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Biofuels

Fast Facts About
Biofuels

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Principal Energy Use: Transportation
Form of Energy: Chemical

Biofuels are an energy currency derived from renewable biological sources, such as plants, algae, and organic waste materials. They can replace fossil fuels like gasoline and diesel. 

Biofuels are considered a part of the broader strategy to reduce greenhouse gas emissions and dependence on finite fossil fuel resources. However, current feedstock use and production methods raise debates and concerns related to their environmental impact, land use, and competition with food production that are yet to be solved with more sustainable biofuel production. 

First-generation biofuels are biofuels produced from feedstocks that are primarily food crops or crops specifically grown for fuel production. The main types of first-generation biofuels include:

  1. Biomass-based ethanol (also called bioethanol): Produced by fermenting the sugars from crops like corn (maize), sugarcane, and wheat. It’s the most widely used biofuel and is often blended with gasoline. It can only be blended with gasoline up to 10% (E10) without requiring a special vehicle (flex-fuel).
  2. Biodiesel: Produced from vegetable oils (such as soybean, rapeseed, and palm oil) and animal fats. It can be blended with traditional diesel up to 20% (B20) in regular diesel engines.

First-generation biofuels have important drawbacks, including competition with food crops and land use change. Additionally, they have tradeoffs between the energy they provide, the land they require, and the emissions they help avoid, and these factors can vary depending on crop type, production methods, and transportation. In some cases, they can have a larger carbon footprint than their fossil fuel counterparts.

Because of these concerns, there has been an effort to shift toward second-generation (also called advanced) biofuels that are produced from non-food feedstocks, such as agricultural and forest residues, algae, municipal solid waste, and grasses that can grow on hillsides and won’t compete with food crops. Examples include:

  1. Renewable diesel: Produced from vegetable oils and animal fats. It’s categorized as second generation because it can be produced from used cooking oil and other non-food waste streams. It’s chemically identical to petroleum diesel and can be used in existing diesel engines (a “drop-in fuel”). Renewable diesel adoption is growing rapidly, especially in California, due to the state’s Low Carbon Fuel Standard.
  2. Cellulosic ethanol: Produced from agricultural and forestry residues, grasses, and other waste streams like paper. Cellulosic ethanol is more energy intensive, expensive, and technologically challenging to produce, limiting its growth.

Biofuels are mainly used for transportation, but they are a very small contributor to transportation energy. Demand for biofuels is expected to grow in the next five years due to climate goals and policy mandates.  Visit our Gasoline, Diesel, Jet Fuel, etc. page for more information about transportation fuels.

Significance

Energy Mix

1% of world 🌎
2% of U.S. 🇺🇸

95% of Biofuel Use Is for Transportation

4%
of global transportation energy comes from biofuels

Types of Biofuels

Ethanol 64%
Biodiesel 27%
Renewable Diesel 8%
SAF* 0.1%
of global biofuel production

*Sustainable Aviation Fuel (SAF)

Biofuels Demand

Increase:
⬆ 27%
(2018-2023)

Ethanol

World

Example Impacts of Using Food Crops for Ethanol
  • Competition for arable land and resources between food production and fuel production can lead to food price increases and food security issues.
  • Fertilizer use can contribute to soil and water pollution. In the Gulf of Mexico, fertilizer runoff from the corn belt in the U.S.—driven partly by increased ethanol production—has contributed to the “dead zone”, a low-oxygen zone that harms fish and marine life near the bottom of the sea.

Fun Fact

Ethanol (also called ethyl alcohol) is the same type of alcohol found in drinks like vodka and whiskey, but fuel ethanol is denatured, meaning chemicals are added to make it unsafe to consume. Without denaturing, fuel ethanol would be taxed and regulated like liquor, making it far more expensive to produce and sell. And we also don’t want people drinking fuel!

