To combat the issue of plastics contamination of the medium, the current technologies are aiming towards development of green materials that are substituting the harmful elements from the disposed devices. This article opens a fresh perspective on designing novel polymer composites by loading hydroxypropyl methylcellulose (HPMC) with bio-derived filler or a mixture of bio-filler and barium titanate (BT) to make alternative eco-compatible materials for energy storage. New insights are extracted from a detailed analysis that correlates the solution behavior to solid state analysis. Rheological data evidence that for attaining uniform dielectric layers spinning times beyond 100 s and spinning speeds below 80 rpm are required. Interfacial compatibility with metal electrodes is checked via experiments of sample wetting on silver or gold layer, showing that adhesion work is increased of 6.24 times for gold support and 5.63 times for silver support, being adequate for capacitor applications. The sample morphology was recorded by scanning electron microscopy, indicating good dispersion of the filler or filler mixture in the bulk cellulose derivative matrix. Refractometry experiments revealed an enhancement of molecular polarizability upon loading, which led to increase of refractive index from 1.52 for neat HPMC to 1.56 for HPMC/oat 40 and 1.57 for HPMC/oat + BT 40, at 489 nm. This is reflected in the increase of the dielectric constant at 1 KHz, namely: 2.19 (HPMC) to 2.79 (HPMC/oat 40) and 3.36 (HPMC/oat + BT 40). The dielectric breakdown is slightly lowered upon loading from 43.8 ∙106 V/m (matrix) to 42.3∙106 V/m (HPMC/oat 40) and 42.0∙106 V/m (HPMC/oat + BT 40). The resulted electric energy density values reach at highest loading the values of 2.198∙104 J/m3 for the sample with oat and 2.635∙104 J/m3 for the sample with oat and BT. This work is a fresh initiative of making eco-compatible dielectrics for future storage systems.