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Licentiate thesis, 2013

Food or fuel?

Johansson, Sheshti

Abstract

There are great expectations on agriculture to provide both food and fuels in the future. Previous attempts to estimate the global bioenergy potential have produced varying results, indicating major uncertainty. This thesis investigated the global theoretical 'potential', or limit, for biofuels based on current agricultural systems. The results showed that use of edible crops for biofuels in the current global food system would lead to a global deficit of food. Producing biofuels from residues also proved to have uncertain 'potential' and could not exceed 8 x 103 TWh. Despite the global limitations of biofuel production in the current food system, agriculture is essentially the only truly indispensable sector and may need to be independent of fossil fuels in the future due to depletion of these resources. Therefore a small-scale, low-input food system was studied to examine the effects of fuel self-sufficiency in farm work on food production and nutrient fluxes. It was found that using wheat or potatoes for ethanol production lowered food production by 23% and 18%, respectively, compared with the reference scenario of conventional diesel. The least impact on food production (94% of the reference scenario) was obtained by combining a draught horse and cold-pressed rapeseed oil produced on-farm. By producing the fuel on-farm, a larger degree of nutrient recycling could be obtained. The draught horse-rapeseed oil scenario had only a small phosphorus (P) deficit, but the potassium (K) deficit was significant in all scenarios except when potatoes were used for ethanol production. Potassium deficiency is not a problem on soils formed on sedimentary clay in Sweden, but for such alternative fuel system to be viable in other regions, some solution for recycling K will be increasingly required. Nitrogen (N) level was maintained in all scenarios due to the inclusion of N-fixing leys. The P level can be maintained in arable fields if bones are recycled. However, nutrients, especially K, are also moved from meadow to cropland.

Keywords

Biofuels; food production; food and biofuel production; global biofuel potential; small-scale agriculture; draught horse power; self-sufficiency; small-scale biofuel production

Published in

Rapport (Institutionen för energi och teknik, SLU)
2013, number: 064
ISBN: 978-91-576-9170-5, eISBN: 978-91-576-9171-2
Publisher: Department of Energy and Technology, Swedish University of Agricultural Sciences

Authors' information

Johansson, Sheshti
Swedish University of Agricultural Sciences, Department of Energy and Technology

UKÄ Subject classification

Renewable Bioenergy Research
Energy Systems
Agricultural Science

URI (permanent link to this page)

https://res.slu.se/id/publ/51917