Carbon Emission reporting has become mandatory in the European Union, and many countries are following that lead. How are these emissions being calculated? What are the assumptions behind these numbers? How accurate are they?
I recently joined a non-profit, Ribbit Network, to lead their outreach effort and start getting more involved in the climate space. Ribbit Network is deploying a global network of CO2 sensors to collect real time Green House Gas (GHG) concentration and share these observations with the broader community. The entire project is open source and its data is publicly available. This was a really good opportunity for me to get some hands on experience.
This led me to investigate what are the current approaches in place to measure GHG emissions. I honestly thought that problem had already been figured out by research programs world wide. I was surprised that it was far from true.
The first issue is that most of the GHG reporting mandated today by governments around the world is self-reported by industries. That reporting is shrouded with opacity, and most often doesn’t follow a uniform standard. So there is certainly a need to perform some level of independent monitoring to validate these reports.
From the technology standpoint, there are several ways to approach the GHG measurement problem: satellite monitoring, focusing on macro level measurements, and ground level monitoring, looking at the local level measurements. On top of these, there are many calculations based on assumptions and hypothesis to make sense out of the raw measurements.
Before we get started on this analysis, it is important to recap what are the biggest anthropogenic (caused by humans) sources of emissions:
- Fossil fuel power plants: coal, oil and gas
- Fossil fuel consumption: transportation, heating and cooling, industrial processes
- Agriculture
- Biomass and biofuel burning (this one could be both a natural and human caused flux. For example: forest fires).
- Landfill and waste water treatment plants.
Another important terminology point: GHG include CO2 and also CH4, NO2 plus a number of others. Typically, the report will provide a “CO2 equivalent” measurement in metric ton, to simplify the reading.
Macro level: Satellite monitoring
Satellite technology use a constellation of satellite orbiting the earth to take sample measurements using spectrometer technology.
CO2 lingers around in the atmosphere for many years, and there are seasonal variations due to the natural cycles of plants and phytoplankton. These emissions are filtered out to showcase only the human made emissions.
Satellite technology tends to focus on the biggest emitters (macro level). They identify “priority areas” that will be covered in their data collection. These include oil and gas production fields, pipelines, refineries, power plants, regions with large concentrations of livestock and urban areas where landfills, wastewater treatment plants and natural gas distribution systems are common.
Their benefits are to cover a global territory, and get a good picture of the biggest known emitters of GHG.
NASA’s Orbiting Carbon Observatory-2 (OCO-2) was launched in 2014 and measures CO2. Its instrumentation is on board the International Space Station.
Greenhouse Gases Observing Satellite is a Japanese program that launched in 2018. It measures CO2, CH4, CO and NO2
The Copernicus Earth observation program is a European union initiative that will start monitoring carbon emissions in 2025
Challenges and Limitations
The cost of these programs range in the millions of $. The NASA OCO-2 program cost about $464M to design, launch and operate.
They also take a long time to deploy or upgrade (years to decades).
They provide a daily to weekly sampling, but not more granular.
They have limited resolution at the local level.
Local level: Ground based monitoring
Ground based monitoring stations have by nature a more limited geographical coverage. They are mostly deployed around urban centers or colocated with industrial facilities. Some of these measurements can be recouped with Satellite observations to validate findings.
Technology uses optical laser (NDIR or Non Dispersive InfraRed) and spectroscopy to measure the CO2 concentration, measuring % of CO2 in air or part per million (ppm). Typical CO2 levels currently observed are around 400ppm (0.04% CO2).
Stations are usually connected to a WiFi network that provides connectivity to the cloud for data upload and OTA (Over the Air) software updates.
The different types of stations include commercial offerings, university research projects and citizen networks.
Commercial offerings:
Most ground monitoring stations are using commercial products. They are typically deployed in and around large urban areas. These systems are highly accurate.
Challenges and Limitations:
- No real time system for accessing the data.
- Monitoring sites are difficult to maintain overtime
- Expensive: $15k in average per unit in average
- Limited deployment scope.
- Proprietary data/measurements.
Commercial companies collecting CO2 Emissions:
Many of these closed-source private endeavors are focused on air quality data, since that’s where they see most of the commercial demand. GHGs are less of a priority for these companies. For example, Aclima has mobile sensors (on cars) to try and collect some GHG data, though only a small amount of this data is public and little of it is real time.
University Research projects:
R&D Labs in several universities have deployed small scale networks usually around their campus. Sensors are of high quality. Data collection and method are usually public; however, the scientific publications are written for an audience of other scientific experts. This makes the findings difficult to decipher for the average reader.
Examples:
- Berkeley BECO2N project
- MUCCNet, operated by the technical university of Munich
Citizen networks:
These sensors can be deployed at relatively low cost and scale overtime. they use a laser technology (IR) to measure the CO2 concentration. They are deployed by volunteer citizen scientists.
Ribbit Network is an open source project with a sensor Bill Of Materials for less than $250. That includes the CO2 sensor itself, a temperature and humidity sensor, an ESP32 microprocessor, a GPS and a barometer. The full sensor assembly is straight forward and can even be accomplished by college students as a learning experiment.
They are useful for detecting unknown sources of GHG, providing a micro-level assessment of GHG emissions and offer a high sampling frequency (near real time monitoring). These networks also have an educational purpose, since students can be exposed early on to climate science.
Challenges and Limitations:
- Limited coverage unless you deploy thousands of sensors.
- Maintenance and operation, and long time to deploy at scale.
- At scale deployment can be costly as well, but can be phased overtime (incremental)
- Getting to acceptable degree of accurate measurement (calibration) is difficult due to the limitations of current/low cost hardware.
Combining all the Sources: Data aggregation
GHG computation systems identify anthropogenic emissions from natural sources (normal diurnal cycles of plant breezing, ocean warming and cooling). The final intent is to derive trends and insights on human-caused carbon emissions and correlate these trends to specific climate actions.
While some systems just use estimates to compute human caused carbon emissions, most use the known locations of largest polluters, combined with sensor concentration data and meteorological data to calculate and aggregate anthropogenic carbon emissions.
There is no perfect system to measure GHG concentrations, so the future of GHG monitoring is to combine and aggregate data from different sources. On the back end side, an open API would help with the integration of new monitoring technologies. On the front end side, the presentation of the information is critical, so that it can be shared with the wider community (beyond scientists).
How do you guarantee openness and transparency?
Another key aspect is the openness and transparency of the organization that owns the reporting system. An independent and non-profit entity, such as Climate Trace, that validates emissions reported by various industries and companies. Currently, the IPCC only provide guidelines for governments to produce their own GHG inventory. Ideally, emissions reported by independent third party could be certified by the IPCC. The future will tell if/how that will happen.
The technology and science behind measuring carbon emissions can get pretty complex and are still evolving. If you are interested to get some hands on experience with a simple approach, I invite you to check out Ribbit Network. This is a great way to get started!
