v3.26.1
Cover - shares
 3 Months Ended 6 Months Ended
Jun. 30, 2026
Jun. 30, 2026
Aug. 11, 2026
Document Information [Line Items]      
Document Type   10-Q  
Document Quarterly Report   true  
Document Period End Date   Jun. 30, 2026  
Document Transition Report   false  
Entity File Number   001-40503  
Entity Registrant Name   NET Power Inc.  
Entity Incorporation, State or Country Code   DE  
Entity Tax Identification Number   98-1580612  
Entity Address, Address Line One   11700 Katy Freeway  
Entity Address, Address Line Two   Suite 700  
Entity Address, City or Town   Houston  
Entity Address, State or Province   TX  
Entity Address, Postal Zip Code   77079  
City Area Code   (888)  
Local Phone Number   323-6797  
Entity Current Reporting Status   Yes  
Entity Interactive Data Current   Yes  
Entity Filer Category   Non-accelerated Filer  
Entity Small Business   true  
Entity Emerging Growth Company true    
Entity Ex Transition Period false    
Entity Shell Company   false  
Entity Central Index Key   0001845437  
Document Fiscal Year Focus   2026  
Document Fiscal Period Focus   Q2  
Current Fiscal Year End Date   --12-31  
Amendment Flag   false  
Class A Common Stock      
Document Information [Line Items]      
Title of 12(b) Security   Class A Common Stock  
Trading Symbol   NPWR  
Security Exchange Name   NYSE  
Entity Common Stock, Shares Outstanding     88,480,681
Warrants, each exercisable for one share of Class A Common Stock at a price of $11.50      
Document Information [Line Items]      
Title of 12(b) Security   Warrants, each exercisable for one share ofClass A Common Stock at a price of $11.50  
Trading Symbol   NPWR-WT  
Security Exchange Name   NYSE  
Class B Common Stock      
Document Information [Line Items]      
Entity Common Stock, Shares Outstanding     136,377,880