During the light reactions of photosynthesis, plants convert light energy into
energy the plant can use. where is this energy stored?

Once plants convert sunlight into energy, energy molecules help to turn the fuel into sugars in the plant's energy factories called chloroplasts found in the leaves. Through the process of photosynthesis and respiration, plants produce glucose or sugar and oxygen.

Atp is is our little "pocket" of energy. of course, if you have too little, then it means you have too little energy, and you'll pass out. the way to not have enough, is to have no energy sources (glucose, fats, proteins). you can't have too many atp molecules. cycles like the krebs cycle produce it, but if you have too much of any substrate (or too little for that matter), the cycle stops and atp is no longer made (it stops until substrate levels are such that the process can go on). in any case, this is unlikely since atp is constantly hydrolyzed and remade, even while you're asleep. you won't have too much. if you have zero, you are dead or dying.