[Congressional Bills 118th Congress]
[From the U.S. Government Publishing Office]
[S. 4144 Introduced in Senate (IS)]

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118th CONGRESS
  2d Session
                                S. 4144

  To improve the reliability and adequacy of the bulk-power system by 
  ensuring that key uncertainties in generation, transmission, energy 
storage systems, and loads are considered in resource adequacy modeling 
       and integrated resource planning, and for other purposes.


_______________________________________________________________________


                   IN THE SENATE OF THE UNITED STATES

                             April 17, 2024

 Mr. Heinrich (for himself, Mr. Wyden, and Mr. Padilla) introduced the 
 following bill; which was read twice and referred to the Committee on 
                      Energy and Natural Resources

_______________________________________________________________________

                                 A BILL


 
  To improve the reliability and adequacy of the bulk-power system by 
  ensuring that key uncertainties in generation, transmission, energy 
storage systems, and loads are considered in resource adequacy modeling 
       and integrated resource planning, and for other purposes.

    Be it enacted by the Senate and House of Representatives of the 
United States of America in Congress assembled,

SECTION 1. SHORT TITLE.

    This Act may be cited as the ``Grid Modeling of Dynamic Energy 
Loads and Resources Act of 2024'' or the ``Grid MODEL Act of 2024''.

SEC. 2. DEFINITIONS.

    In this Act:
            (1) Bulk-power system.--The term ``bulk-power system'' has 
        the meaning given the term in section 215(a) of the Federal 
        Power Act (16 U.S.C. 824o(a)).
            (2) Commission.--The term ``Commission'' means the Federal 
        Energy Regulatory Commission.
            (3) Effective load carrying capability; elcc.--
                    (A) In general.--The term ``effective load carrying 
                capability'' or ``ELCC'' means the ability of a 
                generating resource to produce electricity when the 
                grid needs it, measured as the additional load (or 
                perfect replacement capacity) that the system can 
                supply with a particular generator of interest with no 
                net change in reliability.
                    (B) Clarification.--The additional load (or perfect 
                replacement capacity) referred to in subparagraph (A)--
                            (i) may be measured using LOLE, EUE, or 
                        other metrics; and
                            (ii) may be divided by the nameplate 
                        capacity of the generating resource to yield a 
                        percentage.
            (4) Electric reliability organization.--The term ``Electric 
        Reliability Organization'' has the meaning given the term in 
        section 215(a) of the Federal Power Act (16 U.S.C. 824o(a)).
            (5) Electric utility.--The term ``electric utility'' has 
        the meaning given the term in section 3 of the Federal Power 
        Act (16 U.S.C. 796).
            (6) Expected unserved energy; eue.--The term ``expected 
        unserved energy'' or ``EUE'' means the cumulative amount of 
        energy (in megawatt-hours) per year that is not provided to 
        customers due to outages.
            (7) Independent system operator.--The term ``Independent 
        System Operator'' has the meaning given the term in section 3 
        of the Federal Power Act (16 U.S.C. 796).
            (8) Integrated resource planning.--The term ``integrated 
        resource planning'' means modeling and evaluating how projected 
        long-term electricity demands (such as electricity demands over 
        periods of 5, 10, 20, or more years) within a service area can 
        be met with a combination of electric generation resources that 
        best achieve desired metrics, such as metrics relating to 
        reliability, resilience, and cost.
            (9) Loss of load expectation; lole.--
                    (A) In general.--The term ``loss of load 
                expectation'' or ``LOLE'' means the expected number of 
                days per year that the available generation capacity is 
                less than the system load for the applicable power grid 
