Parallel Computing for Two-Stage Stochastic Infrastructure Planning
The authors thank Gurobi for providing licenses to the Gurobi Optimizer, used for this work. The authors also thank the volume editors and four reviewers of this tutorial for their feedback, which helped make this tutorial stronger. Artificial intelligence (AI) has not been used anywhere in the body text presented in this manuscript. AI was used, prompted by the authors, to create the diagrams and the code examples. The products were verified by the authors, who are solely responsible for their correctness.
1 Infrastructure planning problems for electrical power systems are commonly called CEP problems. To avoid confusion, we use “stochastic infrastructure planning problem” (SIPP) to refer to the generic problem and “CEP” only for the case of the electric grid.
2 Throughout this tutorial, we use bold letters to refer to vectors, capital letters to refer to matrices, and script capital letters (as well as for scenarios) to refer to sets.
3 It is also possible to bundle scenarios together so that subproblems correspond to subsets of the uncertainty set, but this is out of scope for this tutorial; see, for example, Ryan et al. [63].
4 The package mpi-sppy requires Python but supports several modeling languages for providing the description of the optimization problem. The example presented in this tutorial was developed using Pyomo, which is required to reproduce the tests (or the reader will need to translate them to the supported language of their choice). We refer the reader to Bynum et al. [9] for guidance using Pyomo.
5 For reproducibility by the reader, note that the examples in this tutorial were developed and tested with Pyomo 6.10.2 and Gurobi 11.0.3. For an open-source solver alternative, HiGHS 1.14 (Huangfu and Hall [37]) was used (results not shown here). A released version of mpi-sppy > 0.13.1 (strictly above) should be used to ensure access to the examples of this tutorial. The relief examples directory in GitHub also includes shell scripts with the command-line instructions of each example presented here.
6 The examples here use the Gurobi solver, which is accessible to many researchers via academic licenses. For an open-source alternative, the reader may want to try HiGHS, CBC (COIN-OR Branch and Cut solver) or GLPK (GNU linear programming kit solver).
References
- [1] . How CBO uses the ReEDS model to analyze policies in the electric power sector. Working Paper 2024-02, Congressional Budget Office, Washington, DC, 2024.Google Scholar
- [2] .
Solving chance-constrained stochastic programs via sampling and integer programming . Z. L. Chen and S. Raghavan, eds. State-of-the-Art Decision-Making Tools in the Information-Intensive Age, INFORMS TutORials in Operations Research. INFORMS, Catonsville, MD, 261–269, 2008.Link, Google Scholar - [3] . A novel partitioning algorithm for constructing diverse solution sets for the unit commitment problem. Proceedings of the 2025 FERC Software Conference. Federal Energy Regulatory Commission, Washington, DC, 2025.Google Scholar
- [4] Regional Energy Deployment System (ReEDS) model documentation: 2025. Technical report NREL/TP-6A40-93617, National Renewable Energy Laboratory, Golden, CO, 2025.Google Scholar
- [5] .
Assessing solution quality in stochastic programs via sampling . M. R. Oskoorouchi, ed. Decision Technologies and Applications, INFORMS TutORials in Operations Research. INFORMS, Catonsville, MD, 102–122, 2009.Link, Google Scholar - [6] . Introduction to Linear Optimization. Athena Scientific, Belmont, MA, 1997.Google Scholar
- [7] . Introduction to Stochastic Programming, Springer Series in Operations Research and Financial Engineering, 2nd edition. Springer, New York, 2011.Crossref, Google Scholar
- [8] . Combining progressive hedging with a Frank–Wolfe method to compute Lagrangian dual bounds in stochastic mixed-integer programming. SIAM Journal on Optimization 28(2):1312–1336, 2018.Crossref, Google Scholar
- [9] . Pyomo–Optimization Modeling in Python, Springer Optimization and Its Applications, volume 67, 3rd edition. Springer, Cham, Switzerland, 2021.Crossref, Google Scholar
- [10]
California Independent System Operator . 2024–2025 transmission planning process: Unified planning assumptions and study plan. Technical report, California Independent System Operator, Folsom, CA, 2024.Google Scholar - [11]
California Public Utilities Commission . Public safety power shutoffs (PSPS). Accessed March 6, 2026, https://www.cpuc.ca.gov/psps/.Google Scholar - [12] . Confidence interval software for multi-stage stochastic programs. Preprint, submitted September 28, https://optimization-online.org/?p=17549, 2021.Google Scholar
- [13] . A graph-based, distributed memory, modeling abstraction for optimization. Preprint, submitted November 18, https://arxiv.org/abs/2511.14966, 2025.Google Scholar
