# EDGAR Filing Document

**Accession Number:** 0001845437
**File Stem:** 0001845437-25-000032
**Filing Date:** 2025-6
**Character Count:** 5045
**Document Hash:** 1be3baff979a716135c3f5a429323a13
**Contains OCR:** False
**Source Format:** 

## Filing Content

## Filing Summary
**0001845437-25-000032.hdr.sgml**: 20250604

**ACCESSION NUMBER**: 0001845437-25-000032

**CONFORMED SUBMISSION TYPE**: 3

**PUBLIC DOCUMENT COUNT**: 1

**CONFORMED PERIOD OF REPORT**: 20250415

**FILED AS OF DATE**: 20250604

**DATE AS OF CHANGE**: 20250604

**REPORTING-OWNER**: 

**OWNER DATA:**
- **COMPANY CONFORMED NAME:** Horstman Marc
- **CENTRAL INDEX KEY:** 0002070734

**ORGANIZATION NAME:**

**FILING VALUES:**
- **FORM TYPE:** 3
- **SEC ACT:** 1934 Act
- **SEC FILE NUMBER:** 001-40503
- **FILM NUMBER:** 251024863

**MAIL ADDRESS:**
- **STREET 1:** 320 RONEY STREET
- **STREET 2:** SUITE 200
- **CITY:** DURHAM
- **STATE:** NC
- **ZIP:** 27701
**ISSUER**: 

**COMPANY DATA:**
- **COMPANY CONFORMED NAME:** NET Power Inc.
- **CENTRAL INDEX KEY:** 0001845437
- **STANDARD INDUSTRIAL CLASSIFICATION:** ELECTRICAL INDUSTRIAL APPARATUS [3620]
- **ORGANIZATION NAME:** 04 Manufacturing
- **EIN:** 981580612
- **STATE OF INCORPORATION:** NC
- **FISCAL YEAR END:** 1231

**BUSINESS ADDRESS:**
- **STREET 1:** 320 RONEY STREET, SUITE 200
- **CITY:** DURHAM
- **STATE:** NC
- **ZIP:** 27701
- **BUSINESS PHONE:** (919) 287-4750

**MAIL ADDRESS:**
- **STREET 1:** 320 RONEY STREET, SUITE 200
- **CITY:** DURHAM
- **STATE:** NC
- **ZIP:** 27701

**FORMER COMPANY:**
- **FORMER CONFORMED NAME:** Rice Acquisition Corp. II
- **DATE OF NAME CHANGE:** 20210210

### UNITED STATES SECURITIES AND EXCHANGE COMMISSION
**Washington, D.C. 20549**

## FORM 3

### INITIAL STATEMENT OF BENEFICIAL OWNERSHIP OF SECURITIES

[ ] Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

---

| | | |
|:---|:---|:---|
| **1. Name and Address of Reporting Person**<sup>*</sup><br>Horstman Marc<br><sub>(Last) (First) (Middle)</sub><br>320 RONEY STREET<br>SUITE 200<br><sub>(Street)</sub><br>DURHAM, NC 27701<br><sub>(City) (State) (Zip)</sub> | **3. Issuer Name and Ticker or Trading Symbol**<br>NET Power Inc. [ NPWR ] | **5. If Amendment, Date of Original Filed (Month/Day/Year)**<br>  |
| **2. Date of Event Requiring Statement (Month/Day/Year)**<br>2025-04-15 | **4. Relationship of Reporting Person(s) to Issuer**<br>(Check all applicable)<br>[ ] Director   [ ] 10% Owner<br>[X] Officer (give title below)   [ ] Other (specify below)<br>_Chief Operating Officer_ | **6. Individual or Joint/Group Filing (Check Applicable Line)**<br>[X] Form filed by One Reporting Person<br>[ ] Form filed by More than One Reporting Person |

---

## Table I - Non-Derivative Securities Beneficially Owned

---

|  |  |  |  |
| --- | --- | --- | --- |
| 1. Title of Security | 2. Amount of Securities Beneficially Owned | 3. Ownership Form | 4. Nature of Indirect Beneficial Ownership |
| Restricted Stock Units | 165814<sup>(1)</sup> | D |  |
| Class A Common Stock | 1845 | D |  |

---

## Table II - Derivative Securities Beneficially Owned

---

|  |  |  |  |  |  |  |  |
| --- | --- | --- | --- | --- | --- | --- | --- |
| 1. Title of Derivative Security | 2. Date Exercisable and Expiration Date (Month/Day/Year) | 2. Date Exercisable and Expiration Date (Month/Day/Year) | 3. Title and Amount of Underlying Securities | 3. Title and Amount of Underlying Securities | 4. Conversion or Exercise Price | 5. Ownership Form | 6. Nature of Indirect Beneficial Ownership |
| 1. Title of Derivative Security | Date Exercisable | Expiration Date | Title | Amount or Number of Shares | 4. Conversion or Exercise Price | 5. Ownership Form | 6. Nature of Indirect Beneficial Ownership |
|  |  |  |  |  |  |  |  |

---

### Footnotes:

(1) On August 28, 2023, the Reporting Person recieved a grant of 20,000 restricted stock units ("RSUs") that vest on August 28, 2026, subject to continued employment.  On April 2, 2024, the Reporting Person received a grant of 8,442 RSUs, of which 5,527 RSUs are still outstanding and will vest in equal installments on each of April 2, 2026 and April 2, 2027, subject to continued employment.  On April 2, 2025, the Reporting Person received a grant of 46,729 RSUs that will vest in equal installments on each of April 2, 2026, April 2, 2027 and April 2, 2028, subejct to continued employment. On April 2, 2025, the Reporting Person also received a grant of 93,458 RSUs that will vest on April 2, 2028, subject to continued employment.

**Signature:** /s/ Marc Horstman  
**Date:** 2025-06-03

### Remarks:

Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.

* If the form is filed by more than one reporting person, see Instruction 4 (b)(v).

** Intentional misstatements or omissions of facts constitute Federal Criminal Violations See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).

Note: File three copies of this Form, one of which must be manually signed. If space is insufficient, see Instruction 6 for procedure.

**Persons who respond to the collection of information contained in this form are not required to respond unless the form displays a currently valid OMB Number.**