Basis of Presentation - The accompanying unaudited consolidated financial statements are prepared in conformity with accounting principles generally accepted in the United States of America ("US GAAP") and include some amounts that are based upon management estimates and judgments. In the Company's opinion, the accompanying unaudited consolidated financial statements contain all adjustments necessary to present fairly the Company's financial position, results of operations and cash flows for the periods presented. Such adjustments consist solely of normal, recurring adjustments.

Recently Issued Accounting Standards - During October, 2023, the Financial Accounting Standards Board issued Accounting Standards Update ("ASU") 2023-06 - Disclosure Improvements: Codification Amendments in Response to the SEC's Disclosure Update and Simplification Initiative ("ASU 2023-06"). ASU 2023-06 incorporates 14 of the 27 disclosure requirements published in SEC Release No. 33-10532 - Disclosure Update and Simplification into various topics within the Accounting Standards Codification ("ASC"). ASU 2023-06's amendments represent clarifications to, or technical corrections of, current requirements. For SEC registrants, the effective date for each amendment will be the date on which the SEC removes that related disclosure from its rules. Early adoption is prohibited. The Company does not expect ASU 2023-06 to have a material effect on its financial statements.

Principles of Consolidation – The Consolidated Balance Sheets and Consolidated Statements of Operations and Comprehensive Loss include the accounts of subsidiaries that NET Power Inc. consolidates according to the rules set forth in ASC Topic 810 – Consolidation (“ASC 810”). The Company consolidates all subsidiaries in which it owns a 50.0% or greater ownership interest and all variable interest entities ("VIE's") to which it is deemed to represent the primary beneficiary, as described below. The Consolidated Balance Sheets and the Consolidated Statement of Operations and Comprehensive Loss include the accounts of the following wholly-owned subsidiaries and consolidated VIE's: NET Power Europe LTD (“NP Europe”); NET Power Friendship 7, LLC; NET Power Technology, LLC; NET Power Atlas, LLC; NET Power Canaveral, LLC; NET Power Services, LLC, NET Power Management Holdings Inc.; NET Power Management LLC; NET Power Operations LLC ("OpCo"); NET Power Intermediate LLC and NET Power, LLC. Intercompany balances have been eliminated through the consolidation process.

ASC 810 requires that a reporting entity that possesses a controlling financial interest in a VIE consolidate that VIE. A controlling financial interest will have both of the following characteristics: (a) the power to direct the activities that most significantly impact the VIE's economic performance; and (b) the obligation to absorb the VIE's losses and the right to receive benefits that are significant to the VIE. The Company determined that NET Power Operations LLC meets the definition of a VIE and that the Company became the primary beneficiary of it beginning on the Closing Date of the

Business Combination – The Company applies the guidance within ASC Topic 805 – Business Combinations ("ASC 805") to all merger and acquisition transactions, including the Business Combination (Note C), through which the Company obtains control over one or more other businesses.

The Company may elect the acquisition method for all transactions and other events through which the Company obtains control over one or more other businesses, including the Business Combination (Note C). Under the acquisition method, assets acquired and liabilities assumed are measured at fair value as of the acquisition date. Liabilities related to contingent consideration are recognized on the acquisition date and re-measured at fair value in each subsequent reporting period, if the contingent consideration is liability classified. Goodwill is recognized as the excess of the consideration transferred over the fair value of the net identifiable assets acquired.

Revenue Recognition, Trade Receivables and Allowance for Doubtful Accounts – The Company follows the guidance within ASC Topic 606 – Revenue from Contracts with Customers to determine how and when it recognizes revenues. The Company accounts for a customer contract when both parties have approved the contract and are committed to perform their respective contractual obligations, each party’s rights can be identified, payment terms can be identified, the contract has commercial substance and it is probable that the Company will collect the consideration to which it is entitled.

When billed in advance, the payment is deferred and recognized upon delivery of the service. Collectability is assessed based on a number of factors including collection history and customer creditworthiness. If collectability of substantially all consideration to which the Company is entitled under the contract is determined to be not probable, revenue is not recorded until collectability becomes probable. Revenue is recorded based on the transaction price excluding amounts collected on behalf of third parties, such as sales taxes collected and remitted to governmental authorities.

