New methodologies for removal of methane from the atmosphere

该项目的目标是开发低成本的方法来去除环境空气中的甲烷。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级排放，都不容易减少。因此，大量的高甲烷空气一直存在于污染源周围。这项概念验证研究将改进定位这种高甲烷空气的方法，还将设计和测试简单、廉价的甲烷去除方法，如温室土壤甲烷养殖法和天然气设施周围的甲烷催化去除方法，以开发减少原本难以处理的来源的甲烷排放的新方法。甲烷是一个强有力的全球变暖因素，是第二大最重要的人为温室气体。甲烷目前正在迅速上升，其排放既有自然来源，也有人为来源，其中约五分之三的排放是由人类行为造成的。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，以及天然气泄漏和煤矿排放等化石燃料来源。许多这样的来源被广泛传播(例如，牛的呼吸)，因此被认为难以减少。同样，尽管可以识别和阻止较大的瓦斯和煤矿泄漏，但较小的弥漫性泄漏更难消除。因此，开发低成本的方法去除环境空气中的甲烷是减少全球甲烷负担的一个非常重要的先决条件。但这种弥漫的高甲烷空气排放并不容易受到减少泄漏努力的影响。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排放大量甲烷的环境中。其目的不是去除所有甲烷，而是降低高甲烷空气的混合比例。第一部分工作重点是改进检测周围环境中高甲烷空气的方法。这项工作将使用车载高精度空腔分析仪，并结合抓取采样进行高精度同位素分析，以确定来源(例如，使用碳同位素区分气体泄漏和附近的垃圾填埋气排放)。这项研究将开发出量化典型地点高甲烷空气量的方法，从而评估环境中清除甲烷的目标流量。在牛舍、饲养场和开放式奶棚，该项目将设计和测试在源头附近的活动温室中使用土壤甲烷养殖物减少甲烷的方法。富含甲烷的空气将在接近源头的地方(例如，从开放式挤奶棚中的牛的嘴巴和鼻子中)提取，并泵入附近温室的基质土壤/生长介质下。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、空气流量等)。在工业环境中，如气体压缩机棚屋或封闭空间中的大型废物系统附近，将测试使用MnO和CuO的廉价化学催化去除。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。其目的不是去除全部甲烷，而是优化经济的部分去除流速、最佳温度和湿度条件、催化剂再生频率等。最后一部分工作将在综合研究中进行，以评估甲烷还原的可行性。一项有效的减排政策，无论是由补贴支持的，还是由监管框架强制实施的，都必须是廉价的，才能被接受。设计的挑战是找到简单、在典型应用中健壮且成本较低的方法。

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.