Potential agronomic options for energy‐efficient sugar beet‐based bioethanol production in northern Japan

Abstract

Sugar beet (Beta vulgaris L. subsp. vulgaris) is deemed to be one of the most promising bioethanol feedstock crops in northern Japan. To establish viable sugar beet-based bioethanol production systems, energy-efficient protocols in sugar beet cultivation are being intensively sought. On this basis, the effects of alternative agronomic practices for sugar beet production on total energy inputs (from fuels and agricultural materials during cultivation and transportation) and ethanol yields (estimated from sugar yields) were assessed in terms of (i) direct drilling, (ii) reduced tillage (no moldboard plowing), (iii) no-fungicide application, (iv) using a high-yielding beet genotype, (v) delayed harvesting and (vi) root 1 crown harvesting. Compared with the conventional sugar beet production system used in the Tokachi region of Hokkaido, northern Japan, which makes use of transplants, direct drilling and no-fungicide application contributed to reduced energy inputs from raising seedlings and fungicides, respectively, but sugar (or ethanol) yields were also reduced by these practices, to a greater equivalent extent than the reductions in energy inputs. Consequently, direct drilling (6.84 MJ L À1 ) and nofungicide application (7.78 MJ L À1 ) worsened the energy efficiency (total energy inputs to produce 1 L of ethanol), compared with conventional sugar beet production practices (5.82 MJ L À1). Sugar yields under conventional plow-based tillage and reduced tillage practices were similar, but total energy inputs were reduced as a result of reduced fuel consumption from not plowing. Hence, reduced tillage showed improved energy efficiency (5.36 MJ L À1 ). The energy efficiency was also improved by using a highyielding genotype (5.23 MJ L À1 ) and root 1 crown harvesting (5.21 MJ L À1). For these practices, no major changes in total energy inputs were noted, but sugar yields were consistently increased. Neither total energy inputs nor ethanol yields were affected by extending the vegetative growing period by delaying harvesting.

Assessing energy efficiencies and greenhouse gas emissions under bioethanol-oriented paddy rice production in northern Japan

“…3). Under the conventional rice production system in Hokkaido, the energy efficiency during cultivation and transportation of feedstock was 12.8 MJ L À1 , which was 2.2-fold greater than that under a sugar beet-based bioethanol production system (5.82 MJ L À1 ) in Hokkaido (Koga et al, 2009). The most energetically efficient practice was a combination of using the high-yielding variety and straw return (21% reduction over the conventional practice).…”

Sugar Beet as an Energy Crop

“…In the Americas, Brazil (from sugar cane) and the U.S. (from maize) are the major ethanol producers and users. Globally, there is a strong interest in Asia in the use of sugar beet as one of a number of potential bioethanol feedstocks-Turkey (Içöz et al 2009), Japan (Hatano et al 2009;Koga et al 2009;Koga 2008) China (Tian et al 2009), and India (Srivastava et al 2008). Because storing the harvested roots is a large impediment to using sugar beet as a bioethanol feedstock, climates where sugar beet can be cultivated both as spring or fall sown crops, will be the most attractive areas for biofuel production because the crop can be harvested daily most of the year.…”