Sunlight is needed for photosynthesis because the solar energy is what is converted to chemical energy by the plant's chloroplasts. This energy is necessary for the production of glucose, which provides usable energy for the plant.
The chloroplasts contain the green pigment chlorophyll, which absorbs the sun's light. Two other required ingredients for photosynthesis are carbon dioxide and water. The combination of these three substances fuels the process of photosynthesis, which produces glucose, oxygen and water. Photosynthesis occurs primarily in the leaves of the plants, which contain the highest concentration of chloroplasts. Tiny pores, or stomata, are also located on the plant's leaves and absorb carbon dioxide from the surrounding air.
Protists, bacteria and blue-green algae are other organisms that photosynthesize for nourishment. Additionally, many organisms form symbiotic bonds with photosynthetic organisms, most commonly corals, sea anemones and sponges. Some mollusks even store chloroplasts in their bodies so that they can survive on sunlight alone for several months. In 2010, the Oriental hornet was the first animal discovered to use photosynthesis. The wasp converts sunlight into electrical energy. The efficiency of the conversion from sunlight into chemical energy is approximately 3 to 6 percent, with the unconverted energy being released as heat. Globally, it is estimated that photosynthesis captures about 130 terawatts of energy each year, which is six times larger than human energy consumption.