Electricity Customers as Batteries? Exploring the Demand-Side Management Strategies to Balance Solar Energy

Abstract:

The electricity sector is decarbonizing through the expansion of renewable energy resources, primarily solar and wind energy. In California, solar energy has grown exponentially in the last decade, and it will continue to grow as the state seeks to achieve 100% clean energy by 2045. However, in the absence of storage, solar energy can only be used during daytime when it is available. Fossil fuel-based generators, namely natural gas, typically ramp up significantly to meet demand as solar generators go offline in the early evening, when demand tends to be highest across the state. This creates large differences in the emissions embedded in a unit of electricity consumed in midday, when solar generators are dominant, versus in the early evening, when natural gas generators are dominant. Moreover, solar generation in California can be so high that it is actually curtailed when the expected electricity generation (including renewables) exceeds real-time demand, effectively wasting an emissions-free source of generation.

In this study, we evaluate the efficacy of demand-side management interventions in California that shift electricity demand from peak demand evening hours to times of high renewable energy generation in terms of: 1) mitigating greenhouse gases by avoiding electricity consumption when generation is dirtiest, and 2) reducing solar overgeneration. Our framework models the relationship between the electricity supply mix (from natural gas, hydropower, and renewables) and greenhouse gas emissions to quantify the sensitivity of the time-varying emissions intensity of the grid to changes in electricity demand and renewable energy availability. Thus, it examines the role of marginal generators in affecting grid-derived emissions in order to evaluate the potential of demand shifting strategies for avoiding carbon dioxide emissions, rather than the grid-averaged fleet. California is selected as a case study because its grid already has high penetrations of solar energy and its solar overgeneration issue has become worse over time. This study offers a novel framework and analysis to evaluate electric load shifting strategies that can potentially support deeper decarbonization pathways by enabling higher penetrations of renewable energy without costly storage technologies.