There are many components of a biofuel supply chain and many things to consider when investigating the efficiency of the entire system. Researchers are looking at each step necessary to get biomass from the forest to the refinery. They are studying how the location of biomass, seasonality of harvest, type of storage, and combination of equipment used in harvest and transport might affect efficiency. Some research looks specifically at the greenhouse gases emitted during the process. In addition, several researchers are creating models that represent the entire supply chains for producing bioenergy. This will provide a way to examine how to increase energy and cost savings while satisfying biomass demands.