
Mathijs Bijkerk developed and maintained advanced energy system modeling features in the quintel/etsource and quintel/etlocal repositories, focusing on data integrity, modular query design, and scenario analysis. He engineered GraphQL-based data access, refined emissions calculations, and improved dataset management for regional and sector-specific energy flows. Using Ruby, YAML, and CSV, Mathijs implemented configuration cleanups, enhanced data visualization, and optimized backend data pipelines to support accurate forecasting and policy analysis. His work demonstrated depth in backend development, data modeling, and configuration management, resulting in more reliable reporting, maintainable codebases, and improved decision support for energy planning and compliance.
January 2026 monthly summary for quintel/etsource. Focused on modularizing data queries, refining emissions calculations, and enhancing input fidelity for demand modeling. Delivered GraphQL query refactor and emissions calculation improvements, removed outdated hydrogen queries, and added separate sliders for lighting and appliances, enabling granular inputs and separate efficiency/demand calculations. These changes improve reporting accuracy, reduce technical debt, and support more precise scenario planning for energy systems.
January 2026 monthly summary for quintel/etsource. Focused on modularizing data queries, refining emissions calculations, and enhancing input fidelity for demand modeling. Delivered GraphQL query refactor and emissions calculation improvements, removed outdated hydrogen queries, and added separate sliders for lighting and appliances, enabling granular inputs and separate efficiency/demand calculations. These changes improve reporting accuracy, reduce technical debt, and support more precise scenario planning for energy systems.
December 2025 – quintel/etlocal: Delivered an important compatibility upgrade by bumping the Atlas gem to quintel/atlas@8db16bb, enabling alignment with the latest Atlas features and reducing risk of regressions for upcoming work. This strengthens the foundation for feature expansions and long-term stability across dependent services. No major bugs reported or fixed this month. Impact includes improved maintainability, smoother downstream integrations, and a clearer upgrade path for future capability enhancements. Technologies/skills demonstrated include Ruby gem management, Bundler dependency pinning, version control discipline, and cross-team collaboration for compatibility validation.
December 2025 – quintel/etlocal: Delivered an important compatibility upgrade by bumping the Atlas gem to quintel/atlas@8db16bb, enabling alignment with the latest Atlas features and reducing risk of regressions for upcoming work. This strengthens the foundation for feature expansions and long-term stability across dependent services. No major bugs reported or fixed this month. Impact includes improved maintainability, smoother downstream integrations, and a clearer upgrade path for future capability enhancements. Technologies/skills demonstrated include Ruby gem management, Bundler dependency pinning, version control discipline, and cross-team collaboration for compatibility validation.
November 2025 recap: delivered targeted data accuracy and readability improvements across quintel/etlocal and quintel/etsource, focused on Norway and Serbia aluminium datasets. Implemented migrations to update aluminium production and demand data, refreshing metrics to reflect energy input sources and their shares. Enhanced query formatting and expression clarity to improve maintainability and reduce ambiguity without changing functionality. These improvements strengthen data integrity for energy-system modeling, enable better decision-making for planning and policy, and demonstrate effective cross-repo collaboration.
November 2025 recap: delivered targeted data accuracy and readability improvements across quintel/etlocal and quintel/etsource, focused on Norway and Serbia aluminium datasets. Implemented migrations to update aluminium production and demand data, refreshing metrics to reflect energy input sources and their shares. Enhanced query formatting and expression clarity to improve maintainability and reduce ambiguity without changing functionality. These improvements strengthen data integrity for energy-system modeling, enable better decision-making for planning and policy, and demonstrate effective cross-repo collaboration.
In October 2025, cross-repo work across quintel/etsource and quintel/etlocal focused on improving modeling accuracy, user experience, and maintainability. Key work delivered includes precision enhancements for refinery input processing, corrections to carbon-modeling coordinates, a major reorganization of area attributes and geography configuration, UI text and localization improvements, and standardized energy losses configuration with locale updates. These efforts reduce modeling errors, clarify configuration for users, and enable more reliable decision support for energy scenarios.
