Plants are living power stations. They turn sunlight into fuel (carbohydrate) that powers our bodies using carbon dioxide and water as the raw materials. The only by-product is oxygen. We eat carbohydrate, breathe oxygen and produce energy, carbon dioxide and water. It is all a big cycle.
Sunlight = Plants = Fuel= Human= Oxygen=by-products= Carbon dioxide and water = Sunlight = Plants = Fuel
Problems arise when we burn fossil fuels. The carbon they stored underground for millions of years once again becomes CO2, increasing levels in the atmosphere, contributing to climate change.
Renewable plant fuels such as wood, energy crops, and biofuels are carbon neutral. Which means CO2 levels in the air will remain the same. These are thus encouraged to be used instead of burning fossil fuels