This API provides data on sulfur content in fossil fuels. Data organized by fuel type, i.e., coal, bituminous coal, subbituminous coal, lignite coal, petroleum liquids, and petroleum coke. Also by sector, i.e., electric power, electric utility, independent power producers, commercial, and industrial. Annual, quarterly, and monthly data available. Based on Form EIA-423 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