linear Fresnel annual electric output higher than parabolic trough for same climate input file

I am receiveing higher than expected annual electric output for the linear fresnel model I am using.

Is there a possible reason for this? Can it be an error in my input settings?

Or could it be a bug?

Thanks,
Jonathan

Hi Jonathan,

Would you mind posting a reply with a copy of your .zsam file attached, and some more detail about what results you are expecting?

Best regards,
Paul.

Hi Paul,

Do you perhaps have an idea why this model is not accounting for the optical efficiency losses expected from a LFR?

Thanks,
Jonathan

Hi Paul,

Thanks for replying so soon.

I attached the .zsam file in my first post but I'll do it again now. (not sure if it worked)

In the file I'm comparing power tower, parabolic trough, dish-Stirling and linear Fresnel.

I'm setting the design parameters as similarly as possible so I can compare the net annual electric output, water usage, land usage, capacity factor, etc.

When I run the simulations. I get the following net annual electric outputs:
Power Tower: 404,181 MWh
Parabolic Trough: 301,346 MWh
Dish-Stirling: 227,118 MWh
linear Fresnel: 393,984 MWh

It appears to me that the linear Fresnel result is too high. I'm using the same climate input file for all the cases so I'm not sure why the CLFR (linear Fresnel) annual output is so high.

Do you perhaps have an idea why it can be this high?

I'll attach the file and the climate input file below.

Thanks Paul.

Kind regards,
Jonathan

Hi Jonathan,

It seems the linear Fresnel output is higher than might be expected because the fossil backup (Power Cycle page -> fossil fill fraction) is guaranteeing nominal power block output throughout most of the day. This design removes some of the advantage that thermal storage provides the molten salt technologies. Note that when all fossil fill fractions are set to 0 for the linear Fresnel model, the annual output decreases significantly.

The calculated optical efficiency can be displayed by selecting it from the outputs listed in the column on the right when viewing “Time Series” results.

Regards,

Ty

Hi Ty,

Thank you so much for your reply. Do I understand you correctly if I say that because the trough and tower models use fossil backup to charge their thermal energy storage tanks they do not produce electricity at nameplate capacity. However because the CLFR simply uses it to supplement turbine operation only as it has no storage, it can operates at nameplate capacity from morning till evening. ?

The problem I have with changing the fossil fill fraction on the CLFR and not the parabolic trough and power tower is that my comparison of the technologies is then somewhat skewed as I am not using the same power dispatch schedule to rank all the technologies. This doesn't give an equal footing to the technologies I'm comparing, as I am fixing power dispatch schedule across the board to see which annual output is highest for that power dispatch schedule, plant availability, plant degradation, aperture area (more or less), etc.

How do you suppose I equitably compare the technologies? Reduce the fossil fill fraction to 0.5 across the board?

Regards,
Jonathan