**5.1 Logistical challenges**

Collecting oilseed waste from diverse sources presents a logistical challenge. Establishing an efficient collection system requires collaboration with local bodies and cooperatives. Optimizing biomass logistics, including transportation from collection points to processing facilities, is crucial to reduce costs and energy inputs.

## **5.2 Oilseed variability**

OSR from different plant species exhibits significant variability in oil content due to various genetic, environmental, and agricultural factors. Understanding and managing this variability are crucial for ensuring a consistent and reliable feedstock supply. Plant breeding and selection, monitoring of crop growth, proper soil management, and suitable irrigation strategies can help mitigate the impact of environmental factors on oil yield [11].

## **5.3 Non-edible seed residue**

The development of non-edible crops as potential feedstock for biodiesel presents unique challenges toward achieving self-reliance in energy security. These challenges include the forest origin of non-edible crops, making harvesting, collection, and transportation difficult. Additionally, lower fuel economy, seasonal availability, improper marketing channels, and high FFAs and moisture content in non-edible oils require pre-treatment before the transesterification process. The lack of post-harvest technologies further affects the oil quality of non-edible crops [41].

#### **5.4 Seasonal nature and annual variability**

The seasonal nature of oilseed cultivation results in fluctuations in feedstock supply, which can affect continuous production processes. Addressing these fluctuations requires effective planning and coordination of agricultural activities. Despite the challenges, non-edible crops offer opportunities for cultivating harsh and unused lands in developing countries, such as seashores, riverbanks, deserts, and wastelands. These crops could maximize land utilization for crop production. Implementation of advanced technology, particularly waterless extraction technology like supercritical fluids, offers potential solutions to avoid FFAs and moisture content in non-edible oil [42].

#### **5.5 Efficient storage and self-decomposition**

Proper storage of oilseed waste is essential to maintain its quality and energy potential. Prolonged on-site storage, however, can lead to self-decomposition and the release of harmful gases, posing environmental and safety risks. Developing appropriate storage techniques is critical to preserve the feedstock's quality [43].
