Highlighting and overcoming data barriers: creating open data for retrospective analysis of US electric power systems by consolidating publicly available sources

Studies of power system operation commonly draw from two key databases produced by the US Environmental Protection Agency: the Acid Rain Program's Continuous Emission Monitoring System (CEMS) data, and the Emissions and Generation Resource Integrated Database (eGRID). Separate reporting requirements and heterogeneity in data aggregation between these two databases creates a barrier to systematic spatial and temporal retrospective power system analysis. This work describes the inherent challenges to this undertaking and documents a method for reconciling the two seemingly disparate data sources. While fundamental differences in data reporting and aggregation prevent us from achieving full coverage, this work represents an important initial step to aligning these two repositories of US power system data. We demonstrate the value of this linkage by computing relative unit-level, hourly utilization metrics for most thermal power plants in the US. Analysis of these metrics across time illustrates thermal generator cycling trends in California between 2011 and 2017. These unit-level results indicate that combined cycle units within California increased their part-load generation by 15% and resultant CO2 emissions by 17% and decreased their start/stop frequency over time by 8.5% and resultant emissions by 47%. Open cycle gas turbines overall increased their generation- number of start/stop cycles by 97% and resultant emissions by 85%, part-load generation by 120% and resultant emissions by 100%, and full load generation by 40% and resultant emissions 18%. We also observe a temporal shift in thermal generation from morning hours to evening in California.