Largest Producers

U.S. 52% 🇺🇸
Brazil 28% 🇧🇷
of global ethanol production

Largest Consumers

U.S. 50% 🇺🇸
Brazil 26% 🇧🇷
of global ethanol consumption

Highest Penetration

Brazil 28% 🇧🇷
of country’s transportation energy comes from ethanol

Ethanol Mandates

Brazil 27% 🇧🇷
Paraguay 25% 🇵🇾
Norway 20% 🇳🇴
of gasoline must be blended with ethanol

Corn vs Sugarcane for Ethanol Production

In the U.S., ethanol production is mostly from corn because that’s what the U.S. grows. In Brazil, it is mostly from sugarcane. Sugarcane is a far more efficient energy crop, yielding 590 gallons of ethanol per acre compared to 370-430 gallons from corn. In U.S. federal policy and California’s Low Carbon Fuel Standard, sugarcane ethanol meets a more stringent renewable fuel standard for having a lower carbon footprint than corn ethanol. This has led to an unintended consequence of the U.S. exporting corn ethanol to Brazil and importing sugarcane ethanol from Brazil.

U.S.

Largest Producer

Iowa 27%
of ethanol produced in the U.S.

Largest Consumers

Texas 11%
California 10%
of ethanol consumed in the U.S.

Highest Penetration

New Hampshire 9%
of transport energy is ethanol

Biodiesel

World

Example Impacts of Biodiesel Feedstock Production
  • Conversion of natural ecosystems or forests into agricultural land for biofuel crops can result in deforestation and habitat loss, with associated environmental impacts.
  • In Indonesia, the expansion of palm oil plantations for biodiesel, food products, detergents, and cosmetics has been an important driver of deforestation, accounting for one-third (30,000 sq km) of its old-growth forest loss and contributing to climate change and biodiversity loss—in particular, orangutans and their habitat.
  • In Brazil, the area dedicated to soy cultivation for use by the food, pharmaceutical, and biodiesel industries has increased 52% in the past 10 years. This is linked to deforestation and agricultural intensification (increased use of fertilizers and pesticides, mechanical tilling, etc.), which is associated with negative changes in food provision and water and soil quality.
Largest Producers

Europe 27%
U.S. 25% 🇺🇸
of global biodiesel production

Largest Consumers

U.S. 23% 🇺🇸
Indonesia 19% 🇮🇩
of global biodiesel consumption

Highest Penetration

Sweden 22% 🇸🇪
of country’s transportation energy comes from biodiesel

Biodiesel Mandates

Indonesia 35% 🇮🇩
Nigeria 20% 🇳🇬
Costa Rica 20% 🇨🇷
of diesel must be blended with biodiesel

U.S.

Largest Producer

Iowa 23%
of biodiesel produced in the U.S.

Largest Consumers

California 14%
Texas 11%
of biodiesel consumed in the U.S.

Highest Penetration

Minnesota 4%
of transport fuel is biodiesel

Renewable Diesel

World

Largest Producers

U.S. 43%
E.U. 30%
of global renewable diesel production

*Remaining production is primarily in Asia, but is shipped to Europe.

Largest Consumers

U.S. 70%
of global renewable diesel consumption

U.S.

Most Production Capacity

Louisiana 51%
of renewable diesel production capacity in the U.S.

Largest Consumer

California 97%
of total renewable diesel consumed in the U.S.

Highest Penetration

California 8%
of transport energy is renewable diesel

Spotlight on Sustainable Aviation Fuel

Globally, aviation is responsible for around 4% of total climate impact. In the U.S., aviation makes up 3% of total emissions and 10% of transportation emissions, with levels expected to double by 2050.

Sustainable aviation fuel (SAF) is a liquid hydrocarbon jet fuel made from renewable or waste resources (like fats, oils, and greases). Many experts are pointing to SAF as a way to decarbonize medium- and long-haul commercial aviation, which produce 95% of aviation GHG emissions and are currently hard to electrify due to battery weight. The carbon footprint of SAF will vary widely based on the feedstock and production process used. 

Research and development efforts are focused on making a SAF that is a 100% drop-in fuel, compatible with today’s aircraft and fueling infrastructure. Currently, SAF can only replace ~10-50% of fossil jet fuel in a plane’s tank. 

