Biofuel Definition And Examples
Biofuels are considered a green alternative to fossil fuels because they are produced from recently living organisms, and not from organisms that lived millions of years ago.
What Is Biofuel?
Biofuel is mainly produced from plants and algae only because these organisms have used photosynthesis during their life on the planet, which uses the sunlight to synthesize nutrients in water and carbon dioxide.
By storing the Sun’s energy during their entire life on the planet, plants and algae have now become a good source of carbon neutral energy, so when we use them in engines with internal combustion, we are no longer polluting the environment because the carbon released returns in the carbon cycle of the planet (is not produced extra like the carbon produced by fossil fuels).
Animal waste is also used to produce biofuels, but this is often done at a much lower scale.
Due to the fact that biofuels are produced from plants, algae, and organic waste, they are considered a renewable resource because plants, algae and organic waste can be produced over and over again.
Examples of Biofuel
The term ‘biofuel’ is used to describe carbon neutral fuels produced from biomass. The most common types of biofuels known today are ethanol, biodiesel and bio-jet-fuel.
These biofuels represent a cleaner alternative to conventional fuels like gasoline, diesel and jet fuel.
Based on the type of feedstocks used to produce biofuels, we have: first generation biofuels, second generation biofuels, third generation biofuels and advanced biofuels.
First generation biofuels use feedstocks such as food crops like corn, sugar cane and maize for ethanol production, and vegetable oils from soybean and canola for biodiesel production and Jatropha, Babassu and Camelina for bio-jet-fuel production.
Second generation biofuels are produced from cellulosic materials such as wood, grasses, and the inedible parts of the plants.
Being more difficult to break down through fermentation, cellulosic materials require a pretreatment before they are processed for biofuel production.
Third generation biofuels are produced using lipids from algae (biodiesel and bio-jet-fuel).
Advanced biofuels refer to a relatively new tehnocologial field used to produce biofuels from waste (animal waste and garbage), animal fats and used cooking oil for liquid fuels like biodiesel.
1. Ethanol
Ethanol is an alcohol produced from corn through a process called fermentation.
This is a simple biological process using sophisticated techniques and equipment.
The ethanol production from corn starts with the corn seeds that are ground to obtain a fine granular consistency.
Water and enzymes are added to the starch matter obtained this way.
The mixture of corn, water and enzymes is called mash and is heated to a temperature around 185°F (85°C), where the mixture starts to break down into fermentable sugars.
When yeast is added, the mixture is cooled to a temperature around 92°F (33°C). The yeast will consume the sugars (a process called fermentation). When the yeast ferments, carbon dioxide is released, and the sugars are converted into alcohol.
The fermentation process takes between 52 and 62 hours, and once the yeast has finished its job, the resulting mixture called ‘beer’, contains about 17 to 18% alcohol by volume.
The beer is then pumped from the beer well to the distillation column where heat is added. The alcohol exits the column at a concentration of 95% alcohol vapor.
In the next phase, the alcohol vapor moves to a second distillation stage, and further distills to 195 proof alcohol.
The alcohol vapor passes through a condenser, which turns the vapor into liquid.
Once in liquid form, the alcohol passes through a molecular sieve process, to extract the remaining water.
This is how the final ethanol product is obtained, which is 200 proof and 99% alcohol.
From the production facility, ethanol is transferred to storage tanks and then are loaded under rail cars for shipment.
2. Biodiesel
Biodiesel is a biofuel produced from plant oils, animal fats and used cooking oil.
When cooking oil is the feedstock
When produced from used cooking oil, the oil coming from restaurants is transported to a filtering plant. There, is pumped into a holding tank, then heated up to dry out the water.
Once the water is drained, the oil is ready to enter a multi-stage filtering process.
First, the oil goes through a vibrating sieve, which retains the larger pieces of debris. After the first filtering, the oil is passed through a second vibrating sieve that can catch smaller particles of debris.
After the second filtering stage, the oil is cleaner, but still contains microscopic debris, so it enters the third and final filtering stage.
In this stage, the oil will pass through twenty ultrafine filter cloths that trap any particle larger than one micron in size.
Once filtered, the used cooking oil is ready to become biodiesel.
When the feedstock consists of animal fats
The main feedstock used in this case is cow tallow, or other animal fats coming from butcheries. The fat shredded from the back of the cowhide drops onto a conveyor, which moves it into a steam injection cook tank.
Inside the tank, the fat is heated to a gentle boil in order to extract the oil. What remains, leaves the tank and drops into a waste container.
The oil extracted moves forward passing through a two-stage filtration process similar to the one filtration process used to clean used cooking oil.
Biodiesel Production
The feedstock oil produced from used cooking oil or animal fats is combined with methanol (a type of wood alcohol) and a catalyst that triggers a chemical reaction.
A process unit mixes everything thoroughly while applying heat and pressure. After the chemical reaction a byproduct called glycerin (a common ingredient in soaps and cosmetics) is produced.
In the process, much of the methanol is consumed, so the finished biodiesel will contain only a tiny percentage of it.
To ensure that the biodiesel produced meets international regulatory standards, the plant’s quality control lab tests samples from each production run.
In the flammability test, biodiesel is heated to 275°F (135°C), then a flame is applied to see whether the gasses ignite. In case they ignite, the more methanol needs to be removed to make the biodiesel safe.
When the gases no longer ignite, the biodiesel meets international safety standards.
Biodiesel is more expensive at the pump than regular diesel, but emits significantly less carbon monoxide and dioxide, and 85% less cancer-causing agents.
3. Bio-jet-fuel
Bio-jet-fuel can be produced from a wide variety of feedstock such as: lignocellulosic biomass (wood waste, straw or energy crops like Jatropha and Camelina), waste oils and fats (both animal and vegetal), algae and halophytes, and from biomass containing sugars.
Wood waste for biofuel production, image source: pixabay.com
Bio-jet-fuel Production
The production process of bio-jet-fuel consists of four different stages.
In the first stage, biomass is crushed, dried and preconditioned to obtain a powder that can be injected into a gasifier.
In the second stage (gasification stage) the solid matter is transported to a second site where is heated at a very high temperature in the presence of oxygen in a flow gasifier. This operation turns the solid matter into synthesis gas that must be of high purity to be transformed into liquid fuel.
In the third stage (purification stage), the synthesis gas is washed using solvents and catalysts.
The the fourth and final stage, also called conversion stage, the Fischer-Tropsch synthesis is used. This catalytic operation converts the purified synthesis gas into a liquid hydrocarbon mixture.
The combination of these processes, makes it possible to produce bio-jet-fuel that is friendly with the environment.
Bio-jet-fuel can be used alone, or combined with kerosene.
What Is The Most Common Biofuel?
The most common biofuels use today on a large scale are ethanol and biodiesel.
They represent first generation biofuels because they use as feedstock crops such as: corn, sugar cane and maize for ethanol production, and vegetable oils from soybean and canola for the production of biodiesel.
What Are 4 Biomass Examples?
The main examples of biomass consist of four main types: wood waste and agricultural products (including energy crops), solid waste, landfill gas and biogas.
Conclusion
Biofuels represent a clean alternative to fossil fuels, and we should use them on a much larger scale on the planet, because only this way we can reduce the amount of greenhouse gas emissions released by the transportation sector.
