If the goal is to limit emissions…

In previous post, I left off concluding that the displacement of nuclear by natural gas will increase emissions. This based on the notion that displacing a low emission power source by one with a higher emissions will logically result in more emissions.

The big question is of course by how much? Not all nuclear capacity will be replaced by natural gas and solar and wind capacity will increase. To summarize, this is the change that is proposed:

  • Solar/PV: from 4787.56 MW now to 11 GWp by 2030
  • Wind
    • Offshore wind: from 2,254.4 MWp now to 4,000 GWp by 2030
    • Onshore wind: from 2,578.809 MWp now to 3,500 GWp by 2030
  • Natural gas: from 5,300 MW now to 5,600 MW
  • Nuclear: from 6,000 MW now to 0 MW.

Although the needed capacity of dispatchable power decreases very slowly compared the rapidly increasing peak production, the total amount of electricity produced by natural gas fired power plants will get smaller, therefor less emissions will be produced. This makes the dispatchable power sources less to not economical viable, but it might limit those extra emissions within reasonable bounds.

It might even be possible to find ways to lower emissions instead of limit them. There was an interesting response to the tweet of our Minister of energy. It was in French and if his twitter account information is truthful, the response came from an economist connected to an energy company:

Tweet @boisseleau6 2021-07-29

My French is a bit rusty and the author had to compress his response into 280 characters, but I think he is saying that wind power is “cheap” and therefor could be compensated for not producing at times of low demand:

Inexpensive electricity not much CO2, wind turbines that are compensated to stop because they are quite flexible. We should rather be happy. In any case, in a world with a lot of wind power, we will have to stop them from time to time (nuclear or not …)

He clarified even more in a response to the comment (in Dutch) that we are not at a point of “a lot of” wind today:

Absolutely, and it s not a problem, in the past we have stopped / reduced hydraulic, nuclear, gas and coal power stations when there is not a lot of demand. We will stop wind turbines tomorrow, no big deal, it is even an advantage, it s flexible, it can be easily stopped cheaply.

Indeed, other power sources currently stop or reduce their production when demand is low and wind also has that ability. I don’t really agree that wind energy is cheap, but in a later response he clarified that he was talking about the day-ahead price, so he didn’t mean actual cost or consumer cost.

This argument of curtailing (offshore) wind, just like the other power sources during low demand, is promising as it has the potential to even lower emissions.

That made me wonder whether I could pour this into a model and making some scenarios in order to compare what effect going zero nuclear would have on emissions. This is how this (simple) model is build:

  • Solar and wind data comes from the Elia website. The reference period is January until June 2021 (in order to avoid data from a covid year)
  • Demand: I will take total load data of the same reference period as demand.
  • Nuclear: I constructed it as ultimately rigid, it is always at the same level and budges for nothing
  • Natural gas: I constructed it as ultimately flexible and can go from 0 until its maximum capacity. It will try to fill in when solar + wind + nuclear don’t produce enough to meet demand and power back when they produce too much
  • Curtailing: when the combo wind/nuclear produces more than demand, gas will decrease its demand and if that doesn’t help, offshore wind will be curtailed
  • Exporting: if gas and offshore wind are 0 and there is still too much production, the rest will be exported
  • Importing: when solar + wind + nuclear + gas produce not enough, electricity will be imported.

One thing that still missing are emissions. Our Minister of Energy called wind power “emission free” and in that case it would be logical to prioritize it and reduce production of other (not emission free) power sources in order to reduce emissions. But the same could be said about nuclear power. Just as wind, it produces no emissions during its operation. Both wind and nuclear have life-time emissions though. These are the median life-time emissions of solar, wind, nuclear and gas according to the IPCC:

Technology Emissions (g CO2 eq./kWh)
Gas 490
Nuclear 12
Solar (rooftop) 41
Solar (utility) 48
Wind (offshore) 12
Wind (onshore) 11

These are emissions that will get into the atmosphere and we should take them into account. Natural gas sticks out way above the rest. Nuclear and wind are comparable. I don’t know what the exact share of rooftop/utility solar is, so in my model I assume a value between the two (45 g CO2 eq.).

I also will add a scenario with limited nuclear (a suggestion of the opposition to keep 2 nuclear turbines online) and two fairy tale scenarios with nuclear at the current capacity, but with the projected capacity of solar and wind in combination of more or less natural gas.

These are the capacities that I used in the scenarios that I looked into:

Scenario Solar Offshore wind Onshore wind Nuclear Natural gas Demand
1. Current situation (control) Current Current Current 6,000 MW Max. 5,300 MW Current
2. Forecast capacity in 2030 with limited nuclear 11,000 MWp 4,000 MWp 3,500 MWp 2,000 MW Max. 7,600 MW Current
3. Forecast capacities in 2030 without nuclear 11,000 MWp 4,000 MWp 3,500 MWp 0 MW Max. 7,600 MW Current
4. Forecast capacities for solar and wind in 2030 with current nuclear and gas 11,000 MWp 4 GWp 3,500 MWp 6,000 MW Max. 5,300 MW Current
5. Forecast capacity for solar and wind in 2030 with current nuclear, but less gas capacity 11,000 MWp 4,000 MWp 3,500 MWp 6,000 MW Max. 2,300 MW Current

Without further ado, this is what the model spitted out for the different scenarios for the reference period:

Scenario Total emissions (ton CO2 eq.) Curtailed (MWh) Exported (MWh) Imported (MWh)
1. Current situation (control) 4,960,066 371,100 11,4781 49,688
2. Forecast capacities in 2030 with limited nuclear 9,905,273 275,690 117,448 372,829
3. Forecast capacities in 2030 without nuclear 12,936,442 59,573 7,570 2,338,861
4. Forecast capacities for solar and wind in 2030 with current nuclear and gas 3,495,707 2,114,457 1,842,799 27,074
5. Forecast capacity for solar and wind in 2030 with current nuclear, but less gas capacity 2,843,771 2,114,457 1,842,799 1,357,556

Comparing scenario 1 with scenario 3, it becomes clear that there are less emissions in the current situation (nuclear + solar + wind + natural gas) than in the zero nuclear scenario (solar + wind + natural gas). The difference in this model is almost 8 million ton CO2 eq. for the 6 months of the reference period. This means about 15 – 16 million ton for one year in this model, that is about 12% of the Belgian emissions. That is not a small detail.

Most importantly, the model calculated lower emissions in those scenarios that had nuclear in the power mix. The scenarios that include nuclear are superior when it comes to emission reduction, but have huge amounts of curtailment and export. The more nuclear, the less emissions, but the more curtailment and export. The more gas, the more emissions, but the least import.

The scenario without nuclear has the highest emissions, but is superior when it comes to curtailment and export. It has by far the lowest curtailment of wind (what our Minister wanted to communicate with her tweets) and by far the lowest export, but it heavily depends on import (increased import capacity is indeed part of her plan).

This is just a crude model and it doesn’t pretend to show exactly what will happen in 2030, but it gives some indication that eliminating nuclear will result in more emissions.

The Greens are not the Greens they were before. Roughly a year ago I wrote a post on the same member of the Green party (before she became Minister of Energy) increasing “fossil fuel subsidies” and being patted on the back for it. Now she is Minister of Energy and has an energy plan that will increase emissions substantially, she again get cheered for it…

2 thoughts on “If the goal is to limit emissions…

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