Intermediate Topic 402 of 1102 Thermodynamics & Energetics
Biofuels
Renewable fuels such as ethanol and biodiesel derived from biomass.
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In-depth explanation of Biofuels
Biofuels are fuels produced from recently living biomass rather than ancient fossil deposits. Examples include bioethanol, made by fermenting sugars from crops such as sugarcane or maize, and biodiesel, made by transesterification of plant or animal fats with methanol. Because the carbon released on burning was recently taken up from the atmosphere during growth, biofuels are considered nearly carbon-neutral over their full cycle, although fertilizer and processing emissions reduce this benefit. They compete with food production for land and water, which raises ethical and environmental questions. Biofuels can be blended with gasoline or diesel for use in existing engines.
Going deeper: Biofuels
Key ideas: Ethanol comes from fermentation of sugars or starch, and biodiesel from transesterification of triglycerides. Evaluate with a life-cycle view: energy input, land use, water, and net greenhouse gas emissions. Second-generation fuels from waste cellulose avoid competition with food.
Common mistakes and connections: Carbon neutral is a simplification, since fertilizer, processing and land-use change add emissions. Ethanol has lower energy density than gasoline, about two thirds, so mileage falls. This topic links to fermentation, esterification and sustainability.
Visualization of Biofuels
Bioethanol, made by fermenting sugars, is a renewable fuel releasing about 1367 kJ/mol on combustion; its carbon was recently taken from the air. The interactive lesson shows this as a live animation or chart.
Worked example and use case
Brazil runs many of its cars on sugarcane ethanol, either pure or blended with gasoline.
Frequently asked questions about Biofuels
What is Biofuels?
Renewable fuels such as ethanol and biodiesel derived from biomass.
Is Biofuels a beginner, intermediate or advanced topic?
Biofuels is a intermediate topic in Thermodynamics & Energetics. It builds on the vocabulary of beginner topics in this area.
What should I learn before Biofuels?
Study these earlier topics in Thermodynamics & Energetics first: Energy Density, Fossil Fuels, Hydrogen as Fuel.
What comes after Biofuels?
The next topics in Thermodynamics & Energetics are Hess's Law Cycle Diagram and Enthalpy Level Diagram.
Can I practise Biofuels with quizzes?
Yes. The interactive lesson includes a self-check question on Biofuels, and the Thermodynamics & Energetics quiz draws on every topic in this area.
Where Biofuels fits in Thermodynamics & Energetics
Biofuels is topic 74 of 91 in Thermodynamics & Energetics.