Explainers

Methane Point Sources — What They Are and Why They Matter

Published on: Aug 28, 2023

This post is part of Carbon Mapper’s Methane Remote Monitoring Education Series, which intends to help build a base knowledge of important topics in the methane monitoring space and demystify key concepts that are important to Carbon Mapper’s mission. To recommend a future topic, contact us here.

Introduction

As we covered in our last post, methane is a super-potent greenhouse gas released into the atmosphere from a variety of sources and processes across different sectors. They can come from natural sources, like wetlands, termites, or wildfires. Or, they can come from anthropogenic (human-caused) sources like agriculture, oil and gas operations, or landfills and dumpsites.

Knowing exactly where these emissions come from is important because it has a big influence on how they can be identified, quantified, tracked, and ultimately — mitigated.

Generally, there are two main categories of methane emissions: point-sources and area sources. In this post, we look at the differences between the two and why they matter in the context of increasing methane emissions transparency and driving mitigation.

Why differentiate between point sources and area sources?

Both methane point and area sources contribute to regional emissions; however, point sources are often large methane emission events localized to discrete pieces of infrastructure or facilities. Meanwhile, area sources are also large, but they are spread over a wide area. Identifying which types of sources are contributing to regional emissions can help to prioritize the most effective mitigation solutions.

This graphic shows and example of point sources versus area sources of methane emissions.

Strong methane point sources can have an outsized climate impact

To address climate change, both point and area sources need to be addressed. Remote sensing can be used to measure and monitor both types, but it also offers a unique opportunity to identify strong methane point sources and help us achieve significant methane reductions quickly.

The reason for this is because, in some places and for some sectors, point sources can make up a large proportion of a basin or region’s total emissions. For example, oil and gas operations are the largest source of methane emissions from the energy sector. Studies have found that on average, 20%–60% of emissions from US oil and gas basins originate from a very limited number of strong point sources.

Additionally, this disproportionate contribution of point sources to regional emissions has been found across many sectors including coal and waste. For example, in a surveyed area of the Marcellus basin in southwestern Pennsylvania, 58% of observed methane in the region was attributed to point sources primarily due to the practice of coal mine ventilation.

Detecting point sources: How they are measured and how this data can be used

Some measurement and monitoring tools are best suited to area mapping (i.e.,detecting and quantifying emissions at national and regional scales). Other tools are optimized for point source mapping (i.e., identifying emissions down to the scale of individual facilities and equipment). And others still can do portions of both. These different capabilities help to support different use cases.

The key to addressing point sources quickly is being able to identify them, and a variety of stakeholders are interested in accessing transparent, timely, and accurate data that can be applied in different ways. For example:

Operators of oil and gas, waste, or agricultural facilities: By identifying the exact source of emissions, like a leaking pipe or malfunctioning piece of equipment, operators can quickly diagnose the problem, and fix it often using readily available and cost-effective measures or technologies.
Regulators and policymakers: Data can improve compliance or help them understand where policy gaps might exist. For instance in our coal example above, coal mine venting in many cases is an expected and permitted operation, but understanding the sector’s impact on total regional and national greenhouse gas emissions can help to understand the implications of this policy and inform solutions on how to address these emissions.
Community groups and health advocates: Many aim to gain visibility on the strong local emissions point sources to design unique solutions that address community concerns and improve public health.

Knowing what you want to measure, and how this data will be used, is key to selecting the best technological solutions to pinpoint, quantify, and track point source emissions. Handheld cameras, stationary monitoring stations, airborne observations, and methane sensing satellites are just a few of the ways stakeholders are monitoring methane today. And among these technologies, there are a variety of factors (like their detection threshold, sampling frequency, and spatial coverage) that impact how effectively or ‘completely’ they can detect point sources, a topic that we’ll cover in a future post.

Carbon Mapper is focused on detecting and quantifying large emissions point sources (so far through our airborne surveys and soon via satellites being developed in partnership with Planet Labs PBC and NASA JPL) and providing that information in an actionable and accessible way. Our goal is to fill data gaps in the emerging global ecosystem of methane and CO2 monitoring systems by delivering data at facility scale that is precise, timely, and accessible to empower science-based decision making and action.

The image below offers examples of the types of point sources across multiple sectors Carbon Mapper has observed during its airborne surveys. Carbon Mapper surveys to date have covered all major methane-emitting sectors across high priority regions in North and South America, and the Carbon Mapper Data Portal includes methane plumes from countries around the world.

Strong point sources of methane emissions come from a variety of sources and processes across different sectors. This graphic shows examples of methane plumes available on the Carbon Mapper Data Portal.

Detecting Methane Point Sources Over Water

Point sources of methane don’t just exist on land; they can also be found over water — particularly with offshore oil and gas operations. Few studies have directly measured methane emanating from these platforms due to their remote location compared to onshore production, and technological challenges of observing methane emissions over water (the dark surface limits the sun’s reflection hindering methane measurements). Between spring and fall 2021, Carbon Mapper and other research partners conducted the first systematic application of a remote emissions-sensing technology that can detect methane emissions over water, and attribute methane emissions to specific infrastructure, observing 151 shallow water offshore oil and gas platforms in U.S. state and federal waters in the Gulf of Mexico. The team found that the methane loss rate from these shallow water sources is significantly higher than typical onshore production and disproportionally contributes to climate change—providing a potential focus for sustained monitoring and mitigation efforts.