Trade receivables are recorded at the invoiced amount and do not bear interest. The Company calculates an allowance for doubtful accounts based on a risk assessment performed when trade receivables are recognized. The allowance is calculated in accordance with ASC Topic 326 - Current Expected Credit Losses. Write-offs are recorded at the time when trade receivables are deemed uncollectible.

The Company has historically recognized revenue from two primary sources, feasibility studies and government grants. Feasibility studies represent reports prepared to assist a customer in determining the viability of the NET Power Cycle for their specific use case. Government grants represent U.S. federal programs that incentivize the development of novel energy solutions. The Company has served as a sub-recipient to such government grants. Feasibility studies generally contain one performance obligation, the customer’s acceptance of the feasibility study report at the end of the review period. Government grants generally contain multiple performance obligations related to the incursion of costs associated with the development of in-scope activities that entitle the Company, as sub-recipient, to reimbursement from the primary grant recipient.

Fair Value - Certain assets and liabilities are carried at fair value in accordance with ASC Topic 820 – Fair Value Measurement. Fair value is defined as the price that would be received for an asset or paid to transfer a liability (i.e., the exit price) in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. The guidance establishes a fair value hierarchy that prioritizes the inputs used to measure fair value. The hierarchy gives the highest priority to unadjusted quoted prices in active markets for identical assets or liabilities (Level 1 measurements) and the lowest priority to unobservable inputs (Level 3 measurements). The three levels of the fair value hierarchy are as follows:

•Level 2 - Significant other observable inputs other than Level 1 prices, such as quoted prices for similar, but not identical, assets or liabilities in active markets; quoted prices for identical or similar assets or liabilities in markets that are not active; or other inputs that are observable or can be corroborated by observable market data; and

be reasonable, but which are uncertain and involve significant managerial judgments made by considering factors specific to the asset or liability. The determination of fair value requires more judgment to the extent the valuation is based on models or inputs that are less observable or unobservable in the market. Accordingly, the degree of judgment exercised by the Company in determining the fair value is greatest for instruments categorized as Level 3.

Cash - Cash consists of liquid deposits at banking institutions that are members of the Federal Deposit Insurance Corporation (“FDIC”) and the Financial Services Compensation Scheme (“FSCS”), the UK’s statutory compensation system for customers of authorized financial services firms. FDIC guidelines guarantee $250 per depositor, per insured bank and FSCS guidelines guarantee £85 per depositor per insured bank. As of September 30, 2023 (Successor) and December 31, 2022 (Predecessor), the Company possessed funds in excess of FDIC limits equal to $544,727 and $4,644 respectively. The carrying value of cash equals its fair value.

Warrants - The Company issued Public Warrants and Private Placement Warrants prior to the consummation of the Business Combination (Note C). The Company accounts for both the Public Warrants and Private Placement Warrants as liability-classified instruments based on an assessment of the Warrants’ specific terms and applicable authoritative guidance outlined in ASC Topic 480 - Distinguishing Liabilities from Equity ("ASC 480"), ASC Topic 815 - Derivatives and Hedging ("ASC 815") and relevant SEC reporting rules. The guidance considers whether the Warrants are freestanding financial instruments pursuant to ASC 480, whether the Warrants meet the definition of a liability pursuant to ASC 480, whether the Warrants meet all of the requirements for equity classification under ASC 815 and whether class of equity into which the Warrants settle possess substantive voting rights. This assessment is conducted at the time of the instruments’ issuance and at each subsequent quarterly period end date while the Warrants remain outstanding. In compliance with ASC 815, the Company accounts for the outstanding Warrants as a liability at fair value on the Consolidated Balance Sheets. The Warrants are subject to remeasurement at each Balance Sheets date with any change in the Warrants’ fair value recognized in the Company’s Consolidated Statements of Operations and Comprehensive Loss.

Short-Term Investments - The Company classifies investments with maturities greater than three months but less than one year as short-term investments. As of September 30, 2023, the Company's short-term investment balance consisted of a single six-month certificate of deposit custodied by a domestic banking institution.

Short-term investments are classified as held-to-maturity according to the guidance contained within ASC 326 - Financial Instruments - Credit Losses because the Company has the intent and ability to hold the certificate of deposit until maturity. Interest income generated from short-term investments is recorded as interest income in the Company's Consolidated Statements of Operations and Comprehensive Loss.

