▁energy ▁obtained ▁from ▁the ▁potential ▁energy ▁of ▁descent ▁may ▁be ▁used ▁to ▁start ▁asc ending ▁the ▁next ▁grade ▁such ▁as ▁what ▁happens ▁when ▁a ▁road ▁is ▁und ulating ▁and ▁has ▁frequent ▁di ps . ▁The ▁commercial ization ▁of ▁stored ▁energy ▁( in ▁the ▁form ▁of ▁rail ▁cars ▁raised ▁to ▁higher ▁elev ations ) ▁that ▁is ▁then ▁converted ▁to ▁elect rical ▁energy ▁when ▁needed ▁by ▁an ▁elect rical ▁grid , ▁is ▁being ▁undert aken ▁in ▁the ▁United ▁States ▁in ▁a ▁system ▁called ▁Advanced ▁Rail ▁Energy ▁Storage ▁( A RES ). ▁ ▁Further ▁information : ▁Gra v it ational ▁potential ▁energy ▁storage ▁ ▁Chem ical ▁potential ▁energy ▁ ▁Chem ical ▁potential ▁energy ▁is ▁a ▁form ▁of ▁potential ▁energy ▁related ▁to ▁the ▁struct ural ▁arrangement ▁of ▁atoms ▁or ▁mole cules . ▁This ▁arrangement ▁may ▁be ▁the ▁result ▁of ▁chemical ▁b onds ▁within ▁a ▁mole c ule ▁or ▁otherwise . ▁Chem ical ▁energy ▁of ▁a ▁chemical ▁subst ance ▁can ▁be ▁transformed ▁to ▁other ▁forms ▁of ▁energy ▁by ▁a ▁chemical ▁reaction . ▁As ▁an ▁example , ▁when ▁a ▁fuel ▁is ▁burn ed ▁the ▁chemical ▁energy ▁is ▁converted ▁to ▁heat , ▁same ▁is ▁the ▁case ▁with ▁dig estion ▁of ▁food ▁met abol ized ▁in ▁a ▁bi ological ▁organ ism . ▁Green ▁plants ▁transform ▁solar ▁energy ▁to ▁chemical ▁energy ▁through ▁the ▁process ▁known ▁as ▁photos yn thesis , ▁and ▁elect rical ▁energy ▁can ▁be ▁converted ▁to ▁chemical ▁energy ▁through ▁electro chem ical ▁re actions . ▁ ▁The ▁similar ▁term ▁chemical ▁potential ▁is ▁used ▁to ▁indicate ▁the ▁potential ▁of ▁a ▁subst