Environmental and economic impacts of processing rice straw with water for energy and coproducts

Abstract

Incorporating supplementary cementitious materials (SCM) such as rice straw ash (RSA) as cement replacement in concrete is a key path toward mitigating the contributions of cement to global climate change. A cost-benefit study and an environmental life cycle assessment (LCA) were performed to compute the impacts of water soaking, drying, and reverse osmosis (RO) of the leachate to factor in the use of rice straw as feedstock at biomass energy plants, RSA for concrete, and the RO-treated leachate as fertilizer and water for farms. The cost-benefit analysis showed that the sale of electrical energy from biomass, RSA, and fertilizer required further optimization of the processes to become profitable for the involved parties. The LCA showed a global warming avoidance equivalent to net -15kgCO_2-eq per tonne of rice straw that could be achieved by substituting fossil fuel energy resources and cement avoidance in concrete.