Tax Receivable Agreement Liability - As part of the Business Combinations (Note C), the Company entered into the TRA with certain OpCo unitholders that will represent approximately 75% of the calculated tax savings based on the portion of basis adjustments on exchanges of OpCo units and other carryforward attributes that are anticipated to be able to be utilized in future years. Such tax attributes include the existing tax basis of certain assets of OpCo and its consolidated subsidiaries; tax basis adjustments resulting from taxable exchanges of Class A OpCo Units; certain tax benefits realized by NET Power Inc. as a result of the Business Combination and tax deduction in respect of portions of certain TRA payments. All such payments made under the terms of the TRA are the obligations of NET Power Inc. and not of OpCo.

Intangible Assets - The Company accounts for intangible assets, which consist of developed technology related to the NET Power Cycle, in accordance with ASC Topic 350 - Goodwill and Other Intangible Assets (“ASC 350”). The following table summarizes the estimated useful lives used to amortize definite lived intangible assets:

Property, Plant and Equipment - Property, plant and equipment are recorded at the historical cost to acquire the assets. The costs bases of property, plant and equipment to which the Company held title prior to the Business Combination completion (Note C) were stepped-up to their respective fair values on June 8, 2023 in accordance with the closure of the Business Combination. The Demonstration Plant's depreciable value consists of costs associated with the engineering, procurement, and construction of the facility.

Depreciation is calculated on the straight-line method over the estimated useful lives of the assets. Amounts capitalized to construction in progress are not depreciated until the underlying asset is placed into service. The following table summarizes the estimated useful lives used to depreciate property, plant and equipment and assets:

Impairment of Definite-Lived Assets - In accordance with ASC Topic 360 - Property, Plant and Equipment, tangible and intangible assets with finite useful lives are evaluated for impairment whenever events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable. Recoverability of assets placed in service is measured by comparing the carrying amount of an asset or asset group to the future undiscounted cash flows expected to be generated by the asset or asset group. If such assets are considered to be impaired, impairment equals the amount by which the carrying amount of the assets exceeds the fair value of the assets. There were no impairment charges recorded during the June 8 through September 30, 2023 (Successor) period or during the year ended December 31, 2022 (Predecessor).

Lease Agreements – Lease agreements may fall within two categories according to ASC Topic 842 – Leases ("ASC 842"), operating leases or financing leases. Both operating and finance leases result in the recognition of lease liabilities and associated right-of-use assets that are valued at the net present value of the lease payments and recognized. The Company has elected the short-term lease exception and therefore only recognizes right-of-use assets and lease liabilities for leases with a term greater than one year. The lease term includes the committed lease term identified in the contract, taking into account renewal and termination options that management is reasonably certain to exercise. The discount rate used in the measurement of a right-to-use asset and lease liability is the rate implicit in the lease whenever that rate is readily determinable. If the rate implicit in the lease is not readily determinable, the Company uses its incremental borrowing rate as a proxy for the discount rate based on the term of the lease unless the implicit rate is available.

Asset Retirement Obligation – The Company recognizes liabilities and the corresponding assets for future obligations associated with the retirement of assets. The fair values of legal obligations to retire and remove long-lived assets are recorded in the period in which the obligation is incurred. Prior to the consummation of the Business Combination (Note C), asset retirement obligations were reflected in property, plant and equipment. In conjunction with the Business Combination, the Company re-measured its property, plant and equipment assets at their respective June 8, 2023 fair values, which resulted in the asset retirement obligation being removed from Property, plant and equipment on the Consolidated Balance Sheets. When an asset retirement obligation arises, the liabilities and corresponding assets are recorded at their present values using a discounted cash flow approach and the liabilities are accreted using the interest method. The asset retirement costs and corresponding liabilities that have been recorded to-date relate to the obligations of the land lease for the property underneath the Demonstration Plant at the end of the Demonstration Plant's estimated useful life.

The Company’s valuation of the asset retirement obligation related to the Demonstration Plant encompasses an estimate for the cost to restore the site as required by lease terms. The accretion expense generated by the Company’s asset retirement obligation liability is recognized ratably over the Demonstration Plant’s expected seven year useful life.

