A Complete Guide to Biofuels and Their Role in Sustainable Energy

Biofuel may sound futuristic, but you are probably already using one without realizing it. Collectively, they hold great promise for reducing fossil fuel dependency, but the situation is nuanced. Here’s what biofuels are, their role in the global energy mix and the challenges you face by powering the world this way.

Powering Vehicles with Biofuel Blends

The most widespread use of biofuels happens at the pump. These renewable fuels are mixed with conventional gasoline and diesel to reduce emissions and stretch petroleum supplies.

Blending with Bioethanol

Bioethanol is a plant-based alcohol fuel produced primarily from corn and sugarcane. It’s blended with gasoline to produce fuel compatible with standard engines. In the United States, more than 98% of gasoline already contains ethanol. 

Here are the main blends you’ll encounter:

• E10: The standard blend contains 10% ethanol and 90% gasoline.
• E15: This blend contains 15% ethanol. It works in newer light-duty vehicles.
• E85: This high-ethanol blend is designed for flexible-fuel vehicles.

Ethanol has a higher octane rating than gasoline, helping prevent engine knocking and improving performance. More importantly, corn-based ethanol, which accounts for 94% of U.S. production, has a positive energy balance. It produces more energy than is required to grow, harvest and process the corn. This makes it a genuinely renewable option.

Blending with Biodiesel

Biodiesel comes from vegetable oils, animal fats or recycled cooking grease. It contains between 10% and 12% more oxygen than petroleum diesel, enabling more complete combustion. This cleaner burn reduces tailpipe emissions by 74% in pure biodiesel, according to the U.S. Department of Energy.

However, biodiesel is usually blended:

• B20: It contains 6%-20% biodiesel mixed with petroleum diesel, which reduces carbon dioxide (CO2) emissions by 15%.
• B5: This lighter blend is 95% diesel and 5% biodiesel.
• Diesel Number Two: While it is not a biofuel, it is often mixed with B5 or B20 to improve cold-weather performance

Replacing Fossil Fuels with Drop-In Biofuels

Blends represent a transitional approach, but drop-in fuels take it further. These biofuels require no engine modifications or infrastructure changes and can be used straight from the pump.

Using Renewable Diesel

Renewable diesel is often confused with biodiesel, since both use similar feedstocks, such as vegetable oils and animal fats. The difference lies in processing. Biodiesel is produced via transesterification, while renewable diesel is produced via hydrotreating. 

Hydrotreating produces a fuel that’s chemically indistinguishable from petroleum diesel and meets the ASTM D975 specification. It can be used in any concentration up to 100% in any diesel engine without modifications. Even better, existing petroleum refineries can be converted relatively easily to produce renewable diesel.

Using Sustainable Aviation Fuel

Aviation is one of the hardest sectors to decarbonize, making Sustainable Aviation Fuel (SAF) particularly significant. SAF is a drop-in replacement that can be blended with conventional jet fuel without requiring any aircraft modifications.

The International Air Transport Association projects that SAF could contribute up to 65% of the emissions reductions needed to reach net-zero emissions in aviation by 2050. That’s not theoretical. Experts already know that SAF is safe, can reduce life cycle carbon emissions by up to 80% and has already powered millions of flight hours.

This alternative fuel can be produced from numerous feedstocks, including waste oils, agricultural residues and municipal solid waste, which helps address scalability concerns.

Generating Energy from Biomass

Biofuels aren’t limited to liquid transportation fuels. Solid and gaseous biomass forms generate electricity and provide heating for homes and businesses.

Creating Power from Solid Biomass

Using wood and plant materials for energy is hardly new, but the scale and efficiency have changed. Modern biomass power plants burn materials such as wood pellets, forest residues and energy crops to generate steam that drives turbines. The process is straightforward combustion, similar to coal plants. Some countries, such as Denmark and Finland, get 14% of their electricity from solid biomass.

Creating Power from Biomass Gasification

Gasification offers a different pathway. Instead of burning biomass, this process converts organic materials into hydrogen and other gases without combustion. It uses temperatures above 1,292° Fahrenheit, steam and a controlled amount of oxygen to transform materials like crop residues, forest waste and organic municipal solid waste into usable fuel.

The climate benefit comes from carbon recycling. The CO2 released through the gasification process is roughly equal to the CO2 the plants absorbed during growth. This creates a closed carbon loop.

A Snapshot of Common Biofuel Types and Uses

A wide range of biofuels are already in use, as this reference table illustrates. 

The Global Landscape of Biofuel Adoption Today

Adoption of biofuels remains uneven globally. Here’s where things stand:

• Bioenergy accounts for 2% of global electricity supply as of 2025. Usage doubled from 2000 to 2018, but has since slowed.
• Global production of liquid biofuels has grown sevenfold in the last 20 years.
• Only 0.4% of aviation runs on biofuel, despite the sector’s decarbonization goals.
• The U.S. and Brazil are the world’s largest biofuel producers by a significant margin.
• Over 90% of the world’s biofuels come from food crops, with corn accounting for more than one-third of the total.
• Bioenergy use is more common in Europe and South America than elsewhere, driven by policies that encourage the switch.

Are Biofuels Truly Environmentally Friendly?

For all their promise, biofuels face legitimate sustainability hurdles. Of the four main challenges, land-use change is the most pressing. Diverting existing farmland from food to fuel can trigger agricultural expansion elsewhere. Clearing forests or peatland to grow biofuel crops releases massive amounts of stored carbon, potentially negating decades of emissions savings.

Food security and prices are also impacted. Relying on feedstocks like corn competes directly with food supplies. When fuel production drives up demand for these crops, food prices can rise and hit vulnerable populations hardest.

Growing biofuel crops at scale strains freshwater supplies, while fertilizer runoff pollutes waterways. Intensive farming practices can degrade soil quality and cause erosion, diminishing long-term agricultural productivity.

The supply of sustainable waste-based feedstocks, such as used cooking oil, is limited. Meanwhile, scaling second-generation biofuels produced from nonfood biomass is proving technologically complex.

Can Algae Solve Biofuel’s Biggest Challenges?

Microalgae are a potential third-generation biofuel source that could sidestep some of these problems. The advantages are compelling on paper.

Algae can be grown in seawater, wastewater or on non-arable land, eliminating the food-versus-fuel dilemma. They also demonstrate a higher photosynthetic efficiency and faster growth rate than terrestrial plants, meaning they produce more biomass in less space.

However, the challenges are equally real. Developing cost-effective harvesting methods remains difficult. Extracting usable fuel from algae remains inefficient, and the high cost of building and operating photobioreactors hinders commercial viability. Progress continues incrementally, but algae-based biofuels remain more of a promise than reality for now.

What Is the Future of Sustainable Fuel?

Biofuels play a complex role in the energy transition. They’re not a perfect solution, but they are delivering real emissions reductions today in sectors that have few other near-term options. The path forward likely involves waste-to-fuel technologies, advances in algae cultivation and policies that incentivize truly sustainable feedstocks. For now, biofuels remain an imperfect but essential part of efforts to reduce dependence on fossil fuels.