What crop rotation will provide optimal first-generation ethanol production in Ireland, from technical and economic perspectives?
Civil and Environmental Engineering
This paper describes a technical and economic analysis of the potential ethanol production from wheat, barley and sugar beet in Ireland for three different combinations of the crops. Scenarios are investigated which include for three crop rotations: (1) wheat, barley and sugar beet; (2) wheat, wheat and sugar beet; and (3) wheat only.
Ethanol production facilities typically employ either starch or sugar feedstocks which may not be optimised if both starch and sugar feedstocks are used. Thus, the scenarios which include sugar beet require two separate facilities.
The study shows that technical optimisation gives a different rotation to an economic optimisation. It was found that the starch feedstocks (wheat and barley) produce more ethanol per tonne of feedstock than the sugar feedstock (sugar beet). However, on a land area basis, sugar beet produces significantly more ethanol, and hence more energy, than either wheat or barley. In order to meet the EU Biofuels Directive, it is crucial to maximise the energy return per unit of land. Thus, optimisation on the basis of minimisation of land take gives a rotation of wheat, wheat and sugar beet, as this scenario produces the greatest quantity of energy per hectare, whereas optimisation on an economic basis suggests wheat alone with the lowest production cost of €0.6/l.
Power, N., Murphy, J.D. & McKeogh, E., 2008. What crop rotation will provide optimal first-generation ethanol production in Ireland, from technical and economic perspectives? Renewable Energy, 33(7), pp.1444–1454. Available at: http://dx.doi.org/10.1016/j.renene.2007.09.019.