Low Carbon Grid Study: Analysis of a 50% Emission Reduction in California

Abstract

PrefaceThis study was funded by a variety of industry and foundation sources with the goal of understanding the impacts of a low-carbon grid in California. These organizations put together a Steering Committee to assemble the study team and guide the study process. The Low Carbon Grid Study (LCGS) put out three reports: 1) this one on grid operations, 2) an analysis by GE Energy on reliability impacts of the LCGS scenarios (Miller 2015), and 3) a capital cost analysis by JBS Energy of the LCGS scenarios (Marcus 2015).As experts on renewable energy and energy efficiency deployment in California, the Steering Committee also helped produce the portfolio of renewable energy and energy efficiency technologies that were used as the basis for this study. The study team also assembled a Technical Review Committee, which met throughout the study to review assumptions, methodologies, results, and conclusions. The authors would like to thank the Steering Committee for their support and the Technical Review Committee for lending their time and expertise to improve this study. Although the members of the Steering Committee and Technical Review Committee helped prepare and review this report, this report may not reflect the specific views or interpretations of any member of either committee. Jim Caldwell led the Steering Committee, and the Center for Energy Efficiency and Renewable Technologies was the fiscal sponsor. Executive SummaryThe California 2030 Low Carbon Grid Study (LCGS) analyzes the grid impacts of a variety of scenarios that achieve 50% carbon emission reductions from California's electric power sector. Impacts are characterized based on several key operational and economic metrics, including production costs, emissions, curtailment, and impacts on the operation of gas generation and imports. We used the PLEXOS model to simulate the unit commitment and dispatch of the generating fleet in the western United States for 23 different scenarios, which included a variety of assumptions regarding the generator portfolios, energy efficiency, storage, and grid flexibility. A focus of the study is the impacts of electric system flexibility measures on key operational and economic metrics. The LCGS study comprises three reports: 1) this NREL report on the operational impacts of a low-carbon grid, 2) a report by JBS Energy on the capital costs of the scenarios (Marcus 2015), and 3) a report by GE Energy on the dynamic grid issues caused by high renewable penetrations (Miller 2015).vi This report is available at no cost from the National Renewable Energy Laboratory (NREL) at www.nrel.gov/publications. Table ES-1. Conventional vs Enhanced Flexibility Assumptions Conventional FlexibilityEnhanced Flexibility 70% of out-of-state (CA-entitled 2 ) renewable, nuclear, and hydro generation must be imported Only physical limitations on imports and exports 25% of generation in California balancing authorities must come from local fossil-fueled and hydro sources No minimum local generation requirements 1.5 GW battery storage to meet CA ...

Capturing the Impact of Storage and Other Flexible Technologies on Electric System Planning

“…To implement this curtailment method, we generated a regression model for the effective minimum generation of each NERC sub-region as a function of variable generation capacities. This regression is calculated using production cost model results from two WECC-wide studies (Lew et al 2013;Brinkman et al 2015), which are used as training data for the regression. This method of calculating the effective min-gen does not explicitly account for transmission between regions, nor does it account for upgrades in the transmission network that the model might build.…”

“…Flexibility assessment has become an integral part of grid integration studies for renewables (GE Energy 2010;Lew et al 2013;EnerNex Corporation 2011;Bloom et al forthcoming;Venkataraman et al 2010;E3 2014;GE Energy 2014;Brinkman et al 2015). These studies use high-resolution models of grid operations (i.e., production cost models) to assess how the introduction of greater shares of variable renewable generation might affect production costs, emissions, and the mix of generated electricity.…”

Curtailment of Renewable Energy in California and Beyond

“…In Phase 1 of the study, they found a worstcase scenario with curtailment as high as 11.9 percent. 47 But deploying a variety of mitigation options, most notably regional trade across the Western U.S., curtailment was dramatically reduced.…”

“…3) To what extent will renewables be curtailed with a higher (40)(41)(42)(43)(44)(45)(46)(47)(48)(49)(50) There are many different definitions of curtailment and there is no standardized way to measure it. 1 For the purposes of this article, we define curtailment as a reduction in the output of a wind or solar generator from what it could otherwise produce given available resources like wind or sunlight.…”

CO2 emissions associated with electric vehicle charging: The impact of electricity generation mix, charging infrastructure availability and vehicle type

“…These results were aggregated to produce annual average hourly profiles (shown in Figure 1). The main analysis is based on a "standard scenario," which assumes moderate renewable energy build-out and accounts for planned closures of coal facilities and anticipated growth in natural gas generation (Brinkman 2015;Bloom et al 2016). In addition, a sensitivity analysis (presented in a later section) was conducted for cases with high and low percentages of renewable energy.…”