Net Loss per Unit - During the Predecessor Period, the Company computed basic net loss per unit by dividing the total net loss applicable to membership interest holders by the weighted average number of membership interests outstanding during the period. The Company computed diluted net loss per unit by dividing the net loss applicable to membership interest holders by the sum of the weighted-average number of membership interests outstanding during the period and the

potentially dilutive effects of distribution units, profits interests and options to purchase membership interests. Such items were excluded if their effect was anti-dilutive. Since the impact of the distribution units, profits interests, and options to purchase membership interests were anti-dilutive during periods of net loss, there was no difference between the Company’s basic and diluted net loss per unit for the period from January 1, 2023 through June 7, 2023 (Predecessor) or the year ended December 31, 2022 (Predecessor).

Net Loss per Share - During the Successor Period, basic net loss per share is computed based on the weighted average number of shares of Class A Common Stock outstanding. Diluted net loss per share is computed based on the weighted average number of common shares outstanding, increased by the number of any additional shares that would have been outstanding had any potentially dilutive common shares been issued. For the purposes of the diluted earnings per share calculation, Warrants, Earnout Shares, restricted stock units and conversion of OpCo Units are excluded from the calculation for the period from June 8 through September 30, 2023 (Successor), as the inclusion would be anti-dilutive due to the losses reported in the year.

Equity Based Compensation – The Company applies ASC Topic 718 – Share-Based Payments (“ASC 718”) to account for its equity awards. Equity awards granted to employees include unvested Class A OpCo Units and a corresponding number of unvested shares of Class B Common Stock and RSU's that settle into shares of Class A Common Stock upon vesting. Generally, each award is subject to a service condition that requires a specific period of continued employment or service to the Company to elapse before the award fully vests. Certain awards also include performance conditions to vest fully. The Board’s Compensation Committee establishes these service and performance conditions.

The estimated fair value of NET Power, LLC membership units was determined by an independent, external valuation service provider at each equity grant date until the the Closing Date, upon which the Company became publicly traded. On the Closing Date, the Company fair valued the OpCo Units used to satisfy outstanding share-based awards at the fair value of the Company's Class A Common Stock.

In accordance with ASC 718, the Company recognizes expense related to equity awards for which vesting is considered probable. Forfeitures are recognized as they occur. For service-based awards, compensation cost is measured at fair value on the grant date and expensed ratably over the vesting term. For performance-based grants, the fair value is measured on the grant date and recognized as non-cash compensation expense, considering the probability of the targets being achieved. The Company recognizes compensation expense generated by all service-based awards on a straight-line basis over the underlying awards's vesting period.

Earnout Shares and Restricted Shares - As part of the Business Combination (Note C), 128,908,518 Class A OpCo Units and a corresponding number of shares of Class B Common Stock, 7,624,999 Class B OpCo Units and a corresponding number of shares of Class B Common Stock and 54,047,495 shares of Class A Common Stock owned by the Sponsor, the Sponsor's affiliates and private investors were subjected to certain vesting and transfer restrictions. Upon conversion of Class B OpCo Units to Class A OpCo Units (Note K), the 6,072,463 Class B OpCo Units subject to vesting and transfer restrictions became Class A OpCo Units.

Of the total shares subject to vesting and transfer restrictions, 986,775 Class A OpCo Units, all of which were formerly Class B OpCo Units, and a corresponding number of shares of Class B Common Stock vest in three equal tranches contingent upon the share price of the Class A Common Stock (the "Earnout Shares"). The first tranche vests if the closing price of the Class A Common Stock on the NYSE is greater than or equal to $12.00 for any 20 trading days within a consecutive 30-trading-day period beginning on or after June 23, 2023. The second tranche vests if the closing price of the Class A Common Stock on the NYSE is greater than or equal to $14.00 for any 20 trading days within a consecutive 30-trading-day period beginning on or after June 23, 2023. The third tranche vests if the closing price of the Class A Common Stock on the NYSE is greater than or equal to $16.00 for any 20 trading days within a consecutive 30-trading-day period beginning on or after June 23, 2023 and ending on the three-year anniversary of the Closing Date.

