The conversion of carbon dioxide into carbohydrates - the process of photosynthesis as carried out by plants - is an uphill thermodynamic process, with the energy provided by the sun. The reduction of...The conversion of carbon dioxide into carbohydrates - the process of photosynthesis as carried out by plants - is an uphill thermodynamic process, with the energy provided by the sun. The reduction of CO 2 to methane by hydrogen gas (H 2 ), for example, is a thermodynamically downhill process, because H 2 is a such a powerful reducing agent. When you see bubbles of 'swamp gas' (methane) rising from the mud of ponds and rivers, you are looking at the result of methanogenesis.
