Final answer:
The energy to convert CO2 into sugars in chloroplasts during photosynthesis is provided by ATP, which is synthesized during the light-dependent reactions using solar energy.
Step-by-step explanation:
The fuel that provides the energy to convert carbon dioxide (CO2) into sugars in chloroplasts is derived from the process of photosynthesis. This process harnesses solar energy to synthesize glucose from CO2 and water through a series of reactions. The light-dependent reactions of photosynthesis capture solar energy and convert it into chemical energy stored in ATP (adenosine triphosphate) and NADPH. These molecules then provide the energy that is used in the light-independent reactions, or the Calvin Cycle, to fix CO2 into organic sugar molecules, such as glucose.