Crop forage such as rice straw is susceptible to rot and deterioration. Hence utilizing them in low-carbon and decarbonization industries that assume long-term carbon storage was challenging. The National Agriculture and Food Research Organization (NARO) has developed a new technology, the GrAAS process, which makes it easier to unravel the fibers of forage by treating them with acid at room temperature. A detailed analysis of this phenomenon was conducted in collaboration with Saitama University and the University of Tokyo. This process allows us to easily use forage as fibers and structural materials, and also the saccharification properties of fibers are improved, making it possible to convert them into biofuels, etc. This technology is expected to create a low-carbon industry from agriculture.
Overview
With the intensification of climate change, there is a need to accelerate measures such as low-carbon and decarbonization efforts. DAC (Direct Air Capture) technology, which directly separates and captures dilute CO2 in the air, is gaining attention as one of the countermeasures. Agriculture and forestry are regarded as industries that can assist DAC by capturing atmospheric CO2 through photosynthesis and converting it into biomass. However, since crop forage such as rice straw rots and deteriorates in a short period of time, its contribution to low carbon emissions and decarbonization is limited when compared to wood biomass, which stores carbon through long-term use, such as building materials and paper.
NARO discovered that forage such as rice straw can be easily used as fiber or saccharification raw material by treating it with room-temperature acid using a special method and named as GrAAS process. (Grass Upcycling by Activated Acid into the Sugar Pool) and conducted a detailed analysis of this phenomenon in collaboration with Saitama University and Graduate School of Agricultural and Life Sciences, The University of Tokyo.
The GrAAS process uses highly active hydrochloric acid to grind modified forage powder under liquid or gas phase conditions, resulting in a highly dispersible suspension in water. Also, when this suspension is enzymatically saccharified, sugar can be recovered at a higher recovery rate than the control sample suspension.
By using the newly developed GrAAS process to convert forage, which has so far been underutilized, into fibers, the production of paper, board, lignocellulose nanofibers, etc. can be made more efficiently, and it can be used as a carbon pool suitable for long-term use. Also, it will contribute to low carbon emissions by enzymatically saccharifying this fiber to recover sugar and converting it into biofuels, bioplastic raw materials, etc., Furthermore, the new material derived from forage, which has the property of "recovering sugar after long-term use" can be stored for a long time as "storage sugar" and it can be converted into fuel, feed or food when needed.
In the future, we will demonstrate small-scale manufacturing technology by expanding the scale of testing of the GrAAS process, providing prototype samples, evaluating material characteristics, etc., and aim for the early social implementation of the technology.
Publication
Tokuyasu K.,Yamagishi K.,Kotake T.,Kimura S.,Ike M.:Hydrogen chloride treatment of rice straw for upcycling into nanofibrous products for sugar pool. Bioresource Technology Reports, doi.org/10.1016/j.biteb.2023.101717
