用性时。然后，我们将这个估计的节省情况与该计划的基于工程的估计以及各种替代能源效率投资进行比较。结果表明，不同投资的经济价值存在惊人的巨大差异。