Development Of An Efficient BECCS System Based On Bicarbonate

As the most important greenhouse gas,excessive CO₂ emissions have caused global climate change and triggered a series of environmental problems.However,from another perspective,CO₂ can also be a rich inorganic carbon resource,and it is of great practical significance to carry out effective recycling and resource utilization.Among many CO₂ capture technologies,chemical absorption is the most common application,but it has a bottleneck of high energy consumption for regeneration.Compared with the traditional chemical absorption method,the advantage of biological carbon sequestration is green and no the risk of secondary pollution.For example,by using photosynthesis,microalgae can synthesize CO₂ as the carbon source for growth,and synthesize other high-value additional products such as oils,polysaccharides,and proteins.However,in the process of microalgae cultivation,nutrient salt cost and low carbon sequestration efficiency are obstacles to its wide range of applications.In order to solve the problem of high energy consumption of chemical absorption and low carbon sequestration efficiency of microalgae,a bioenergy coupled with carbon dioxide capture and storage system based on bicarbonate was developed.Combining the advantages of chemical absorption and microalgae carbon fixation,high efficiency and low cost CO₂ capture and resource utilization are realized.In this paper,two strains of Spirulina platensis were studied,and the effects of CO₂ on chemical growth of different types and concentrations of bicarbonate on the growth of Spirulina were investigated.The experimental results showed that the mutagenized Spirulina platensis was most suitable for survival in the BECCS system with bicarbonate（0.3 mol/L Na HCO₃）as the link.The highest biomass dry weight was2.24 g/L,the maximum carbon fixation was 230.36 mg/L/d,and the carbon utilization efficiency was 26.71%.In order to further improve the carbon utilization efficiency,the subsequent work introduced some NH₄HCO₃ to replace Na NO₃ in the traditional medium.The experimental results show that when the ratio of NH₄HCO₃ to Na NO₃ was 1:4,the carbon utilization efficiency was increased to 40.45%.The inorganic carbon remaining in the solution was again used as an absorbent to trap CO₂,and the saturated bicarbonate was absorbed for the culture of spirulina.The specific growth rate of spirulina did not change significantly during the three cycles.It can be shown that the BECCS system with bicarbonate as the link has continuous stability and has the potential and application prospects to replace the traditional single chemical absorption or microalgae carbon sequestration technology.