                region or service area.
                    (B) Clarification.--As of November 2023, a commonly 
                acceptable value for loss of load expectation is 0.1 
                days per year, as described in the standard of the 
                North American Electric Reliability Corporation 
                entitled ``Planning Resource Adequacy Analysis, 
                Assessment and Documentation'' and numbered BAL-502-RF-
                03.
            (10) Planning reserve margin.--
                    (A) In general.--The term ``planning reserve 
                margin'' means the quotient, expressed as a percentage, 
                obtained by dividing--
                            (i) the difference between--
                                    (I) deliverable electric system 
                                supply capacity for a power grid region 
                                or service area; and
                                    (II) net demand in that power grid 
                                region or service area; by
                            (ii) net demand in that power grid region 
                        or service area.
                    (B) Clarification.--As of November 2023, a reserve 
                margin falling within the range from 15 percent to 25 
                percent is typical for a power grid region or service 
                area.
            (11) Power grid.--The term ``power grid'' means that 
        portion of an Interconnection (as defined in section 215(a) of 
        the Federal Power Act (16 U.S.C. 824o(a))) that is located 
        within the United States, including the relevant portion of 
        each of the following:
                    (A) The Eastern Interconnection.
                    (B) The Western Interconnection.
                    (C) The Texas Interconnection.
            (12) Power grid region.--The term ``power grid region'' 
        means a geographic area--
                    (A) located within a power grid; and
                    (B) for which a regional entity (as defined in 
                subsection (a) of section 215 of the Federal Power Act 
                (16 U.S.C. 824o)) has enforcement authority under that 
                section.
            (13) Probabilistic modeling.--
                    (A) In general.--The term ``probabilistic 
                modeling'' means a modeling approach that uses 
                statistics to simulate and quantify the likelihood of 
                achieving desired metrics, taking into consideration 
                all modeled uncertainties, for determination of the 
                optimal resource portfolio, such as a modeling approach 
                consistent with the document of the North American 
                Electric Reliability Corporation entitled 
                ``Probabilistic Assessment Technical Guideline 
                Document'' and dated August 2016, including the 
                recommendations described in that document.
                    (B) Inclusion.--The term ``probabilistic modeling'' 
                includes modeling that can identify the most important 
                parameters that impact a simulated metric for further 
                characterization or optimization.
            (14) Regional transmission organization.--The term 
        ``Regional Transmission Organization'' has the meaning given 
        the term in section 3 of the Federal Power Act (16 U.S.C. 796).
            (15) Reliability standard.--The term ``reliability 
        standard'' has the meaning given the term in section 215(a) of 
        the Federal Power Act (16 U.S.C. 824o(a)).
            (16) Resource adequacy.--The term ``resource adequacy'' 
        means the adequate supply and provision of electricity from 
        various electric generation resources to meet projected 
        electricity demands in a particular power grid region or 
        service area.
            (17) Service area.--The term ``service area'' means the 
        area or region served by--
                    (A) an electric utility;
                    (B) a Regional Transmission Organization; or
                    (C) an Independent System Operator.
            (18) State regulatory authority.--The term ``State 
        regulatory authority'' has the meaning given the term in 
        section 3 of the Federal Power Act (16 U.S.C. 796).

