Biofuel is a renewable energy source that is made from organic materials such as agricultural waste, wood, or biogas. And, is often used as a replacement for fossil fuels such as gasoline and diesel, due to its low environmental impact. Biofuel is also known as second-generation biofuel, as it is derived from processed bio-based products such as bio-diesel or bio-ethanol. Biofuel is currently used in a variety of ways, including transportation, heating, and industrial processes. In this post, we will discuss the different types of biofuel; the extent of production and use, and the environmental impact of biofuel. Biofuel production is growing rapidly as a way to reduce environmental impact and improve energy security. Biofuel can help reduce greenhouse gas emissions, and it can play a role in addressing global climate change.

Generations of Biofuel

Depending upon the type of biomass feedstock utilized for biofuel production generation of biofuels changes.

First generation: Biofuel was made from food crops, which have always been debated as crops for food or fuel. This generation of biofuel was never found to be sustainable and was not very practical. Today, we have more affordable and practical biofuels made from different types of plants.

Second generation: Biofuel is made from plant materials that are not food crops. This type of biofuel is called cellulosic biofuel or second generation of biofuels. The biomass feedstock utilized here is mostly agricultural residues, grasses, or other plants. Using chemical and enzymatic biomass degradation technologies, this agricultural residue is digested to produce mono-sugars. In subsequent stages of fermentation technology, these mono sugars are utilized by fungal and yeast species to produce bioethanol. Apart from this, all fresh biodegradable biomass is also utilized to produce biomethane called biogas by anaerobic fermentation technology. Further, this gas is purified to generate pure grade (>95) methane called Compressed Natural Gas (CNG), which has practical applications as automobile fuels and is also used in domestic applications and also to produce electricity.

Third generation: The third generation of biofuels is a futuristic avenue of biofuel industries. This includes the use of advanced fermentation technologies where microbial cells that are genetically modified will produce biofuels in the fermentation broth. This broth can be easily processed to recover produced biofuel and will be ready to use for its final utility. Examples of such technology include the use of photosynthetic microalgae and dinoflagellate species that have the potential to produce fatty acids that can be easily transesterified to produce biodiesel.

Examples of Basic Biofuel

Types of biofuel: bioethanol, biodiesel, and biogas.

Bioethanol is made from biological sources, such as corn, sugar cane, or wheat. The processes used to produce ethanol are enzymatic digestion (to release sugars from stored starch), fermentation of sugars, distillation, and drying. The distillation process inputs a large amount of energy for heat.

Biodiesel is made from vegetable oils and animal fats. Biodiesel, when mixed with mineral diesel, can be used in all diesel engines and modified equipment. It can also be used in diesel engines in its pure form (B100), but this can lead to winter maintenance and performance problems as the fuel is slightly viscous at low temperatures, depending on the raw materials used.

Biogas is made from organic waste, such as food scraps, manure, and sewage. Biogas is primarily composed of methane (CH4) and carbon dioxide (CO2) and may contain small amounts of hydrogen sulfide (H2S), water, and siloxanes. The gases methane, hydrogen, and carbon monoxide (CO) can be burned or oxidized with oxygen. This release of energy allows biogas to be used as fuel. It can be used for any heating application such as fuel cell or cooking. It can also be used in gas engines to convert gas energy into electricity and heat.

Examples of extended categories of Biofuel from basic ingredients:

This category of biofuels involves the use of basic biofuel/biochemical produced from biological origin to convert into modified fuels as suitable blending formulations with conventional fossil fuels. These products can be used even as an individual fuel with necessary modifications in the existing automobile engine technology. Following some examples of extended categories of biofuels will give an idea about biofuels in conventional fuels.

Syngas

Syngas is a mixture of carbon monoxide (CO), hydrogen (H2), carbon dioxide (CO2), and sometimes other trace gases. This is produced through the gasification of biomass, and can also be produced from hydrogen and carbon dioxide through electrolysis. It is used as a substitute for natural gas and petroleum and is often used in the production of industrial chemicals, and synthetic fuels. Syngas can also be used to generate electricity via a gas turbine or fuel cell. Syngas has several advantages over other fuel sources. It is very efficient and produces fewer emissions than traditional fossil fuels, and produces fewer pollutants than natural gas.

Pyrolysis of biomass produces oil:

Pyrolysis of biomass is a fast and efficient way of producing oil. In this process, biomass such as wood, grass, and agricultural wastes are heated in the absence of oxygen under very high pressure, breaking them down into smaller molecules. This process results in the production of volatile gas and two liquid fuels, namely, light oil and heavier, more viscous oil. The oil produced is similar to diesel fuel and can be used in engines, furnaces, and boilers. It is also an important source of renewable energy and can be used to produce biofuels, such as biodiesel. Pyrolysis of biomass is an important process that can help reduce the production of greenhouse gases, as it does not involve burning fossil fuels, and the by-products can be used to produce renewable energy.

Hydrogen:

Hydrogen biofuel is a clean-burning fuel that produces no harmful emissions when burned. It is considered to be the ultimate renewable energy source since it can be produced from water with the use of renewable energy sources such as solar, wind, and hydroelectric.