SAF makes up <1% of global aviation fuel, and slightly more than 0.1% in the U.S.

Key barriers to SAF include limited feedstock, no carbon price in many regions, and high production costs.

Drivers

  • Global and national policies, such as tax incentives and renewable fuel standards, encourage the production of biofuels as part of their GHG reduction strategies
  • Semi-renewable source of energy if resources are managed sustainably
  • Energy diversification by reducing reliance on oil and helping mitigate energy price volatility
  • Energy security by incentivizing domestic production and reducing reliance on foreign oil
  • Rural development; production of biofuels can support economic opportunities in rural areas
  • Technological advances that have improved the efficiency and cost-effectiveness of biofuel production

Barriers

  • Net-carbon impact is unclear; some biofuels increase GHG emissions compared to fossil fuels
  • Policy and regulatory uncertainty affects investment and development
  • Air pollution challenges still exist
  • Competition with agricultural land and resources for food crops affects feedstock availability and food security
  • Planting single crops (monoculture) degrades soil and reduces biodiversity
  • Large land-use requirements that lead to deforestation and habitat loss
  • Use of pesticides and fertilizer harms water quality
  • Can require lots of water usage
  • Volatility of biofuel feedstock prices
  • Global trade barriers
  • Need for blending with fossil fuels and/or modification of engines for first-generation biofuels
  • Lower fuel demand as EV sales increase
  • Second-generation biofuels face challenges related to scaling up production, cost competitiveness with fossil fuels, and the development of efficient conversion technologies

Climate Impact:
Low to Medium

  • Possibly carbon neutral, but bioenergy crops have different energy yields, and some crops require significant energy inputs, reducing their carbon savings
  • Land use change such as deforestation or conversion of peat swamps to fuel crops releases carbon dioxide and methane

Environmental Impact:
Medium to High

  • Does not improve air pollution: vehicles burning biofuels still emit harmful air pollutants
  • Bioenergy crop production may induce deforestation; in Southeast Asia, rainforests were converted to palm oil plantations to feed the EU’s demand for biodiesel
  • Agricultural processes can impact soil, water resources, and local biodiversity

Sources

 

Updated June 2025

Our 10-Minute Take On
Biofuels

If you're short on time, start by watching this video of key highlights from our lecture on Biofuels.

Diana Gragg

Presented by: Diana Gragg, PhD; Core Lecturer, Civil and Environmental Engineering, Stanford University; Explore Energy Managing Director, Precourt Institute for Energy
 

Recorded: September 5, 2025  
Duration: 13 minutes

Slides available upon request.

If you liked this video, watch the other 10-Minute Takes here!

Before You Watch Our Lecture on
Biofuels

We assign videos and readings to our Stanford students as pre-work for each lecture to help contextualize the lecture content. We strongly encourage you to review the readings below before watching our lecture on Biofuels. 

Essential

Optional

Our Lecture on
Biofuels

Our Stanford University Understand Energy course lecture on Biofuels is the last section of our Biomass for Energy lecture. We strongly encourage you to watch the designated lecture section below to understand the role of biofuels in our energy system and to be able to put this complex topic into context. For a complete learning experience, we also encourage you to review the Essential readings we assign to our students before watching the lecture.

Diana Gragg

Presented by: Diana Gragg, PhD; Core Lecturer, Civil and Environmental Engineering, Stanford University; Explore Energy Managing Director, Precourt Institute for Energy
Recorded on: November 19, 2025   Duration: 24 minutes

Table of Contents

(Clicking on a timestamp will take you to YouTube.)

Biomass Lecture

50:53 Biofuels: Introduction and Significance 
58:27 Ethanol 
1:04:44 Biodiesel and Renewable Diesel 
1:05:58 Biofuel Sources 
1:07:04 Incentives and Standards 
1:13:38 Sustainable Aviation Fuels 
1:14:16 Summary of Biofuel Concerns

Lecture slides available upon request.

Additional Resources About
Biofuels

Next Topic: Hydrogen Other Energy Topics to Explore

Fast Facts Sources

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