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I watched the work of the English on the subject https://research.birmingham.ac.uk/porta ... ovelli.pdf
And I found the flaw: the E. Dupont process uses the cooling of the trigger to improve performance. OK fine.
The big problem is to liquefy. On the diagram above I have put in blue the temperatures on the exchanger: 300K at the compressor outlet, then 96 K at the outlet of the exchanger. And then am the regulator.
When you don't have the very cold source, you get shitty performance. I took the data from commercial LN2 liquefiers, and it turns out in the 10% range. It is in the 2,5 kWh per liter consumed against the theoretical 250 Wh.
As the English study clearly explains, you need to store 3 things to make storage:
- a cold source at 77K - 9200 m3 of rocks for a 70 MW compressor
- a hot source at 375 ° C (648K) - 4000 m3 of high temperature oil
- liquid nitrogen
When liquid nitrogen is produced, the hot source (compressor outlet) is charged and the cold source is discharged (just before liquefaction).
When energy is produced, the cold source is charged and then the hot source is discharged to reach 370 ° C before the final turbine.
Under these conditions, a yield of 60% is achieved.
As I see it, the E. Dupont process may have 70% efficiency at discharge, but not more than 10% efficiency at load. I concede up to 25% to the load on very large units.
And therefore 17% overall AT THE BEST.
If the cold of the expansion is not stored, the liquefaction efficiency is catastrophic. And if we use the cold to improve performance, we no longer have it. CQFD
