Researchers from the National Institute for Environmental Studies and Potsdam Institute for Climate Impact Research, Ritsumeikan University and Kyoto University conducted a new collaboration research that found that while unlimited irrigation could increase the global BECCS potential via the increase in bioenergy production by 60-71%, sustainable constrained irrigation would only increase it by 5-6%. Nature Sustainability published the study on July 5.Bioenergy with carbon capture storage (BECCS), is the extraction of bioenergy from biomass and then the capture and storage of carbon in a geological reservoir. Because the biomass is created by photosynthesis, plants can absorb carbon dioxide from the atmosphere. It is therefore a zero emission technology. Large-scale deployment of BECCS is required to achieve the 1.5C or 2C climate goals. This was a conclusion that was supported in previous studies. This raised concerns about the difficulties associated with water and land resources for the production of bioenergy crops. Existing studies show that irrigation is necessary to produce sufficient bioenergy crops to meet the requirements of 1.5C climate goals. This would cause severe water stress, even more than climate change.This context shows that it is not clear where and how irrigation can increase the global BECCS potential. Sustainable water use remains a question. It is water use that secures water availability in the local and downstream areas for conventional water uses and environmental flow requirements. It also suppresses nonrenewable water resource withdrawal and prevents water stress. Zhipin Ai, lead author from Japan's National institute for environment studies, explains.Simulations were used to represent the spatially explicit bioenergy crop plantations as well as the water cycle within an internally consistent model framework. The researchers developed distinct irrigation methods (unlimited, sustainable, and no) for different land types to quantify the limitations of irrigation water resources. This was done to avoid adverse effects on biodiversity, food production, and desertification caused by large-scale land conversion.According to the study, the global BECCS potential under rainfed conditions was 0.82-99 Gt C per year-1. Under full irrigation, the BECCS potencil reached 1.32-3.42 Gt C per year (60% and 71% respectively) while under sustainable irrigation it was 0.88-2.09 Gt C per year (5% and 66%, respectively) The BECCS potential with sustainable irrigation is very close to the lower limit (1.6-4.1 GtC yr-1), which is the minimum amount of BECCS required in 2100 in accordance with the 1.5C and 2C climate goals as documented in the IPCC Special report on Global Warming of 1.5C.The researchers recommend that comprehensive assessments of BECCS potential, which consider both the potential benefits and the adverse effects, be done in order to simultaneously achieve multiple sustainable development goals, including climate, water, and land. "Also, given the low biophysically constrained BECCS potencial under sustainable water use and land use scenarios, it is necessary to critically reexamine the contribution of BECCS to the Paris Agreement goal." Vera Heck, co-author from the Potsdam Institute for Climate Impact Research, said this.###This study was funded by the Environment Research and Technology Development Fund, JPMEERF15S11418 and JPMEERF20211001, both part of the Environmental Restoration and Conservation Agency of Japan.
