Green energy is the energy that comes from plants.
A vegetable full of energy?… Don’t be taken in by appearances!
Many plants are real little factories for the manufacture of chemical energy from the light energy emitted by the sun. Using the process of photosynthesis, plants that contain chlorophyll are capable of synthesising sugars from carbon dioxide (CO2) in the atmosphere and water, with a little helping hand from the photons in sunlight.
We can use plant energy in two ways:
By burning wood;
By producing car fuels from certain plants; these are the biofuels.
Plant energy is called biomass. Some experts feel that biomass also includes
the transformation of waste into energy
Biomass is a renewable energy source: plants that are burnt and transformed into fuel are renewed by re-growth or replanting. We can assume that the quantity of carbon dioxide discharged when the plants are burnt is the same as that necessary for their subsequent renewal. The net discharge of greenhouse gases by the biomass is therefore limited to CO2 and other gases discharged in the activities of harvesting, packaging, transporting and transforming the plants used.
This means that biomass fuels are a lot cleaner than fossil fuels.
However the yield from photosynthesis is very low, of the order of 1 to 3% of the solar energy received, depending on the type of plant and the latitude. The biomass is therefore an energy source that takes up a lot of space. And it also uses a lot of water. |