Bioethanol: Impact on the biosphere

Food versus fuel: the farming footprint behind ethanol

What this tab covers Effects on human, animal, plant, fungal and microbial life and on whole ecosystems: in the short term (construction and early years), medium term (operating life) and long term (decommissioning and legacy).

Ethanol's impacts come mainly from farming its feedstock: land use and land-use change, fertiliser, water and the working conditions of harvest labour.

Indirect land-use change, corn ethanol (jet route, ICAO) 18.3-34.9 g CO2eq/MJ⁵ Indirect land-use change, sugarcane ethanol (jet route, ICAO) 8.5-11.9 g CO2eq/MJ⁵ Fossil fuel comparator used by the EU 94 g CO2eq/MJ⁴

Effects over time

Life affected	Short term	Medium term	Long term
Humans¹¹²⁸	Manual cane cutting is physically demanding, with long hours, heat and pesticide exposure, often paid by volume cut and without formal contracts.	Mechanisation is reducing manual cutting; in Brazil it was projected to remove 86,000-230,000 migrant jobs. Biofuels and other industrial uses are projected to take roughly a quarter of world cereal use by 2035.	Little evidence of lasting effect beyond the farming phase.
Animals¹	Little evidence of effect in the sources reviewed.	Little evidence of effect in the sources reviewed; distillers grains are a significant livestock feed.	Little evidence of effect in the sources reviewed.
Plants⁸⁵	Natural vegetation may be cleared where new cropland is opened.	Global maize area is projected to expand by about 4% to meet food, feed and fuel demand.	Indirect land-use change: ICAO adds 8.5-11.9 g CO2eq/MJ for sugarcane and 18.3-34.9 g CO2eq/MJ for corn ethanol used for jet fuel.
Fungi and soil life¹	Little evidence of effect in the sources reviewed.	Heavy nitrogen application (about 136.5 lb per acre of corn) affects soil chemistry; impacts on soil microbes are not quantified in the sources reviewed.	Little evidence of effect in the sources reviewed.
Ecosystems⁹⁴	Water drawn for crops and mills.	Excluding land-use change, EU defaults give savings of 48-70% versus petrol for crop ethanol and 83-85% for straw ethanol.	Net climate benefit depends on whether forests or grasslands are converted to grow fuel crops.

How the effects are reduced

Using residues such as straw and bagasse rather than food crops raises savings to 83-85% under EU default values and avoids new cropland. Sugarcane mills that burn bagasse in efficient CHP cut fossil energy use; corn plants that sell wet rather than dried grains save drying energy, lifting the energy ratio from 2.1 towards 4.0. Mechanised harvesting removes the hardest manual work, though it also removes jobs, so labour transition matters. Sustainability rules under the EU directive and ICAO scheme are designed to restrict feedstocks grown on high-carbon or recently cleared land.

Sources

2015 Energy Balance for the Corn-Ethanol Industry (published February 2016) US Department of Agriculture, 2016
The Sustainability of Brazilian Sugarcane Bioethanol: A Literature Review (Barber, Pellow and de Aragao Pereira, for EECA) AgriLINK NZ / Bioenergy Association of New Zealand, 2008
Directive (EU) 2018/2001 (Renewable Energy Directive II), Annex V: typical and default greenhouse gas savings for biofuels (Parts A and B); fossil comparator 94 g CO2eq/MJ. Default values not changed by amending Directive (EU) 2023/2413 (RED III); a Commission revision was in draft in 2026 European Union (EUR-Lex), 2018
CORSIA Default Life Cycle Emissions Values for CORSIA Eligible Fuels (ICAO document 06) International Civil Aviation Organization, 2025
Food crops to remain backbone of global biofuel production through 2035 (summary of OECD-FAO Agricultural Outlook 2026-2035; feedstock shares are 2035 projections) Down To Earth, 2026
The water footprint of bioenergy and other primary energy carriers (Gerbens-Leenes, Hoekstra and van der Meer, Value of Water Research Report 29) UNESCO-IHE / University of Twente, 2008
Renewable Energy and Jobs: Annual Review 2025 (Table 1, 2024 employment) IRENA and International Labour Organization, 2025