The process utilized and researched in hydrogen production is: Hydrogen production using solar cells is the process of using solar energy to generate hydrogen from water. This process is known as water splitting, and it involves separating hydrogen from oxygen in water molecules.

The alternative approach also utilizes methane gas for hydrogen production which is typically achieved through a process known as steam methane reforming (SMR). This process involves the reaction of methane (CH4) with high-temperature steam (H2O) over a catalyst, usually, nickel, to produce hydrogen (H₂) and carbon dioxide (CO₂). The chemical reaction can be expressed as follows:

CH₄ + H₂O → CO₂ + 3H₂

Hydrogen can be used to power a variety of vehicles, from passenger cars to buses, trains, and boats. Also, be used to produce electricity in a variety of ways, such as through fuel cells, thermochemical processes, and electrolysis. Hydrogen biofuel has a higher energy density than other biofuels, making it a very efficient source of energy. It can be used in existing internal combustion engines without any modifications, making it a great option for transportation. It is also a great option for powering stationary applications such as generators and stationary power plants. Hydrogen biofuel has the potential to revolutionize the way we power our vehicles and reduce our dependence on fossil fuels.

Bioether:

Bioethers are an efficient and environmentally friendly alternative to traditional petroleum-based ethers. They provide octane-enhancing properties while reducing engine wear and emissions of air pollutants. Bioethers are produced from renewable sources like wheat or sugar beets and are becoming increasingly popular in Europe, while the U.S. is phasing out the use of MTBE and ETBE as fuel oxygenates. Bioethers are not likely to become a fuel in and of themselves due to their low energy density, but their contributions to the reduction of ground-level ozone emissions make them an essential part of the transportation fuel landscape.

Biogasolin:

Biogasoline, also known as green gasoline, is a renewable biofuel made from plant sugars and other non-food materials. Biogasoline is produced using biotechnology processes that allow the conversion of glucose from plants or other non-food sources into hydrocarbons that are chemically and structurally identical to those found in commercial gasoline. Professor Lee Sang-yup and his team made use of modified Escherichia coli bacteria to produce the biogasoline, demonstrating the potential for bio gasoline to reduce our reliance on fossil fuels and make use of renewable sources of energy. The biogasoline produced in this study has the same energy density as commercial gasoline and can be used as a direct fuel substitute. Biogasoline is a promising renewable fuel that could help to combat climate change (Jang, Y. S. et al. 2012).

Methyl tert-butyl ether (MTBE):

MTBE is manufactured by the chemical reaction of methanol and isobutylene. Methanol is primarily derived from natural gas, where steam reforming converts the various light hydrocarbons in natural gas (primarily methane) into carbon monoxide and hydrogen. The resulting gases then further react in the presence of a catalyst to form methanol. Isobutylene can be produced through a variety of methods. One process involves the isomerization of n-butane into isobutane, which then undergoes dehydrogenation to form isobutylene. In the Halcon process, t-Butylhydroperoxide derived from isobutane oxygenation is reacted with propylene to produce propylene oxide and t-butanol. The t-butanol can be dehydrated to isobutylene.

On blending with petroleum, MTBE increases octane and oxygen levels in gasoline and reduces pollution emissions. Because of concerns about groundwater contamination and water quality, MTBE has now been banned or restricted in several countries. MTBE is also used in small amounts as a laboratory solvent and for some medical applications.

Positive Impact of Biofuel on the Environment, Society, and Economy

Environmental: Biofuels are carbon-free fuels derived from organic and renewable resources. They do not create pollution on combustion, which will help to reduce the climate change effect if implemented on a larger scale. Even with existing fossil fuels appropriate blending of biofuels has proved to be exerting positive environmental impacts.

Social: Biofuel technology will help to develop indigenous business models for the production of its own renewable fuel depending upon the resources available in each country. This will also help to reduce the reliance on the foreign supplier for the fuels. This will help to boost the economy of the individual countries by promoting export, business development, employment, and good transportation systems with novel biofuel resources.

Economic: Worldwide production of fossil fuels is reducing due to their limited resources. This is increasing the cost of fuel day by day. Biofuel substitution in fossil fuels will help to curtail a large number of economic losses. Biofuels will help to develop alternative energy sources along with sustainable development.

Conclusion:

The exhausting conventional energy resources have also developed environmental concerns. In the last few decades, the need for clean energy resources has received the necessary importance to tackle the issue of climate change. Non-conventional energy resources like tidal, wind power, solar, hydro, and geothermal are some of the best sources for renewable energy generation but lacking technological interventions make this task difficult. Biofuels would prove to be the best alternative sources of energy for the future. They are absolutely renewable, non-polluting, and possibly cheaper than fossil fuels and they have many benefits in long run. Therefore, biofuels are now considered a fuel of the future. The next few decades will decide the fate of these energy sources depending upon their development and implementation. 

References:

Jang, Y. S., Park, J. M., Choi, S., Choi, Y. J., Cho, J. H., & Lee, S. Y. (2012). Engineering of microorganisms for the production of biofuels and perspectives based on systems metabolic engineering approaches. Biotechnology advances, 30(5), 989-1000.