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Average and Marginal CO2eq emission factors

Online seminar was recorded and is now available for watching below

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Published Feb 22, 2021

On Friday the 4th, a seminar/discussion about Marginal and Average CO2 eq emission factors took place online. It had been organized by EGI PhD students to try to get a better understanding of this topic. The chairperson of the event was Viktoria Martin.

This seminar was a two part event, the first one consisting of different speakers presenting some aspects of the question and the second being an open discussion, primarily between speakers but also involving the public.

First, Monica Arnaudo gave a general introduction on the background of this seminar as well as the different speakers.

Johan Dalgren then presented why this topic is so important for us at EGI taking his own research as an example. He zoomed in the topic from the global energy supply, eventually reaching Stockholm District Heating network.

In a few graphs, he introduces key points, such as the merit order curve for DH systems (which, as an interesting fact, changes with electricity price). He explained why it was important to consider the emission factors of electricity when dealing with heat, since the two are to a large extent here in Sweden, interlinked.

He then opened the discussion by asking a series of questions to the following speakers.

Lennart Söder, professor at the Division of Electric Power and Energy Systems here at KTH gave a presentation entitled “My electricity: Where does it come from?”. He reminded how the electrical system works by giving 8 different ways of answering this question. Those different points of view could be recapped as follow:

  • Short term (seconds) physics

This first point was an explanation of the way the system works on short time scales.

  • Short term (hours) marginal impact

Then, Lennart explained the way it functioned on longer time scale, and how does the market allocate the means of power productions.

  • Impact from emission trading

This point was a reminder on the emission trading system and how it impacts the power grid emissions on the European level.

  • Geography

Here, he focused on one approach stating that what one consumes corresponds to the closest production. The limits of such point of view were highlighted.

  • Electricity certificates.

There is a system implemented by Swedish Parliament to finance units. The system has been implemented in 2003 and is to run until 2030. This is another way of claiming a particular electricity.

  • Guarantee of Origin

Then, Lennart talked about the GoO market system in some detail and explained why, even if it is on paper a good system, its current layout leads to double counting effect which allow everyone to claim they are green.

  • Investments

One can also claim he is “green” because he invest in such business. However, it doesn’t prevent them from selling the GOO anyway, thus conflicting with the previous system.

This is yet another standard.

  • Long term marginal impact

To explain this, the Hybrit project was taken as an example. They assume that in the long run, because of the increase in consumption they will induce, more wind power will be needed, hence what they consume will come from wind.

Finally, he gave a list of Swedish companies examples claiming they are green and analyze their claim based on the previous points.

Then an interesting exchange on what is marginal paved the road to Erik Dotzauer’s and John Clauss’s presentations.

If readers are interested in learning more on the topic, they will find Lennart’s presentations here (row 34)

Erik Dotzauer then gave a presentation entitled “Climate assessment of energy systems”.

In a first part, he explained why climate assessment of energy was important from his point of view, which as Johan was the District Heating industry, it processes energy from different sources and types and outputs it in other form (heat and electricity).

Then he turned to the main part of his presentation, which was about the different methods to conduct such impact analysis:

  • The first dimension being whether we talk about future impact or past ones
  • The second one referring to either consequential (what will be the effect of) or bookkeeping approach (which part am I responsible of)

This distinction created a very clear framework for the discussion. It was very valuable to the rest of the seminar, when talking about GoO for example (which belong to bookkeeping and past impacts according to this classification).

It was also used by Erik himself when he discussed the nature of the marginal electricity in Sweden. Erik ended his presentation by highlighting that one cannot make the analysis within a single hour, since hydropower stores energy over seasons. The conclusion was that fossil power is probably on the margin during the whole year, even in the summer season. 

John Clauß, gave a presentation entitled “A generic methodology to evaluate hourly average CO2eq intensities of the electricity mix”.

His presentation was divided in several parts:

First he presented his background on the topic and the reasons that brought him to study this topic. Mostly, he initially wanted to evaluate the average carbon intensity of electricity in order to use it as a control signal for building demand.

Then he presented the model he introduced the model he used to determine this intensity, together with its assumptions and limitations.

For the results, John presented them in a visual way, thus helping to understand the somehow counter intuitive conclusions he reached to.

He later discussed the use of such signal for energy system control and the strengths and weaknesses of the approach.

Finally he concluded on the methodology and use of average CO2 intensity in a broader way, reflecting on it in other contexts than Norway and Nordic countries.

Finally, we had Olivier Corradi, from Tomorrow (the company behind the electricity map) as our last speaker.

First, he presented briefly the method they use at Tomorrow to assess the marginal emission factors.

To this end, Olivier first explained how they assess the average emissions factors and secondly, he explained how the marginal factor estimation was carried. One key point from this short presentation was that, even if it was of course too short to detail every aspect of the methodology, the assumptions of the model were explicited very transparently.

Please refer to this other presentation for an in depth and more faithful description of the methodology used by Tomorrow:

Then he answered a series of questions asked by the public, both from the live and prepared in advance on different topics, like uncertainty assessment, hypothesis on the emission factors, and so on.

After this and a little break, it was time for a more open discussion. Several topics have been brought up, but most of the discussion was focused around relevant signals for demand management. Price, marginal and average emissions factors have been discussed.

Page responsible:Oxana Samoteeva
Belongs to: Energy Technology
Last changed: Feb 22, 2021