An emission inventory system for biogenic sources of hydrocarbons has been developed. It is based on modifications of the classic formula: Emissions = Sigma Biomass Area Emission Factor. It accommodates multiple sources with emission factors dependent on season, temperature and solar intensity. It provides emissions on a latitude/longitude based grid system aggregated by plant specie, hydrocarbon compound, study area (county, state, etc.), or time interval. The emission calculations from the inventory have better spatial, source, temporal and hydrocarbon compound resolution than prior work has provided.