# Machine Learning Technologies in the Supply Chain Management Research of Biodiesel: A Review
## 2 Biodiesel Supply Chain Management
### Supply Chain Management  
Similar to other manufacturing industries, the goal of supply chain management of biofuel is to identify a way of generating efficient flows of materials among vendors, facility warehouses, and customers [24]. In general, a supply chain consists of retailers, distributors, transporters, storage facilities, and suppliers [25]. It is the integration of all stages of the production lifecycle, starting from design and material sourcing, through manufacturing, to delivery to customers [26]. Supply chain management has been widely used to coordinate all the stages that in other contexts might appear independent. It acknowledges that any factor impacting a specific point in the supply chain influences its overall performance [27]. Although there are multiple issues involved in improving the performance of a biodiesel supply chain, the significant issues include transportation cost minimization, productivity maximization, and production cost minimization [28]. Therefore, in a grain-based biodiesel supply chain, activities involving feedstock harvesting, feedstock conversion to biodiesel, and biodiesel distribution should be considered for cost-effective supply chain management [29]. More specifically, the supply chain for grain-based biodiesel consists of seven stages of biomass production farm, biomass storage sites, pre-processing facilities, biorefineries, distribution centers, service stations, and customers. The first stage is to build cultivation facilities. This is because biodiesel is an energy made up of biomass, such as soybean and sunflower. The yield of biomass is heavily influenced by factors such as the duration of the harvest season, the timing of harvesting operations, and weather condition [30]. Therefore, the land availability and suitability for producing raw materials need to be determined [27]. After harvesting crops from cultivation facilities, they are moved to biomass storage sites. The storage of biomass is challenging; due to its high moisture content, it is necessary to use specialized storage systems to minimize any loss in the quantity and quality of biomass. Therefore, growers should focus not only on maximizing biomass yield but also on equipment availability, weather conditions, and the maturity of the plants [31]. The biomass is then moved to pre-processing facilities. Biomass should be pre-processed to reduce its moisture content and particle size. Smaller particles can improve the efficiency and speed of conversion [32]. After it is pre-processed, it is moved to biorefineries. In the above process of transporting feedstock, trailer trucks are mainly used [33]. The biomass can be converted into biodiesel in biofernies [34]. In this process, transesterification is normally used to produce biodiesel [1]. Vegetable oil is transesterified with alcohol to produce biodiesel and glycerol [35]. The produced biodiesel is then moved to distribution centers and service stations that can supply customers [30]. In contrast to the trailer trucks used to transport feedstock, tanker trucks are used when transporting liquid such as biodiesel [33]. Biodiesel can be marketed either as pure biodiesel (B100) or transported to blending facilities to create a 10% blend (B10), which is then stored and distributed [35]. In addition, there are three decisions that should be considered to make an efficient biofuel supply chain. The decisions involve strategic, tactical, and operational decisions. The strategic decisions are decisions that are challenging to change in a short period, and these can be used to design a supply chain, including the location, capacity, and technology used in biorefineries. The tactical decisions are medium-term activities, ranging from a few months to one year, such as inventory planning. Lastly, the operational decisions are short-term activities that involve creating schedules for biofuel production units [36]. Therefore, to design an efficient biofuel supply chain, decisions must be optimized to reduce total costs or maximize profits for the entire system [24].