For this project the most appropriate solution to save the burst of energy is Super-capacitor. Thus the need of hour is to enlighten the advantages of super capacitor over other energy storing devices, do some research on it and document short (One page max.) feasibility report of application in gravity harvester.
supercapacitors are basically the energy storing devices which can store the high amount of energy as compared to a normal capacitor. it gives more power than the batteries but can store less energy that the battery. Super-capacitor differs than normal capacitor when it comes to construction. there are two electrolytic layers and a semi-permeable membrane separating them. in the normal capacitor, there is dielectric material between the two electrodes. semipermeable membrane only allows ions to flow. ions can flow in the electrolyte freely, when the battery is connected to this supercapacitor electrodes are charged and hence pulling all the opposite charged ions from the electrolyte towards themselves and hence forming two different capacitors forming on two electrodes in series.
for working check out this video