Of the OpCo Units subject to transfer restrictions, 44,544,551 Class A OpCo Units, of which 1,575,045 were formerly Class B OpCo Units, (the “Price-Based Lock-up Shares”) may not be transferred until after the three-year anniversary of the Closing Date; provided, however, that if the last sale price of the Class A Common Stock on the NYSE, for any 20 trading days within any 30 consecutive trading-day period commencing on or after June 23, 2023 exceeds (or, in the case of the 1,575,045 Class A OpCo Units that were formerly Class B OpCo Units, equals) (i) $12.00 per share, then one-third of the Price-Based Lock-up Shares will no longer be subject to such lock-up restrictions, (ii) $14.00 per share, then an additional one-third of the Price-Based Lock-up Shares will no longer be subject to such lock-up restrictions, and (iii) $16.00 per share, then all of the Price-Based Lock-up Shares will no longer be subject to such lock-up restrictions.

The remaining 89,449,655 Class A OpCo Units, of which 3,510,643 were formerly Class B OpCo Units (the “Time-Based Lock-up Shares”) subject to transfer restrictions may not be transferred until after the one-year anniversary of the Closing Date; provided, however, that if the last sale price of the Class A Common Stock on the NYSE, for any 20 trading days within any 30 consecutive trading-day period commencing on or after December 8, 2023, exceeds (or in the case of the 3,510,643 Class A OpCo Units that were formerly Class B OpCo Units, equals) $12.00 per share, then the Time-Based Lock-up Shares will no longer be subject to such lock-up restrictions.

Unvested Earnout Shares are reported as liabilities within the Company’s Consolidated Balance Sheets. The liability classification reflects the Company’s evaluation of the Earnout Shares according to ASC 480’s and ASC 815’s standards. The Price Based Lockup Shares and the Time-Based Lockup Shares are included as equity within the Company's Consolidated Balance Sheets.

Non-Controlling Interest - Non-controlling interests (“NCI”) represent Legacy NET Power Holders partners’, sponsors' and certain strategic partners' respective ownership of OpCo. After the conversion of Class B OpCo Units to Class A OpCo Units, NCI is comprised exclusively of Class A OpCo Units (Note K). After evaluating Class A OpCo Unit redemption rights under ASC 480, the Company determined that Class A OpCo Units are subject to potential cash redemption that rests outside the Company's control. The Company has classified NCI as a component of mezzanine equity in consideration of this cash redemption feature and in accordance with ASC 810's guidance.

After considering the effects of consolidation, the Company owns 32.6% of OpCo and NCI holders own the residual 67.4%. The Company's net loss before income tax and its comprehensive loss in the Successor Period are reduced by the portions of net loss before income tax and comprehensive loss, respectively, that are attributable to non-controlling interests.

Research and Development Costs - The Company expenses costs related to operations and testing at the Demonstration Plant, as well as engineering and design costs related to development of the NET Power Cycle as incurred. These costs are included in Research and Development on the Consolidated Statements of Operations and Comprehensive Loss.

The Company has entered into contractual relationships with several of its current shareholders and former members that qualify as related parties according to the aforementioned criteria. These relationships include loans from members and master service agreements (“MSA's”).

Income and Uncertain Taxes – The Company applies the guidance set forth in ASC Topic 740 – Income Taxes (“ASC 740”) to evaluate its tax positions. The Company evaluates the realizability of deferred tax assets on a quarterly basis and establishes a valuation allowance when it is more-likely-than-not that all or a portion of a deferred tax asset may not be realized. The Company calculates the provision for income taxes during interim periods by applying an estimate of the forecasted annual effective tax rate for the full fiscal year to ordinary income or loss (pretax income or loss excluding unusual or infrequently occurring discrete items) for the reporting period.

NET Power Inc. consolidates the financial results of OpCo in its consolidated financial statements. OpCo represents a pass-through entity for U.S. federal and most applicable state and local income tax purposes. As a pass-through entity for tax purposes, OpCo is not subject to U.S. federal and certain state and local income taxes. Any taxable income or loss generated by OpCo is passed through to its members, including NET Power Inc., which is taxed as a corporation that pays corporate federal, state and local taxes with respect to income allocated from OpCo based on its economic interest in OpCo.

NP Europe is subject to taxation pursuant to UK tax regulations. For the quarter ended September 30, 2023 (Successor) and the year ended December 31, 2022 (Predecessor), NP Europe incurred taxable losses, which may be used to offset future profits. The Company has established a valuation allowance against possible future tax benefits because the ability to recognize these benefits does not meet ASC 740's more-likely-than-not recognition threshold; therefore, no provision or asset for UK income taxes has been included in the consolidated financial statements.