The potential of triticale as a low input cereal for bioethanol production

Abstract

The aim of this work was to quantify the performance of modern triticale varieties grown under UK conditions, to assess their value for the bioethanol market, and to evaluate any potential greenhouse gas savings made in comparison with production of winter wheat.

Using twenty samples of winter triticale from UK Descriptive List trials harvested in 2007 (representing thirteen different varieties), alcohol yields  (AY; L ethanol/t grain) were quantified as well as starch and protein contents, grain size and hardness.  AY was determined based on a modified method for assessment of distilling wheats for the Recommended List, and compared to AY of two Istabraq (wheat) samples of similar protein contents. 

Triticale was shown to be a feedstock with high potential for bioethanol production, with a soft grain, giving alcohol yields comparable with Istabraq at equivalent grain protein contents (average 436 L/t DM at 11.5% grain protein). Some triticale varieties (Fidelio, SW Fargo, Trimester, Ego and Grenado in particular) showed better than expected AY based on their protein contents, thus demonstrating their potential as feedstocks for bioethanol production. The ratio of conversion of starch to alcohol (6.44 L/10 kg starch) was relatively high compared to values seen previously for wheat. Further work is needed to understand variation in starch and fermentable sugars in modern triticale varieties, and in different agronomic situations. Residue viscosity of the triticale samples was higher than that of wheat, but alcohol yields should now be assessed using industrial enzymes representative of those which would be used in a modern bioethanol plant and which would reduce viscosity. 

In all scenarios studied using the HGCA Biofuels calculator, the net benefits in terms of reducing GHG emissions associated with bioethanol production, were greater for triticale than for wheat, principally due the lower N requirement of triticale. However, there is considerable uncertainty regarding the average grain protein content of triticale when fertilized at the economic optimum. There is also no data on the relative yields of wheat and triticale grown with their respective N optima, in both high and low yield potential situations. The major advantage of triticale may be in 2nd/3rd cereal positions in the rotation when the yield of wheat tends to be reduced by take-all. More work needs to be carried out to compare these two species side by side in replicated trials.