Biomass and biofuels is a type of renewable energy that can be used for the generation of electricity and heat. There are different applications of biofuels. The production technology of these alternative fuels allows to create different products.
The problem of the convenience of feeding with alternative fuels to those that originate from fossil oil is that, in motor fuels, all states in the world impose high taxation. However, biofuels must be considered as non-renewable energy because the generation and recovery time of the fields is lower than the consumption time.
A component of biomass are solid biofuels, of which there is a wide variety of firewood, charcoal, pellets, chips, sawdust and bagasse (for example, cane or agave), as well as agricultural residues (such as peel). coconut, coffee or rice, among others).
Next, we analyze the main liquid biofuels.
The feeding of a diesel vehicle directly with a seed oil causes faults in the injection system and in the engine, due to the carbon deposits in the injectors and the dissolution of the rubber parts. For example, rapeseed oil in the engine can cause crushing and breakage, especially in injectors and high-pressure pumps. Depending on the diesel engine used, it is technically possible to mix 5 to 30% diesel oil in the winter season and 30 to 70% in the summer.
The problem is that biodiesel and even more unesterified oil must enter the engine at higher temperatures than fossil fuel and, in any case, reduce the efficiency of the engine, having a calorific value per liter slightly lower than that of fossil oil . Obviously, this applies to diesel engines currently in use in motor vehicles, optimized to the maximum for fossil fuel, while Rudolf Diesel invented and studied his own engine to operate vegetable oil without special treatments.
Bioethanol is a biofuel that can be added to gasoline, with a percentage that can reach 20%. If technical modifications are made to the engine, it is possible to achieve even 100%. The use in higher percentages occurs in the synthesis of ETBE, an organic derivative. This derivative is used in a mixture with gasoline to replace tetraethyl lead or aromatic hydrocarbons.
In Brazil, a well-known automotive group (General Motors) sells vehicles that can be used either bioethanol, gasoline or methane. This experiment seems to have demonstrated the possibility of producing bioethanol, at competitive costs compared to the market price of gasoline.
Methanol has multiple industrial applications, the main ones being the use as a solvent for fats (in replacement of toxic and carcinogenic trichlorethylene), oils, resins, cellulose nitrate, dyes and antifreeze solutions. Methanol for transportation seems to be a comparable fuel, for the yields and vehicles used, to traditional gasolines; It can also be used in the production of biodiesel.
Methanol, derived from fossil fuels, is a synthetic gasoline, used for example in races in Indianapolis, characterized by a higher octane number than gasoline. In theory, methanol could, therefore, be used as pure fuel for motor vehicles.
Actually, to do this, it would be necessary to intervene to guarantee the cold start of the engine and the use of materials resistant to corrosion caused by alcohol. However, in Europe there are still no large-scale applications of engines that run on pure biomethanol. The main disadvantages that limit the use of methanol as a biofuel refer to its storage and transportation, which is particularly expensive.
Biodiesel, pure or mixed in various proportions, can theoretically be used in modern diesel engines, even if problems of clogging have been found in the vehicle's fuel system in the past due to the dissolution of the rubber parts, caused to turn for more power. Biodiesel solvent compared to traditional diesel. Biodiesel blends up to 5% do not cause problems and are usually marketed in many European countries. The vehicle warranty, for many car manufacturers, meets a blend of up to 30% biodiesel and 70% diesel.
The internal energy of biodiesel is mainly used in the following applications:
- Biodiesel for cars (diesel engines) either pure (in recent diesel engines) or mixed with diesel.
- Biodiesel for heat and energy production. This thermal variant is a clear competition with solar thermal energy, a source of renewable energy. For heating it can be used pure or mixed with diesel in any proportion.
Other lines of recent research related to biofuels have attracted the attention of the academic and industrial world: the production of biodiesel from microalgae crops.
From cellulosic materials, the production of hydrogen by biological means. Microalgae are unicellular photosynthetic organisms that can live in fresh, brackish or salty waters, include a wide variety of species adapted to very different conditions and have the ability to multiply rapidly and reach higher biomass densities than terrestrial plants; in addition, they do not interfere with agricultural production dedicated to food. They offer the possibility of producing:
- Biodiesel, from microalgae rich in oil, through the transesterification process;
- Bioethanol, from microalgae rich in carbohydrates, through the fermentation process.
Biotechnology in the future will surely lead to a more efficient production of biofuels and biofuels. For example, the production of a diesel fuel not only of biological origin, such as biodiesel, but also obtained with biotechnological processes, could change future prospects by introducing a fully organic production diesel produced biologically / biotechnologically.
Last review: July 15, 2019