Data on the quality of coal. Determined by the percentage of sulfur in the coal. Data organized by electric power sector, i.e., electric utility, independent power producers, commercial and institutional, and coke plants. Quarterly and annual data available. Based on Form EIA-3 and Form EIA-923 data.Users of the EIA API are required to obtain an API Key via this registration form: http://www.eia.gov/beta/api/register.cfm