我国燃煤电厂每年排放CO₂超过57亿 t，为保障双碳目标如期实现，必须大幅降低燃煤电厂的CO₂排放。微藻固碳通过高效的光合作用吸收CO₂转化为生物质，是极具潜力的燃煤电厂减碳技术，但目前微藻固碳性能严重受限于反应器内光传输。导光管可灵活调节反应器内光分布，而光纤可集中传输光线且光损耗低，因此提出光纤/导光管微藻光生物反应器，扩大藻液受光面积，增加藻细胞色素的光捕集，促进微藻光合固碳。利用光学仿真软件对光纤/导光管内传输的光线进行追踪，获得了光纤/导光管管壁的光强分布。在不同反应器、输入光能条件下进行微藻培养实验，获得了微藻生物量、固碳速率与叶绿素含量的变化趋势，分析了内置光纤/导光管对微藻固碳的影响规律。结果表明：平面末端的光纤射出光的光强在导光管侧30～140 mm内迅速下降，导光管发光范围集中。在导光管底部添加锥形反光件反射抵达管底的透射光、并设计阶梯型光纤使输入光由不同阶梯分级发出，可使微藻光生物反应器内光分布更加均匀，反应器内部远离光源区域的藻细胞可以有效接受光能进行光合固碳。当光能输入为3.3 W/L时，含两级阶梯结构光纤和锥形反光件的导光管管侧表面最低光强为47 μmol/（m²·s），平均光强达64 μmol/（m²·s），较无光纤仅顶部给光的导光管侧面平均光强提高了2.6倍。微藻在插入阶梯型光纤的光生物反应器（SF-PBR）培养7 d后生物量达到1.9 g/L，比在插入平面端光纤的光生物反应器（FF-PBR）中培养的生物量高46.2%，比仅顶部受光的光生物反应器（LG-PBR）中培养的生物量高111.1%。当提升光源输入至5.0 W/L，微藻培养7 d后的生物量高达2.8 g/L，培养期间保持高固碳速率（608.3 mg/（L·d）），比对照组LG-PBR的固碳速率提高1.9倍。

China’s coal-fired power plants emit over 5.7 billion tons of CO₂ annually. To realize the dual carbon goals in time, it is necessary to reduce the carbon emissions of coal-fired power plants. Microalgae carbon fixation can efficiently absorb CO₂ through photosynthesis and convert it into biomass, which is a highly promising technology for carbon reduction in coal-fired power plants. Light guide tubes can flexibly change the light distribution in a photobioreactor, while optical fibers can transmit light centrally with low light loss. Therefore, a microalgae photobioreactor with an optical fiber/light guide tube is proposed to expand the light-receiving area of the microalgae suspension, increase the light-harvesting of microalgal cells, and promote carbon fixation via microalgae photosynthesis. The optical simulation software was used to trace the propagation of light in the optical fiber/light guide tube, and the light intensity distribution of the tube wall was obtained. Microalgae cultivation experiments were conducted in various photobioreactors and under different input light energy conditions. The change trends of biomass yield, carbon sequestration rate, and chlorophyll content were obtained, and the impact of built-in optical fiber /light guide tubes on carbon fixation via microalgae was investigated. Results indicated that the light intensity emitted from the optical fiber terminal decreased precipitously from 30 mm to 140 mm along the side of the light guide tube. Additionally, the tube exhibited a concentrated light-emitting range. Adding a conical reflector to reflect the transmitted light at the tube bottom and designing a stepped optical fiber to emit input light from different steps can optimize the light-emitting effect of the light guide tube and make the light distribution in the microalgae photobioreactor more uniform, so that the microalgal cells far away from the light source area can receive the light energy to photosynthesize and fix carbon. At a light input of 3.3 W/L, the minimum light intensity on the side surface of the light guide comprising a two-stage stepped optical fiber and conical reflector was 47 μmol/(m²·s). The average light intensity was 64 μmol/(m²·s), representing a 2.6-fold increase compared to the light guide tube lacking both the optical fiber and any enhancements beyond its top section. After seven days of cultivation, the microalgae concentration in the stepped fiber photobioreactor (SF-PBR) could reach 1.9 g/L, which was 46.2% higher than that of the photobioreactor inserted with flat-end fiber optic light guide (FF-PBR) and 111.1% higher than that of the photobioreactor with only top-fed light (LG-PBR). When the light input was escalated to 5.0 W/L, a high microalgae concentration of 2.8 g/L was achieved at 7 d. Meanwhile, the average carbon sequestration rate of 608.3 mg/(L·d) was obtained, exhibiting 1.9-fold augmentation compared to the control LG-PBR.