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. 2016 Mar 3;6:22521.
doi: 10.1038/srep22521.

The Water-Land-Food Nexus of First-Generation Biofuels

Free PMC article

The Water-Land-Food Nexus of First-Generation Biofuels

Maria Cristina Rulli et al. Sci Rep. .
Free PMC article


Recent energy security strategies, investment opportunities and energy policies have led to an escalation in biofuel consumption at the expenses of food crops and pastureland. To evaluate the important impacts of biofuels on food security, the food-energy nexus needs to be investigated in the context of its linkages with the overall human appropriation of land and water resources. Here we provide a global assessment of biofuel crop production, reconstruct global patterns of biofuel crop/oil trade and determine the associated displacement of water and land use. We find that bioethanol is mostly produced with domestic crops while 36% of biodiesel consumption relies on international trade, mainly from Southeast Asia. Altogether, biofuels rely on about 2-3% of the global water and land used for agriculture, which could feed about 30% of the malnourished population. We evaluate the food-energy tradeoff and the impact an increased reliance on biofuel would have on the number of people the planet can feed.


Figure 1
Figure 1
(A) Bioethanol is obtained from carbohydrates of sugar or starchy crops via alcoholic fermentation, a biological process in which bacteria convert sugars such as glucose, fructose and sucrose into ethanol. (B) Biodiesel is a vegetable oil or animal fat based fuel; it consists of long-chain alkyl (methyl, ethyl, or propyl) esters. It is typically made by chemically reacting lipids with an alcohol, which leads to the production of fatty acid esters. This chemical reaction is known as trans-esterification.
Figure 2
Figure 2
For the top 14 bioethanol consumers we show the resources used for bioethanol production (A), including both domestic production for in country use and imports) in terms of: (B) Land; (C) Water; (D) Food equivalent, i.e., people who could be fed with crops used for bioethanol (based on country-specific rates of calorie consumption (Table S2)). Most of the global water consumption for bioethanol production (>50%) is contributed by maize in the USA and sugar cane in Brazil (C). Because of their reliance on these two different feedstocks, the water and land used in Brazil are substantially lower than in the USA (Table 2). The water consumed globally for bioethanol is primarily from rainwater (or “green”) (76%), though considerable amounts of (“grey”) water for pollutant dilution (14%) and irrigation (“blue”) water (10%) are also used (Table 3).
Figure 3
Figure 3
Biodiesel consumption (A). Land (B) and Water (C) used for biodiesel production, and (D) Number of People who could be fed with the crops used for biodiesel production in the top 14 biodiesel consumers in the world (based on country-specific rates of calorie consumption (Table S2)).
Figure 4
Figure 4. World map of energy flows related to bioethanol and biodiesel trade.
The round symbol refers to multiple countries in the area (1PJ = 1015J; 1 Ml = 106 litres). [Figure generated with ®Microsoft PowerPoint. The base map is available from OpenStreetMap ( and is licensed under the Attribution-Share-Alike 2.0 license. The license terms can be found on the following link:].

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