CAS-CLIMATE: DIRECT METHANE CAPTURE IN AIR BY AEROBIC METHANOTROPHS

在100年的时间尺度上，甲烷的变暖影响是二氧化碳的34倍，在20年的时间尺度上，甲烷的影响是二氧化碳的86倍，甲烷在大气中的半衰期相对较短(约10年)，为近期缓解气候变化提供了机会。该项目的目标是创造一种技术，通过大规模消除空气中的甲烷，为减缓全球变暖奠定基础。由于甲烷浓度低(1.89ppm)，从大气中去除甲烷是一项挑战。该项目的重点是创造技术，利用甲烷消耗细菌(甲烷营养菌)，在排放导致空气中局部浓度较高的地点，如许多垃圾填埋场、污水处理厂、煤矿、油气井、饲养场和水电站大坝，从空气中去除甲烷。许多甲烷氧化菌可以稳定地维持在500ppm甲烷，这使得这个浓度可能成为反应器部署的目标。美国有数万个这样的地点，预计其上方空气中的甲烷含量为500ppm或更多，这为实现大规模的大气甲烷捕获提供了机会。尽管现有的生物过滤技术可以去除废气中的甲烷，但它针对浓度更高的甲烷进行了优化，在500ppm的甲烷浓度下是不可行的。该项目旨在形成一个实验室原型，用于消耗空气中甲烷含量大于或等于500ppm的场所的甲烷，目标是使目前的处理能力(甲烷消耗量/立方米处理量/年)增加10倍。该项目将从利德斯特罗姆实验室发现的甲烷氧化菌开始，它们的甲烷消耗率为500ppm，是文献中任何甲烷消耗率的2-4倍，并开发改进的菌株和优化的生长条件，包括联合体。然后，该团队将使用优化的微生物群落来模拟、测试和优化甲烷消耗的改良生物滤池配置。在实验工作的同时，该团队将开发一个集成的建模框架，将过程模拟与影响评估结合起来，以评估几种潜在操作场景下的生物反应器系统。然后，该小组将进行相关的技术-经济和环境生命周期评估研究，以说明生物反应器系统广泛应用的经济可行性和环境效益的潜力，并指导进一步的研究和开发工作。实验和建模团队将在迭代设计过程中密切合作，以构建最终框架并获得可靠的可行性评估。长期目标是将这些生物反应器视为垃圾填埋场、污水处理厂、饲养场、水电站大坝、煤矿和其他地方的标准设备。这种甲烷捕获将对未来的气候产生强大的影响，特别是当与减少甲烷排放的平行努力相结合时。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Methane has a warming impact 34 times greater than CO2 on a 100-year timescale, and 86 times greater on a 20-year timescale, and its relatively short half-life in the atmosphere (~10 years) provides the opportunity for near-term climate mitigation. This project targets creation of a technology that would set the stage to slow global warming by removing methane from air at significant scale. Removing methane from the atmosphere is challenging due to the low concentration (1.89 ppm). This project focuses on creation of technology to remove methane from the air over sites where emissions result in locally higher concentrations in the air, such as many landfills, sewage treatment plants, coal mines, oil and gas wells, feedlots, and hydroelectric dams, using methane-consuming bacteria (methanotrophs). Many methanotrophs can be stably maintained at 500 ppm methane, making this concentration a possible target for reactor deployment. Tens of thousands of such sites in the United States are projected to contain 500 ppm or more methane in the overlying air, providing the opportunity to achieve atmospheric methane capture at scale. Although biofilter technology exists to remove methane from gaseous waste streams, it is optimized for more concentrated methane and is not practicable at 500 ppm methane. This project aims to result in a laboratory prototype for consuming methane from sites with 500 ppm or greater in the air, with a goal of a 10-fold increase over current capacity (methane consumed/m3 treatment volume/year).The project will start with methanotrophs identified in the Lidstrom lab that have 2- to 4-fold higher rates of methane consumption at 500 ppm than any in the literature, and develop improved strains and optimized growth conditions including consortia. The team will then model, test, and optimize for methane consumption a modified biofilter configuration using optimized microbial communities. Concurrently with experimental work, the team will develop an integrated modeling framework, coupling process simulation with impact assessment, to assess the bioreactor systems under several potential operating scenarios. The team will then conduct linked techno-economic and environmental life cycle assessment studies to illustrate the potential for economic feasibility and environmental benefit for widespread application of the bioreactor systems and guide further research and development work. The experimental and modeling teams will work closely and collaboratively, in an iterative design process to build the final framework and obtain a robust assessment of feasibility. The long term goal is to see these bioreactors as standard equipment at landfills, sewage treatment plants, feedlots, hydroelectric dams, coal mines, and elsewhere. This methane capture would have a powerful impact on the climate future, especially when coupled to parallel efforts to reduce methane emissions.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.