- [14] . Investment in Electricity Generation and Transmission: Decision Making under Uncertainty, 1st edition. Springer, Cham, Switzerland, 2016.Crossref, Google Scholar
- [15] . Decomposition Techniques in Mathematical Programming. Springer-Verlag, Berlin, 2006.Google Scholar
- [16]
Cybersecurity and Infrastructure Security Agency . Critical infrastructure sectors. Accessed March 21, 2026, https://www.cisa.gov/topics/critical-infrastructure-security-and-resilience/critical-infrastructure-sectors.Google Scholar - [17] . The dried-out subdivisions of Phoenix. High Country News (October 6), https://www.hcn.org/issues/57-10/the-dried-out-subdivisions-of-phoenix/, 2025.Google Scholar
- [18] . SDDP.jl: A Julia package for stochastic dual dynamic programming. INFORMS Journal on Computing 33(1):27–33, 2021.Link, Google Scholar
- [19] . Stochastic network optimization for strategic resource pre-positioning and allocation. International Journal of Production Economics 287:109679, 2025. Crossref, Google Scholar
- [20] . Projective hedging algorithms for multistage stochastic programming, supporting distributed and asynchronous implementation. Operations Research 73(1):311–324, 2025.Link, Google Scholar
- [21] . Design of engineering systems using stochastic decomposition: Water supply planning application. Engineering Optimization 27(4):279–302, 1997.Crossref, Google Scholar
- [22] . A stochastic programming model for water resource planning. Mathematical and Computer Modelling 27(3):1–7, 1998.Crossref, Google Scholar
- [23] . A distributed computing framework for multi-stage stochastic planning of renewable power systems with energy storage as flexibility option. Applied Energy 291:116736, 2021. Crossref, Google Scholar
- [24] . A comprehensive review on expansion planning: Models and tools for energy policy analysis. Renewable and Sustainable Energy Reviews 98:346–360, 2018.Crossref, Google Scholar
- [25] .
Stochastic optimization problems in telecommunications . S. W. Wallace and W. T. Ziemba, eds. Applications of Stochastic Programming, MOS-SIAM Series on Optimization. Society for Industrial and Applied Mathematics, Philadelphia, 669–704. 2005.Crossref, Google Scholar - [26] .
Stochastic optimization in telecommunications . M. G. C. Resende and P. M. Pardalos, eds. Handbook of Optimization in Telecommunications. Springer, Boston, 761–799, 2006.Crossref, Google Scholar - [27] . Electricity grid capacity expansion planning considering interconnection queue uncertainty. 2024 International Conference on Probabilistic Methods Applied to Power Systems. Institute of Electrical and Electronics Engineers, Piscataway, NJ, 2024.Google Scholar
- [28] . From zonal to nodal capacity expansion planning: Spatial aggregation impacts on a realistic test-case. Proceedings of the 2026 Power Systems Computation Conference. PSCC Papers Repository, Swiss Federal Institute of Technology, Lausanne, Switzerland, 2026.Google Scholar
- [29] . Assessing the economic value of co-optimized grid-scale energy storage investments in supporting high renewable portfolio standards. Applied Energy 183:902–913, 2016.Crossref, Google Scholar
- [30] . Power system expansion planning under uncertainty. IEEE Transactions on Power Systems 8(1):129–136, 1993.Crossref, Google Scholar
- [31] . Harnessing geothermal energy and emerging technologies to build a resilient electric grid in an evolving energy landscape. Geothermal Rising Conference 2025. Geothermal Resources Council Transactions, volume 49. Curran Associates, Red Hook, NY, 2025.Google Scholar
- [32] . A note on feasibility in Benders decomposition. Numerical Analysis Report NA/188, University of Dundee, Dundee, UK, 1999.Google Scholar
- [33] . Multiperiod stochastic optimization model for carbon capture and storage infrastructure under uncertainty in CO2 emissions, product prices, and operating costs. Industrial & Engineering Chemistry Research 51(35):11445–11457, 2012.Crossref, Google Scholar
- [34] . Pyomo: Modeling and solving mathematical programs in Python. Mathematical Programming Computation 3(3):219–260, 2011.Crossref, Google Scholar
- [35] .
Stochastic programming: Optimization when uncertainty matters . J. C. Smith, ed. Emerging Theory, Methods, and Applications, INFORMS TutORials in Operations Research. INFORMS, Catonsville, MD, 30–53, 2005.Link, Google Scholar - [36] . Capacity planning of renewable energy systems using stochastic dual dynamic programming. European Journal of Operational Research 322(2):573–588, 2025.Crossref, Google Scholar
- [37] . Parallelizing the dual revised simplex method. Mathematical Programming Computation 10(1):119–142, 2018.Crossref, Google Scholar
- [38] . A graph-based modeling abstraction for optimization: Concepts and implementation in Plasmo.jl. Mathematical Programming Computation 14:699–747, 2022.Crossref, Google Scholar
- [39]
JuMP . Two-stage stochastic programs. Accesssed March 31, 2026, https://jump.dev/JuMP.jl/stable/tutorials/applications/two_stage_stochastic/, 2026.Google Scholar - [40] .