SEC. 3. PROBABILISTIC MODELING FOR BULK-POWER SYSTEM RESOURCE ADEQUACY 
              MODELING AND INTEGRATED RESOURCE PLANNING.

    (a) In General.--The Commission, pursuant to section 215(d) of the 
Federal Power Act (16 U.S.C. 824o(d)), shall--
            (1) as soon as practicable after the date of enactment of 
        this Act, order the Electric Reliability Organization to submit 
        to the Commission, not later than 18 months after the date of 
        that order, or as soon as practicable thereafter, 1 or more 
        proposed reliability standards or modifications to reliability 
        standards to require, and ensure consistent methods (based on 
        best-practices) for, the use of probabilistic modeling that 
        includes consideration of key uncertainties in generation, 
        transmission, energy storage systems, and loads for resource 
        adequacy modeling and integrated resource planning relating to 
        the bulk-power system, reflecting the specific needs, 
        resources, and attributes of a given power grid region or 
        service area; and
            (2) as soon as practicable after the submission of a 
        proposed reliability standard or modification of a reliability 
        standard under paragraph (1), approve the proposed reliability 
        standard or modification in accordance with that section, if 
        appropriate.
    (b) Requirements.--
            (1) Generation.--With respect to generation, the 
        reliability standards approved under subsection (a) shall 
        require that probabilistic modeling for resource adequacy 
        modeling and integrated resource planning shall include, to the 
        maximum extent practicable, consideration of uncertainties 
        relating to, as applicable for a given power grid region or 
        service area--
                    (A) the impact of distributed generation resources;
                    (B) degradation from aging (such as soiling and 
                degradation of photovoltaic modules and batteries);
                    (C) planned and unplanned outages;
                    (D) the impact of weather (such as solar 
                irradiance, wind, precipitation, snowpack, and extreme 
                temperatures) on conventional and distributed 
                generation resources;
                    (E) correlated outages (such as correlated outages 
                due to winter storms, extreme heat, wildfires, and 
                other extreme weather events);
                    (F) costs of generation resources, including costs 
                of acquired energy efficiency as a resource; and
                    (G) other relevant generation uncertainties, as 
                determined by the relevant electric utility, Regional 
                Transmission Organization, Independent System Operator, 
                or State regulatory authority.
            (2) Transmission.--With respect to transmission, the 
        reliability standards approved under subsection (a) shall 
        require that probabilistic modeling for resource adequacy 
        modeling and integrated resource planning shall include, to the 
        maximum extent practicable, consideration of uncertainties 
        relating to, as applicable for a given power grid region or 
        service area--
                    (A) the impact of weather (such as the impact of 
                temperature on transmission facilities, including line 
                ratings);
                    (B) congestion and thermal overload;
                    (C) costs of new or modified transmission 
                infrastructure; and
                    (D) other relevant transmission uncertainties, as 
                determined by the relevant electric utility, Regional 
                Transmission Organization, Independent System Operator, 
                or State regulatory authority.
            (3) Energy storage.--With respect to energy storage, the 
        reliability standards approved under subsection (a) shall 
        require that probabilistic modeling for resource adequacy 
        modeling and integrated resource planning shall include, to the 
        maximum extent practicable, consideration of uncertainties 
        relating to, as applicable for a given power grid region or 
        service area--
                    (A) round-trip efficiency;
                    (B) battery capacity fade;
                    (C) the impact of weather (such as the impact of 
                drought on pumped hydrologic storage);
                    (D) the impact of distributed energy storage;
                    (E) costs of energy storage; and
                    (F) other relevant energy storage uncertainties, as 
                determined by the relevant electric utility, Regional 
                Transmission Organization, Independent System Operator, 
                or State regulatory authority.
            (4) Loads.--With respect to loads, the reliability 
        standards approved under subsection (a) shall require that 
        probabilistic modeling for resource adequacy modeling and 
        integrated resource planning shall include, to the maximum 
        extent practicable, consideration of uncertainties relating to, 
        as applicable for a given power grid region or service area--
                    (A) the impact of temperature and weather, 
                including extreme weather events, on loads;
                    (B) the timing and changing mix of loads, 
                including--
                            (i) increased electrification of 
                        transportation, including bidirectional 
                        charging and discharging of batteries used in 
                        electric vehicles;
                            (ii) increased electrification of home 
                        appliances, such as hot-water heaters and 
                        ovens, and space heating and cooling; and
                            (iii) increased electrification of 
                        industrial processes; and
                    (C) other relevant electric-load uncertainties, as 
                determined by the relevant electric utility, Regional 
                Transmission Organization, Independent System Operator, 
                or State regulatory authority.
    (c) Use of Modeling.--The reliability standards approved under 
subsection (a) shall require probabilistic modeling to be used, at a 
minimum--
            (1) to simulate and quantify desired metrics (such as loss 
        of load expectation, expected unserved energy, effective load 
        carrying capability (also known as ``capacity value''), 
        planning reserve margin, and cost), taking into consideration 
        the relevant uncertainties described in subsection (b), to 
        assist in the determination of the optimal resource portfolio 
        for the applicable power grid region or service area; and
            (2) to identify the parameters and processes considered 
        under subsection (b) that--
                    (A) are the most important, in that they have the 
                most impact on the magnitude or uncertainty of the 
                applicable simulated metrics; and
                    (B) can be further characterized or optimized to 
                improve the modeling and determination of the optimal 
                resource portfolio for the applicable power grid region 
                or service area.
    (d) Existing Approaches; State Requirements.--
            (1) In general.--The reliability standards approved under 
        subsection (a)--
                    (A) shall take into consideration, and shall allow 
                for the continued use of, any probabilistic modeling in 
                use by an electric utility, a Regional Transmission 
                Organization, or an Independent System Operator as of 
                the date of enactment of this Act; and
                    (B) shall not preempt, or exempt any electric 
                utility, Regional Transmission Organization, or 
                Independent System Operator from compliance with, any 
                probabilistic modeling requirement under State law.
            (2) Requirements.--To the maximum extent practicable, the 
        reliability standards approved under subsection (a) shall allow 
        for compliance with those reliability standards to be 
        achieved--
                    (A) in a manner consistent with--
                            (i) the probabilistic modeling described in 
                        subparagraph (A) of paragraph (1); and
                            (ii) any requirements described in 
                        subparagraph (B) of that paragraph; and
                    (B) by demonstrating--
                            (i) the use of probabilistic modeling in 
                        accordance with subparagraph (A) or (B) of that 
                        paragraph; and
                            (ii) that the probabilistic modeling 
                        adequately reflects, or has been modified or 
                        used in a manner to adequately reflect, the 
                        requirements described in subsections (b) and 
                        (c).
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