On the Marginal Value of Electricity Storage

TL;DR

This paper analyzes the economic value of energy storage for wind power producers in electricity markets, showing that small storage capacities provide the greatest marginal benefit and deriving formulas relating storage value to wind variability.

Contribution

It provides a convex optimization framework for assessing the value of energy storage and characterizes the marginal benefits of small storage capacities for wind power producers.

Findings

Maximum expected profit is concave and non-decreasing in storage capacity.

Small storage capacities yield the highest marginal value.

Derived formulas relate storage value to wind power variability.

Abstract

We investigate the problem of characterizing the economic value of energy storage capacity to a wind power producer (WPP) that sells its energy in a conventional two-settlement electricity market. The WPP can offer a forward contract to supply power in the day-ahead market, subject to financial penalties for imbalances between the contracted power and the power that is delivered in real-time. We consider the setting in which the WPP has access to a co-located energy storage system, and can thus reshape its wind power production subject to its storage capacity constraints. Modeling wind power as a random process, we show that the problem of determining optimal forward contract offerings--given recourse with storage--is convex. We further establish that the maximum expected profit is concave and non-decreasing in the energy storage capacity, which reveals that the greatest marginal benefit from energy storage is derived from initial investment in small storage capacity. We provide a characterization of the marginal value of small energy storage capacity to the WPP. The formulae we derive shed light on the relationship between the value of storage and certain statistical measures of variability in the underlying wind power process.