Recent developments in multistage stochastic programming . A. Gupta and A. Capponi, eds. Optimization Challenges in Complex, Networked and Risky Systems, INFORMS TutORials in Operations Research. INFORMS, Catonsville, MD, 1–13, 2016.Link, Google Scholar - [41] . A parallel hub-and-spoke system for large-scale scenario-based optimization under uncertainty. Mathematical Programming Computation 15:591–619, 2023.Crossref, Google Scholar
- [42] . State-of-the-art generation expansion planning: A review. Applied Energy 230:563–589, 2018.Crossref, Google Scholar
- [43] .
An introduction to two-stage stochastic mixed-integer programming . R. Batta and J. Peng, eds. Leading Developments from INFORMS Communities, INFORMS TutORials in Operations Research. INFORMS, Catonsville, MD, 1–27, 2017.Link, Google Scholar - [44] . Deterministic electric power infrastructure planning: Mixed-integer programming model and nested decomposition algorithm. European Journal of Operational Research 271(3):1037–1054, 2018.Crossref, Google Scholar
- [45] . Decomposition algorithms for stochastic programming on a computational grid. Computational Optimization and Applications 24(2):207–250, 2003.Crossref, Google Scholar
- [46] . Multistage stochastic investment planning with multiscale representation of uncertainties and decisions. IEEE Transactions on Power Systems 33(1):781–791, 2018.Crossref, Google Scholar
- [47] . JuMP 1.0: Recent improvements to a modeling language for mathematical optimization. Mathematical Programming Computation 15(3):581–589, 2023.Crossref, Google Scholar
- [48] . The new challenges to transmission expansion planning. survey of recent practice and literature review. Electric Power Systems Research 134:19–29, 2016.Crossref, Google Scholar
- [49] . Monte Carlo bounding techniques for determining solution quality in stochastic programs. Operations Research Letters 24(1–2):47–56, 1999. Crossref, Google Scholar
- [50] J. B. Marco, R. Harboe, and J. D. Salas, eds. Stochastic Hydrology and Its Use in Water Resources Systems Simulation and Optimization, NATO Science Series E: Applied Sciences, volume 237. Springer, Dordrecht, Netherlands, 1993.Crossref, Google Scholar
- [51]
Midcontinent Independent System Operator . MTEP24 full report. Technical report, Midcontinent Independent System Operator, Carmel, Indiana, 2024.Google Scholar - [52] . A scalable solution framework for stochastic transmission and generation planning problems. Computational Management Science 12:491–518, 2015.Crossref, Google Scholar
- [53] . An engineering-economic approach to transmission planning under market and regulatory uncertainties: WECC case study. IEEE Transactions on Power Systems 29(1):307–317, 2014.Crossref, Google Scholar
- [54] . Climate-resilient nodal power system expansion planning for a realistic California test case. Preprint, submitted March 24, https://optimization-online.org/2025/03/climate-resilient-nodal-power-system-expansion-planning-for-a-realistic-california-test-case/, 2025.Google Scholar
- [55] . AI-assisted stochastic optimization for GPU data centers lifecycle planning. Proceedings of the 16th ACM International Conference on Future and Sustainable Energy Systems. Association for Computing Machinery, New York, 870–873, 2025.Google Scholar
- [56] .
Risk-averse stochastic modeling and optimization . E. Gel and L. Ntaimo, eds. Recent Advances in Optimization and Modeling of Contemporary Problems, INFORMS TutORials in Operations Research. INFORMS, Catonsville, MD, 221–254, 2018.Link, Google Scholar - [57] . Computational Stochastic Programming: Models, Algorithms, and Implementation, Springer Optimization and Its Applications, volume 774. Springer International Publishing, Cham, Switzerland, 2024.Crossref, Google Scholar
- [58] .
Clearing the jungle of stochastic optimization . A. Newman and J. Leung, eds. Bridging Data and Decisions, INFORMS TutORials in Operations Research. INFORMS, Catonsville, MD, 109–137, 2014.Link, Google Scholar - [59] .
