Biofuel is climate neutral as plants decompose anyway in the nature every day. During the natural decompose process bound CO2 of the plants are released into the atmosphere. Only if during the decomposing process the organic material is coverred by mude or earth, the CO2 can't be released as oxigen is missing.
For example this is how all cole reservoirs developed. But when a decay happens with the lack of oxygen, also methan (CH4) will be generated which is a minimum of 20 times more climate-damaging as CO2. By producing biofuel out of the plant, we can use the natural, short termed carbon-lifecycle in a energetic way without producing climate damaging gases. Through the new legal obligation to get emission certificates while using fossile fuel, using climate neutral fuel as green energy is also getting more economicly attractive.