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The push for drop-in biofuels

Unlike other renewable energy sources (RES), biomass can be converted directly into liquid fuels, called “biofuels”, used mainly for transportation (typically as additive for gasoline or diesel oil), but also for heating and electricity production.


Biofuels play an important role in decarbonizing transport by providing a low-carbon solution for existing technologies, such as light-duty vehicles, in the near term, and heavy-duty trucks, ships, and aircrafts with few alternative solutions, in the long term [1].


Bioethanol & biodiesel


The two most common types of biofuels in use today are bioethanol (alcohol made by fermentation) and biodiesel (produced from new and used veg oils and animal fats via transesterification), both of which representing the 1st gen of biofuels tech [2].  2nd gen biofuels tech, by its hand, uses non-food-based biomass sources such as perennial energy crops and agricultural residues/waste.


Benefits & drawbacks


Biofuels are adaptable to current engine designs, performing fine in most conditions.  Different from solar & wind, and similar to hydroelectricity, biofuels can be stored, and unlike hydroelectricity, biofuels are modular and not location-dependent.


On the other hand, monoculture associated w/ ecological damage, use of fertilizers, water use, shortage of food, and industrial pollution are the main drawbacks of biofuels [3].  Moreover, the average life-cycle surface power densities for biomass, wind, hydro, and solar power production are estimated to 0.30 W/m2, 1 W/m2, 3 W/m2, and 5 W/m2, respectively (power in the form of heat for biomass, and electricity for the others) [4].


Main producers


The U.S. is the leading producer of fuel ethanol in the world, w/ 15 billion gallons in 2021, followed by Brazil, w/ 9 billion gallons in the same year.  They are also the largest biodiesel producers in the world, totaling 6.9 (U.S.) and 6.2 (Brazil) billion liters, respectively, in 2021 [5].




Promising to revolutionize cargo transport, HVO (Hydrotreated Vegetable Oil), a 2nd gen biofuel and the most significant representative of green diesel, is produced by the technological route of hydrotreating vegetable oils (including waste cooking oils) or animal fats.  Given its high calorific value & low emission level, HVO, which grows in the world at much higher rates than ethanol & biodiesel, can be added to mineral diesel at any level, a procedure not contemplated by the biodiesel [6] [7].










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