Topic: Skyrocketing exports when optimizing with OSeMOSYSSubscribe | Previous | Next
Anastasios Karamaneas 3/17/2022
Dear LEAP community,
I'm trying to get familiar with the optimization feature of LEAP and I'm facing a crucial issue. I set up my demand and transformation branches and I choose to optimize using the OSeMOSYS option. When I run the simulation (with 2020 as my base year) the model decides to almost double the electricity generated for 2021 (and the following years) and drive all the surplus energy to exports which leads to double electricity generation from every plant that I have inserted, doubling the emissions for no apparent reason.
PS: I am working with a single-region Area so the exports do not go to any other region of the exercise.
Thank you
Jason Veysey 3/21/2022
Hi, Anastasios -
Based on what you wrote, I'm not sure why this is happening, but I'd suggest checking that you have realistic costs defined for the optimization model.
I'd also check the results with NEMO - this is the primary optimization tool for LEAP and offers better performance and functionality than OSeMOSYS. You can download an installer for NEMO from the Download link on this site.
Thanks,
Jason
Anastasios Karamaneas 3/21/2022
Hi Jason,
I have tried NEMO as well and I have exactly the same issue and because after my first NEMO attempt I had some other issues, I decided to return to OSeMOSYS since my initial issue was not solved.
Regarding the costs that you mentioned, I have set zero (and even negative) profits for exporting in order to refrain the optimization from exporting electricity but it didn't help. Do you know if I can somehow block electricity exports? (There are not useful anyway in the optimization that I want to examine).
Thank you,
Anastasios
Jason Veysey 3/23/2022
Hi, Anastasios -
Without knowing more about your model, I'm afraid it's hard to say why you're getting this result. I will observe, though, that this isn't an export problem so much as a production problem. OSeMOSYS is producing more than you want, and LEAP is choosing to export the surplus (rather than waste it) because this is how your model is configured.
I suggest simplifying the model and adding back complexity a little at a time until you trigger the problem. This will help you pinpoint the source. For example, try dropping or zeroing out all processes except one, then add processes back one at a time. This could reveal if there's an issue with, say, excessive capacity of zero marginal cost production.
Thanks,
Jason
Anastasios Karamaneas 3/24/2022
Hi Jason,
In my model I'm trying to simulate the Greek energy sector, therefore I have added every fossil fuel and hydro power plant separately (to have better control of there availability, capacity etc), plus RES power plants per type of primary energy source (solar, wind, biomass) and I have also created a thorough demand branch.
Regarding your suggestion to drop/zero all the processes and adding them one at a time, I have tried the opposite. I tried zeroing one process at a time and I had to zero many process until production met the demand requirements without having surplus electricity generation.
If it could be of any help, could I attach my model so you can have a better understanding of what is going on?
Thank you very much,
Anastasios
Jason Veysey 3/24/2022
Hi, Anastasios -
Yes, that would be helpful. You could attach it to a message here or email it to me at jason.veysey@sei.org. I'll have a quick look to see if I can determine why there's excessive production.
Regards,
Jason
Anastasios Karamaneas 3/24/2022
Hi Jason,
Thanks again for your swift responses. I'm attaching the LEAP file here. Hope it helps.
Note: The process "Wind on islands" is separate because many Greek islands are not yet interconnected to the Greek mainland transmission network, thus their costs would be slightly higher and I would like to have the "freedom" to examine how wind energy can be deployed in Greek islands if necessary.
Many thanks,
Anastasios
Greece.leap [2]
Jason Veysey 3/24/2022
Hi, Anastasios -
Thanks for providing a copy of your model. I looked through it and found the source of the excessive production. The root cause is an issue with how LEAP writes inputs for optimization when an optimized module has multiple output fuels. This is the case in your model - your optimized module's output fuels include both electricity and heat. The issue occurs when using NEMO and OSeMOSYS, as you reported.
We are working on correcting it and should have a fix in an upcoming release of LEAP. In the meantime, you can work around the issue by converting heat to a module co-product rather than a regular output fuel. To do this, delete the output fuel for heat, specify heat as the co-product in the optimized module's properties (see the screenshot below), and populate the new Coproduct Efficiency variable for the module's processes.
Although I'm characterizing this approach as a work-around, I think it's preferable from a conceptual standpoint as well as on practical grounds. Right now, your model assumes that any process in the optimized module can produce heat, including non-thermal processes such as hydro and solar PV. With Coproduct Efficiency, you can instead control which processes generate heat and how much they produce relative to their electricity output.
I hope this is helpful. Thanks for finding this issue for us!
Regards,
Jason
Anastasios Karamaneas 3/25/2022
Hi Jason,
This worked great!! I would have never thought of checking this matter. Thank you very much for your very useful help!!
Best Regards,
Anastasios