Biofuels are made up of biomass which is an organic renewable energy source. Biomass is converted into biofuel, or energy, through burning, anaerobic combustion, gasification or pyrolysis. Common examples of biomass used for biofuels include wood chips, animal dung, kitchen and garden scraps, municipal garbage and sewage, and plants such as corn and soy. People have used biomass energy—energy from living things – since the earliest cave men who first made wood fires for cooking and keeping warm.
Examples of biofuels include ethanol (often made from corn in the United States and sugarcane in Brazil), biodiesel (from vegetable oils and liquid animal fats), green diesel (derived from algae and other plant sources), biogas (methane derived from animal manure and other digested organic material) and wood.
Not all are created equal.
TYPES OF BIOFUELS
Here are the five fuels ranked from lowest to highest carbon footprint (most environmentally friendly to least), based on their typical lifecycle greenhouse gas emissions.
- Biogas
- What it is: A methane-rich gas captured from the natural decomposition of organic waste in oxygen-free environments.
- How it works: Animal manure, food scraps, and sewage sludge are placed into large, sealed tanks called anaerobic digesters, where microbes break down the matter and release methane and carbon dioxide.
- Key advantage: It prevents potent greenhouse gases from escaping into the atmosphere from landfills and farms, and it can be purified into renewable natural gas (RNG) for home heating or heavy-duty trucks. Of the 5 fuels, it has the lowest overall carbon footprint.
- Disadvantages: Industrial digesters require massive upfront financial investments. The raw gas is heavily contaminated with corrosive elements that require intense purification, and managing compressed methane poses explosion risks.
- Renewable Diesel (Green Diesel)
- What it is: A next-generation, high-performance fuel made from the same biological fats and waste oils used in biodiesel, but processed completely differently.
- How it works: It undergoes hydrotreating(refining the oils with hydrogen under intense heat and pressure), which strips away all oxygen molecules to create a pure hydrocarbon.
- Key advantage: Because it is chemically identical to conventional fossil diesel, it serves as a 100% "drop-in" replacement that requires no engine modifications or blending limits. Additionally, it reduces emission by up to 60% to 85% compared to fossil diesel.
- Disadvantages: The complex refining process makes it much more expensive to produce than fossil diesel. It is also limited by a scarcity of feedstocks like used cooking oil, causing supply bottlenecks.
- Biodiesel
- What it is: A renewable liquid fuel produced from vegetable oils (like soy or canola), recycling waste cooking grease, or processing animal fats.
- How it works: The raw fats undergo a chemical process called transesterification, which reacts the oils with alcohol (usually methanol) to separate glycerin from the fuel molecules.
- Key advantage: It is highly biodegradable, non-toxic, and safely blends with regular petroleum diesel (commonly as B20) to immediately lower a vehicle's carbon footprint. Reduces emissions by roughly 50% to 70% compared to fossil diesel.
- Disadvantages: It can gel and clog fuel filters in cold weather. It also leaves behind trace impurities that can damage fuel injectors, and its demand has driven tropical deforestation for oil palm plantations.
- Ethanol
- What it is: A clear, renewable alcohol fuel made by fermenting the starches and sugars found in plants.
- How it works: Conventional ethanol comes from food crops like corn or sugarcane; advanced cellulosic ethanolbreaks down tough, non-food fibers like wood chips and crop stalks using specialized enzymes before fermentation.
- Key advantage: It blends easily with standard gasoline (such as E10 or E85) to increase octane levels and reduce harmful tailpipe emissions in passenger vehicles. Reduces emissions by 20% to 40% compared to standard gasoline.
- Disadvantages: It contains about 30% less energy per gallon than gasoline, lowering fuel economy. It also absorbs water from the air, which can corrode engines, and using corn strains global food supplies.
- Wood & Biomass
- What it is: The oldest source of energy used by humans, consisting of organic materials like firewood, wood chips, sawdust, charcoal, and agricultural residues.
- How it works: Raw wood is burned directly for heat, or industrial wood waste is compressed under intense pressure into dense, uniform wood pelletsfor clean-burning home stoves and large-scale power plants.
- Key advantage: It provides a highly reliable, continuous source of heat and electricity that does not depend on the weather, unlike solar or wind power.
- Disadvantages: Burning wood releases harmful particulate matter and air pollution. Over-logging can lead to deforestation, and its low energy density makes transporting and storing large, heavy volumes inefficient. About 20% of the energythe EU counts and subsidizes as “renewable” comes from logging and burning forest wood. This increases carbon pollution, destroys forest ecosystems, and adds to air pollution. Burning forest biomass isn’t carbon neutral or even “low carbon” as the idea of “renewable” implies. Leading scientists recognize that regrowing forests to offset CO2 from burning wood takes decades to centuries. Not to mention that per unit of energy, biomass results in higher emissions than coal.
More to learn here: https://solartechonline.com/blog/types-of-biofuels-complete-guide/
AND here: https://www.britannica.com/technology/biofuel
BIOFUEL POLICY
In 2005, The Renewable Fuel Standard (RFS) was established by the Energy Policy Act and upgraded in 2007. In a nutshell, the RFS, which is administered by the Environmental Protection Agency (EPA), required petroleum refiners to add increasing amounts of renewable alternatives into the nation’s transportation fuels. The motive behind the RFS was to reduce greenhouse gas (GHG) emissions, curb America’s addiction to foreign oil, and catalyze the development of new biofuels.
The RFS successfully drove conventional corn ethanol from under 1% of the U.S. gasoline supply in 2005 to virtually 10% across the country. Nearly every gallon of standard unleaded gasoline sold at the pump today is an E10 blend (10% ethanol, 90% petroleum).
More to learn here: https://www.epa.gov/renewable-fuel-standard/overview-renewable-fuel-standard-program
