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OnderzoekESRIG - Energy and Sustainability Research Institute GroningenBasiseenheid Centrum voor Isotopen Onderzoek - CIOOnderzoek en projecten

PhD project: Independent verification and attribution of fossil CO2 emissions using atmospheric oxygen

Name: Elise Broekema

Supervisors:
Prof. dr. H.A.J. (Harro) Meijer (Centre for Isotope Research, ESRIG/RUG)
Prof. dr. W. (Wouter) Peters (Centre for Isotope Research, ESRIG/RUG)
Period: September 2016- August 2020

Summary of PhD project:

Climate change is a hot topic these days. Increasing levels of greenhouse gases, such as methane, nitrous oxide and carbon dioxide. Of these gases, carbon dioxide is the best known, the most abundant and the most studied. Its levels have strongly increased since the beginning of the industrial revolution. The atmospheric carbon dioxide levels have been measured at Mauna Loa, Hawaii since the late 1950s, this is shown in the famous Keeling-curve (fig. 1). In this figure, the red line depicts the actual measurements, it clearly shows seasonality, while the black line depicts the annual trend.

Figure 1. The Keeling-curve, which shows thecarbon dioxide levels measured at Mauna Loa, Hawaii.
Figure 1. The Keeling-curve, which shows thecarbon dioxide levels measured at Mauna Loa, Hawaii.

This increasing trend does not show where the carbon dioxide originates. It is known that the combustion of fossil fuels emits carbon dioxide, but so do amongst others combustion of biofuels, land use changes and wildfires. It can be calculated how much carbon dioxide has been emitted from several sources. This proves to be a lot more than the actual increase in the atmosphere. It was therefore concluded that not all of the carbon dioxide that was emitted ends up in the atmosphere: the biosphere and ocean are both large sinks too. The biosphere can store carbon through photosynthesis, and the ocean through photosynthesis and by acting as a solvent. In order to combat the consequences of increased carbon dioxide levels, climate change, we need to be able to distinguish between the different sources and sinks of carbon dioxide.

One way to distinguish between different sources of carbon dioxide is by measuring it together with oxygen. In many (life) processes, carbon dioxide and oxygen are coupled through a so-called stoichiometric ratio: for example with photosynthesis, when one mole of carbon dioxide is taken from the atmosphere, about 1.1 mole of oxygen is released into the atmosphere. Each process has its own specific ratio, which means that by measuring carbon dioxide and oxygen together, it is possible to calculate the ratio and use this to distinguish between sources.

A complicating factor is that measuring atmospheric oxygen is more complicated than measuring carbon dioxide, because the absolute differences are of equal sizes, but the background of oxygen is much larger. There are techniques to measure atmospheric oxygen, and the precision is still increasing.

In my PhD project, I will conduct and/or interpret carbon dioxide measurements at our measurement station in Lutjewad, from Antarctica, ánd we will set up a measurement station in the Rotterdam region, which is an urban region with high concentration of traffic and industry. Therefore, fossil emissions in this area will be high. Using these measurements and measurements of a colleague measuring radiocarbon, a model will be developed in which the carbon dioxide emissions from fossil fuels are quantified and analyzed. This model is than used as an emission verification system.

Last modified:22 May 2017 1.34 p.m.