Simulating second-generation herbaceous bioenergy crop yield using the global hydrological model H08 (v.bio1)

Zhipin Ai,Shinichiro Fujimori,Vera Heck,Naota Hanasaki,Tomoko Hasegawa

doi:10.5194/gmd-13-6077-2020

Abstract

Abstract. Large-scale deployment of bioenergy plantations would have adverse effects on water resources. There is an increasing need to ensure the appropriate inclusion of the bioenergy crops in global hydrological models. Here, through parameter calibration and algorithm improvement, we enhanced the global hydrological model H08 to simulate the bioenergy yield from two dedicated herbaceous bioenergy crops: Miscanthus and switchgrass. Site-specific evaluations showed that the enhanced model had the ability to simulate yield for both Miscanthus and switchgrass, with the calibrated yields being well within the ranges of the observed yield. Independent country-specific evaluations further confirmed the performance of the H08 (v.bio1). Using this improved model, we found that unconstrained irrigation more than doubled the yield under rainfed condition, but reduced the water use efficiency (WUE) by 32 % globally. With irrigation, the yield in dry climate zones can exceed the rainfed yields in tropical climate zones. Nevertheless, due to the low water consumption in tropical areas, the highest WUE was found in tropical climate zones, regardless of whether the crop was irrigated. Our enhanced model provides a new tool for the future assessment of bioenergy–water tradeoffs.

Highlights

Bioenergy with carbon capture and storage technology enables the production of energy without carbon emissions while sequestering carbon dioxide from the atmosphere, producing negative emissions
We enhanced the ability of the H08 global hydrological model to simulate the yield of the dedicated second-generation herbaceous bioenergy crops
The enhanced model could be a good tool for the future assessments of the bioenergy–water tradeoffs

Summary

Introduction

Bioenergy with carbon capture and storage technology enables the production of energy without carbon emissions while sequestering carbon dioxide from the atmosphere, producing negative emissions. Second-generation bioenergy crops, such as Miscanthus and switchgrass, are generally regarded as a dedicated bioenergy source due to their high yield potential and lack of direct competition with food production (Beringer et al, 2011; Yamagata et al, 2018; Wu et al, 2019). This is because Miscanthus and switchgrass are rhizomatous perennial C4 grasses, which have a high photosynthesis efficiency (Trybula et al, 2015). These two crops have been included in a series of models including Lund–Potsdam–Jena managed

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