Study finds that biofuel crops grown on marginal lands could produce up to half of world’s current liquid fuel consumption without impacting crops
|Maps of land available for bioenergy production under one of the scenario 4 in US, Europe, China, India, South America, and Africa. Credit: ACS, Cai et al. Click to enlarge.|
Using detailed land analysis, University of Illinois researchers have found that biofuel crops cultivated on available land could produce between 26-55% of the world’s current fuel consumption without affecting the use of land with regular productivity for conventional crops and without affecting the current pasture land.
Published in the ACS journal Environmental Science and Technology, the study led by civil and environmental engineering professor Ximing Cai identified land around the globe available to produce grass crops for biofuels, with minimal impact on agriculture or the environment.
Under any of the projections, Africa has more than one third, and Africa and South America have more than half of the total land available for biofuel production. Thus, the locations of biofuel production potential and demand are not consistent, given that larger fuel demands exist in the US, Europe, China, and India. The transportation of this fuel between continents will cause additional energy consumption.—Cai et al.
Many studies on biofuel crop viability focus on biomass yield, or how productive a crop can be regionally. There has been relatively little research on land availability, one of the key constraints of biofuel development. Of special concern is whether the world could even produce enough biofuel to meet demand without compromising food production.
The questions we’re trying to address are, what kind of land could be used for biofuel crops? If we have land, where is it, and what is the current land cover?
Cai’s team assessed land availability from a physical perspective—focusing on soil properties, soil quality, land slope, and regional climate. The researchers collected data on soil, topography, climate and current land use from some of the best data sources available, including remote sensing maps.
The critical concept of the Illinois study was that only marginal land would be considered for biofuel crops. Marginal land refers to land with low inherent productivity, that has been abandoned or degraded, or is of low quality for agricultural uses. In focusing on marginal land, the researchers rule out current crop land, pasture land, and forests. They also assume that any biofuel crops would be watered by rainfall and not irrigation, so no water would have to be diverted from agricultural land.
Using fuzzy logic modeling, the researchers considered multiple scenarios for land availability. First, they considered only idle land and vegetation land with marginal productivity; for the second scenario, they added degraded or low-quality cropland. For the second scenario, they estimated 702 million hectares of land available for second-generation biofuel crops, such as switchgrass or miscanthus.
The researchers then included marginal grassland. A class of biofuel crops called low-impact high-diversity (LIHD) perennial grasses could produce bioenergy while maintaining grassland. While they have a lower ethanol yield than grasses such as miscanthus or switchgrass, LIHD grasses have minimal environmental impact and are similar to grassland’s natural land cover.
Adding LIHD crops grown on marginal grassland to the marginal cropland estimate from earlier scenarios nearly doubled the estimated land area to 1,107 million hectares globally, even after subtracting possible pasture land —an area that would produce 26 to 56% of the world’s current liquid fuel consumption. Next, the team plans to study the possible effect of climate change on land use and availability.
It should be noted that not all the estimated land, particularly abandoned or degraded cropland, can be used for bioenergy production. Furthermore, trade-offs may exist between the present environmental and ecological value of MAL and the potential value for biofuel production...
The final land availability will be affected by not only the physical feasibility factors described above but also global energy and food markets, technological innovations, social and institutional adaptations and accommodations, engineering infrastructural support, and resources availability (e.g., water for refinery industry). Nevertheless, the MAL land maps generated in this study can be used as a base to consider these conditions for further exploration of land available for biofuel production; the estimates can also be integrated with research efforts in biology and agronomy to help identify productive plant species, genetics, and create sustainable crop techniques.
The challenges for the world are to identify the most highly productive plant species that can be grown on the various types of marginal or abandoned lands and to develop innovative land use systems specifically designed for energy crops that have high energy productivity and meanwhile support species diversity and community development.—Cai et al.
The Energy Biosciences Institute at U. of I. and the National Science Foundation supported the study.
Ximing Cai, Xiao Zhang, Dingbao Wang (2011) Land Availability for Biofuel Production, Environmental Science & Technology 45 (1), 334-339 doi: 10.1021/es103338e