The burning of biodiesel, as with all biofuels, produces about the same amount of CO2 that is produced by the burning of conventional fuels. However, this quantity is equal to the quantity of CO2 absorbed from the atmosphere by the plant from which biofuels are derived. Thus, the CO2 balance from the growth of the plant and the burning of the biodiesel produced is zero. This sustainability, however, is affected by the CO2 emitted into the atmosphere throughout the cycle of biofuel production, that is, from the exhaust gases of agricultural machinery used for the cultivation and harvesting of raw materials, the production of fertilizers, their transport, etc. As a result, the reduction of CO2 in relation to conventional fuels is not 100% but fluctuates between 50% and 90%.
In the case where waste materials, such as used cooking oil and animal fat, are used, the lifecycle reduction reaches or surpasses 90%. The environmental benefit is double-sided, one being the obvious, i.e. less greenhouse gas emissions, the other being the recycle of waste materials, which in any other case would have been disposed to the environment.
That is the main reason why the use of biodiesel from waste materials is strongly encouraged by the EU and the quantities of it that are used as motor fuel count as double in the member states’ obligation to meet their biofuel targets.
