New methodologies for removal of methane from the atmosphere

该项目的目标是开发从环境空气中去除甲烷的低成本方法。许多甲烷来源，如牛和其他农业活动的排放，以及天然气工业的低等级排放，都不容易减少。结果，大量高甲烷含量的空气持续存在于污染源周围。这项概念验证研究将改进定位这种高甲烷空气体积的方法，并设计和测试简单廉价的甲烷去除方法，如温室土壤甲烷化，以及天然气装置周围的甲烷催化去除，以开发新的方法来减少其他难以处理的来源的甲烷排放。甲烷是一种强有力的全球变暖物质，是第二大人为温室气体。目前正在迅速上升的甲烷是由自然和人为来源排放的，其中约五分之三是由人类活动造成的。这些人为排放包括农业和废物（约占全球总排放量的三分之一），如牛的呼吸和稻田，垃圾填埋场和污水系统，以及化石燃料来源，如气体泄漏和煤矿通风。许多这样的来源广泛传播（例如牛的呼吸），因此被认为是难以减少的。同样，虽然较大的天然气和煤矿泄漏可以识别和停止，但较小的弥散性泄漏更难消除。因此，开发从环境空气中去除甲烷的低成本方法是减少全球甲烷负担的一个非常重要的先决条件。但是这种高甲烷气体的扩散排放并不容易被减少泄漏的努力所控制。这项提议的目的是设计和证明从空气中提取甲烷的低成本方法，这种方法可以很容易地应用于大量甲烷排放的环境。目的不是去除所有的甲烷，而是减少“习惯性”存在的高甲烷空气的混合比例。第一部分的工作重点是改进检测环境中高甲烷空气的方法。这项工作将使用移动车载高精度腔式分析仪，结合抓取采样进行高精度同位素分析，以确定来源（例如，使用c同位素区分气体泄漏与附近垃圾填埋气体排放）。该研究将开发在典型地点量化高甲烷空气体积的方法，从而评估在环境设置中去除的目标流量。在牛棚、饲料场和开放式牛奶棚，该项目将设计和测试甲烷减排，方法是在源头旁边的活跃温室中使用土壤甲烷化。富含甲烷的空气将在靠近污染源的地方（例如从开放式挤奶棚里牛的嘴和鼻子中）抽取，并将其泵入附近温室的基质土壤/生长介质中。在这里，甲烷营养细菌会将甲烷氧化成二氧化碳，然后被温室里的植物吸收。实验工作将测试该方法的可行性（例如能源成本）并优化条件（温度、湿度、气流等）。在工业环境中，如气体压缩机棚，或在封闭空间的大型废物系统附近，将测试使用MnO和CuO进行廉价化学催化去除。这些系统将基于甲烷实验室中使用的可靠、低成本的零空气发生器。目的不是去除所有的甲烷，而是优化经济的部分去除流量、最佳温度和湿度条件、再生催化剂的频率等。工作的最后一部分将是综合研究，以评估减少甲烷的可行性。一项有效的减排政策，无论是由补贴支持还是由监管框架强制实施，都必须价格低廉，才能被接受。设计的挑战是找到在典型应用程序中简单、健壮且成本低的方法。

The goal of this project is to develop low cost ways to remove methane from the ambient air. Many methane sources, such as emissions from cattle and other farming activities, and low-grade emissions from the gas industry, cannot easily be reduced. As a result, volumes of high-methane air persist around the sources. This proof-of-concept study will improve methods of locating such volumes of high-methane air, and also design and test simple inexpensive methane removal methods, such as soil methanotrophy in greenhouses, and catalytic removal of methane around gas installations, in order to develop new ways of reducing methane emissions from otherwise intractable sources. Methane is a potent global warmer, and is the second-most important anthropogenic greenhouse gas. Methane, which is rising rapidly at present, is emitted both by natural and anthropogenic sources, with about three-fifths of the emissions caused by human actions. These human-caused emissions include agriculture and waste (about a third of global total emissions), such as cattle breath and rice fields, landfills, and sewage systems, as well as fossil fuel sources such as gas leaks and coal mine venting. Many such sources are widely disseminated (e.g. cow breath) and thus regarded as intractable to reduction. Similarly, while larger gas and coal mine leaks can be identified and stopped, smaller disseminated leaks are harder to eliminate. Thus developing low-cost methods for removing methane from ambient air is a very important pre-requisite for reducing the global methane burden. But such disseminated emissions of high-methane air are not easily amenable to leak reduction efforts. The purpose of this proposal is to design and prove low cost ways of taking methane out of air, in ways that can easily be applied in settings where large amounts of methane are emitted. The aim is not to remove all methane, but to reduce mixing ratios of high-methane air where it is 'habitually' present.The first part of the work focuses on improving methods of detecting high-methane air in the ambient environment. This work will use mobile vehicle-mounted high-precision cavity-based analysers, coupled with grab sampling for high-precision isotopic analysis to identify the sources (e.g. using C-isotopes to distinguish gas leaks from nearby landfill gas emissions). The study will develop ways of quantifying volumes of high methane air in typical locations, and thus of assessing flow rates targetted for removal in ambient settings.In cow barns, feed lots and open milk sheds, the project will design and test methane reduction by using soil methanotrophy in active greenhouses next to the source. Methane-rich air will be extracted close to the source (for example from the mouths and noses of cattle in an open milking shed), and pumped under the substrate soil/growing medium of a greenhouse nearby. Here, methanotrophic bacteria will oxidise the methane to CO2, which will then be taken up by the plants in the greenhouse. The experimental work will test the feasibility of the method (e.g. energy costs) and optimise the conditions (temperature, humidity, air flow, etc).In industrial settings such as gas compressor sheds, or near large waste systems in enclosed spaces, removal by inexpensive chemical catalysis using MnO and CuO will be tested. These systems will be based on the reliable, low cost zero-air generators used in methane labs. The intention is not to remove all methane, but optimise economic partial-removal flow rates, optimal temperature and moisture conditions, frequency of regenerating the catalyst etc. The final part of the work will be in synthesis studies to assess the feasibility of methane reduction. An effective reduction policy, whether supported by subsidy or imposed by a regulatory framework, must be inexpensive to be acceptable. The design challenge is to find methodologies that are simple, robust in typical applications, and low cost.