v3.26.1
Cover - shares
 3 Months Ended
Mar. 31, 2026
May 07, 2026
Document Information [Line Items]    
Document Type 10-Q  
Document Quarterly Report true  
Document Period End Date Mar. 31, 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 320 Roney St.  
Entity Address, Address Line Two Suite 200  
Entity Address, City or Town Durham  
Entity Address, State or Province NC  
Entity Address, Postal Zip Code 27701  
City Area Code (919)  
Local Phone Number 287-4750  
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 Q1  
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   88,383,801
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