A unified framework for optimization under uncertainty . A. Gupta and A. Capponi, eds. Optimization Challenges in Complex, Networked and Risky Systems, INFORMS TutORials in Operations Research. INFORMS, Catonsville, MD, 45–83, 2016.Link, Google Scholar - [60] . A unifying modeling abstraction for infinite-dimensional optimization. Computers & Chemical Engineering 156:107567, 2022.Crossref, Google Scholar
- [61] . Deployment of mobile switching centers in a telecommunications network: A stochastic programming approach. Telecommunication Systems 26:93–109, 2004.Crossref, Google Scholar
- [62] .
Stochastic programming models . A. Ruszczyński and A. Shapiro, eds. Stochastic Programming, Handbooks in Operations Research and Management Science, volume 10. Elsevier, Amsterdam, 1–64, 2003.Crossref, Google Scholar - [63] . Optimization-driven scenario grouping. INFORMS Journal on Computing 32(3):805–821, 2020.Link, Google Scholar
- [64] .
Stochastic facility location . Facility Location Under Uncertainty, International Series in Operations Research & Management Science, volume 356. Springer International Publishing, Cham, Switzerland, 123–179, 2024.Crossref, Google Scholar - [65] . Capacity expansion analysis of small modular reactors. Transactions of the American Nuclear Society 131(1):886–888, 2024.Crossref, Google Scholar
- [66] . Stochastic long-term joint decarbonization planning for power systems and data centers: A case study in PJM. International Journal of Electrical Power & Energy Systems 173:111377, 2025.Crossref, Google Scholar
- [67] . Solving multi-stage stochastic facility location problems with modular capacity adjustments. Computers & Operations Research 183:107200, 2025.Crossref, Google Scholar
- [68] . A stochastic optimization framework to planing for geographically correlated failures in coupled natural gas and electric power systems. Reliability Engineering & System Safety 246:110049, 2024.Crossref, Google Scholar
- [69] . Stochastic expansion planning model for a coordinated natural gas and electricity networks coupled with gas-fired generators, power-to-gas facilities, and renewable power. IEEE Access 12:105811–105830, 2024.Crossref, Google Scholar
- [70] . California test system (CATS): A geographically accurate test system based on the California grid. IEEE Transactions on Energy Markets, Policy and Regulation 2(1):107–118, 2024.Crossref, Google Scholar
- [71]
U.S. Energy Information Administration . Texas natural gas production fell by almost half during recent cold snap. Accessed March 21, 2026, https://www.eia.gov/todayinenergy/detail.php?id=46896, 2021.Google Scholar - [72]
U.S. Energy Information Administration . Electricity market module of the National Energy Modeling System: Model documentation 2025. Report, U.S. Energy Information Administration, Washington, DC, 2025.Google Scholar - [73] . Nodal capacity expansion planning with flexible large-scale load siting. Proceedings of the 24th Power Systems Computation Conference, Limassol, Cyprus. PSCC Papers Repository, Swiss Federal Institute of Technology, Lausanne, Switzerland, 2026.Google Scholar
- [74] . Parallel computing for power system climate resiliency: Solving a large-scale stochastic capacity expansion problem with mpi-sppy. Electric Power Systems Research 235:110720, 2024.Crossref, Google Scholar
- [75] .
Multi-period stochastic optimization of integrating carbon capture and storage/utilization (CCS/CCU) for cement industry . F. Manenti and G. V. Reklaitis, editiors. 34th European Symposium on Computer Aided Process Engineering/15th International Symposium on Process Systems Engineering, Computer Aided Chemical Engineering, volume 53. Elsevier, Amsterdam, 2101–2106, 2024.Crossref, Google Scholar - [76] . Progressive hedging innovations for a class of stochastic mixed-integer resource allocation problems. Computational Management Science 8:355–370, 2011.Crossref, Google Scholar
- [77] . Pyomo/mpi-sppy. Accesed July 21, 2026, https://github.com/Pyomo/mpi-sppy, 2025.Google Scholar
- [78] . Benders decomposition for stochastic facility location and production planning. Computers & Operations Research 186:107316, 2026.Crossref, Google Scholar
- [79] . Integrated planning of data center and distributed renewable energy in distribution systems. A. M. Foley, J. J. Klemeš, P. Varbanov, and T. Walmsley, eds. 2021 International Conference on Power System Technology. Institute of Electrical and Electronics Engineers, Piscataway, NJ, 308–312, 2021. Google Scholar
- [80] . Leveraging regional mesh refinement to simulate future climate projections for California using the simplified convection permitting E3SM atmosphere model version 0. Preprint, submitted August 31, https://doi.org/10.5194/egusphere-2023-1989, 2023.Google Scholar
- [81] . Risk management optimization framework for the optimal deployment of carbon capture and storage system under uncertainty. Renewable and Sustainable Energy Reviews 113:109280, 2019.Crossref, Google Scholar

