FORM 10-Q QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the quarterly period ended June 30, 2026ORTRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from ______ to ______ Commission File Number 001-40503 NET Power Inc. (Exact name of registrant as specified in its charter) Registrant’s telephone number, including area code Securities registered pursuant to Section 12(b) of the Act: Indicate by check mark whether the registrant: (1) has filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of1934 during the preceding 12 months (or for such shorter period that the registrant was required to file such reports), and (2) has been subject to suchfiling requirements for the past 90 days. YesNo Indicate by check mark whether the registrant has submitted electronically every Interactive Data File required to be submitted pursuant to Rule 405of Regulation S-T (§232.405 of this chapter) during the preceding 12 months (or for such shorter period that the registrant was required to submitsuch files). YesNo Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, a smaller reporting company, oran emerging growth company. See the definitions of “large accelerated filer,” “accelerated filer,” “smaller reporting company” and “emerging growthcompany” in Rule 12b-2 of the Exchange Act. If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with anynew or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. Indicate by check mark whether the registrant is a shell company (as defined in Rule 12b-2 of the Exchange Act). YesNo The registrant had outstanding 88,480,681 shares of Class A Common Stock and 136,377,880 shares of Class B Common Stock as of August11,2026. TABLE OF CONTENTS Certain Defined Terms For the definitions of certain defined terms used throughout this Quarterly Report on Form 10-Q (this “Report”), pleaserefer to the section entitled “Certain Defined Terms” in our Annual Report on Form 10-K for the fiscal year endedDecember31, 2025 (the “Annual Report”).Capitalized terms used but not otherwise defined in this Report have themeanings assigned to them in the Annual Report. In addition, the following terms are used in this Report: •“Entropy PCC Technology” means the proprietary solvent-based post-combustion carbon capture technology ofEntropy Inc., which Entropy markets as its modular carbon capture and storage solution. On November 7, 2025,the Company and Entropy entered into a letter of intent, non-binding except for certain customary provisions,contemplating the negotiation of one or more definitive agreements under which the Company and Entropy wouldhave jointly developed an application of Entropy PCC Technology for use in combined cycle gas turbine powerplants, deployed Entropy PCC Technology on an exclusive basis for power generation applications in the UnitedStates, and jointly developed projects utilizing such developed technology. That letter of intent has expired by itsterms and has not been replaced. The Company has not entered into a definitive agreement for the license of PCCtechnology, and either party may discontinue negotiations at any time. See Part I, Item 2, Management’sDiscussion and Analysis of Financial Condition and Results of Operations. •“Post-combustion carbon capture” or “PCC” means the capture of carbon dioxide from the flue gas of acombustion process, including through the use of chemical solvents. Cautionary Note Regarding Forward-Looking Statements This Report contains “forward-looking statements” within the meaning of Section 27A of the Securities Act and Section21E of the Exchange Act. Statements that do not relate strictly to historical or current facts are forward-looking andusually identified by the use of words such as “anticipate,” “believe,” “could,” “estimate,” “expect,” “forecast,” “future,”“intend,” “may,” “opportunity,” “plan,” “potential,” “project,” “seek,” “should,” “strategy,” “target,” “will,” “will likelyresult,” “would” and other similar words and expressions, but the absence of these words does not mean that a statement isnot forward-looking. Forward-looking statements may relate to the anticipated demand for the Company’s products andservices, the Company’s ability to license third-party technology, the development and financing of the Company’s powergeneration projects, the timing and configuration of project phases, grid interconnection, the Company’s businessstrategies, capital requirements, potential growth opportunities and expectations for future performance (financial orotherwise). Forward-looking statements are based on current expectations, estimates, projections, targets, opinions and/orbel