This course looks at biofuels, which are sources of energy that come from material that was recently living. This energy is derived from the process of photosynthesis where the plant uses the energy from sunlight to allow it to take carbon dioxide gas from the atmosphere and convert it into sugars and into the carbon containing structures within the plant. These structures can, for instance, be burned to release the energy they contain. Therefore, burning a biofuel releases carbon dioxide that was trapped only a few years beforehand and so is said to be 'carbon neutral', whereas burning a fossil fuel releases both the energy and carbon dioxide that was trapped millions of year before and can lead to global warming. Wood and certain types of grass can be used as biofuels. Plants that contain large amounts of sugar or oil can be used to produce bioethanol or biodiesel, which are important transport biofuels.
This OpenLearn course provides a sample of level 1 study in Science [Tip: hold Ctrl and click a link to open it in a new tab. (Hide tip)]