In October 2025, cross-repo work across quintel/etsource and quintel/etlocal focused on improving modeling accuracy, user experience, and maintainability. Key work delivered includes precision enhancements for refinery input processing, corrections to carbon-modeling coordinates, a major reorganization of area attributes and geography configuration, UI text and localization improvements, and standardized energy losses configuration with locale updates. These efforts reduce modeling errors, clarify configuration for users, and enable more reliable decision support for energy scenarios.
September 2025 monthly work summary focusing on key accomplishments and business value for quintel/etsource. This period prioritized data integrity, model fidelity, and delivery of business-ready improvements across energy system datasets, refinery modeling, and software dependencies. The work enhances decision support with more accurate demand estimation, energy balance, and policy-aligned emissions accounting.
September 2025 monthly work summary focusing on key accomplishments and business value for quintel/etsource. This period prioritized data integrity, model fidelity, and delivery of business-ready improvements across energy system datasets, refinery modeling, and software dependencies. The work enhances decision support with more accurate demand estimation, energy balance, and policy-aligned emissions accounting.
Performance summary for 2025-08: Delivered data parameter updates, a new electricity production chart query, NL2023 dataset enhancements, and targeted bug fixes. These changes improve modeling accuracy, chart reliability, and NL2023 scenario readiness, delivering clearer business insights and policy support for NL markets and EU ETS.
Performance summary for 2025-08: Delivered data parameter updates, a new electricity production chart query, NL2023 dataset enhancements, and targeted bug fixes. These changes improve modeling accuracy, chart reliability, and NL2023 scenario readiness, delivering clearer business insights and policy support for NL markets and EU ETS.
July 2025: Across quintel/etsource and quintel/etlocal, delivered cross-repo data and modeling enhancements, improved data integrity, and expanded analytics capabilities that strengthen energy scenario planning and business decision support. Key work included comprehensive data refinements (notably industry data corrections with naphtha splits in EU2011/NL2015 and revised emission grouping), GraphQL-based access to cooling energy input, refinery gas external coupling with Sankey visualization, and dataset quality enrichments for NL2019 plus NL2023 integration. Standardized boolean inputs for heat storage, and maintained dependencies with Atlas gem upgrades. Addressed core defects in refinery energetic demand calculations and clarified oil usage descriptions in locale resources, boosting accuracy and user trust.
July 2025: Across quintel/etsource and quintel/etlocal, delivered cross-repo data and modeling enhancements, improved data integrity, and expanded analytics capabilities that strengthen energy scenario planning and business decision support. Key work included comprehensive data refinements (notably industry data corrections with naphtha splits in EU2011/NL2015 and revised emission grouping), GraphQL-based access to cooling energy input, refinery gas external coupling with Sankey visualization, and dataset quality enrichments for NL2019 plus NL2023 integration. Standardized boolean inputs for heat storage, and maintained dependencies with Atlas gem upgrades. Addressed core defects in refinery energetic demand calculations and clarified oil usage descriptions in locale resources, boosting accuracy and user trust.
June 2025 monthly summary for quintel/etsource focused on simplifying configuration, enhancing energy flow modeling, and stabilizing lifetime calculations to improve data integrity and modeling accuracy.
June 2025 monthly summary for quintel/etsource focused on simplifying configuration, enhancing energy flow modeling, and stabilizing lifetime calculations to improve data integrity and modeling accuracy.
In May 2025, completed a focused model-cleanup in quintel/etsource by removing deprecated household configuration files and outdated energy node attributes, reducing technical debt and clarifying the modeling surface for forecasting and energy demand. This work improves maintainability, reduces potential misconfigurations, and prepares the codebase for upcoming feature work.
In May 2025, completed a focused model-cleanup in quintel/etsource by removing deprecated household configuration files and outdated energy node attributes, reducing technical debt and clarifying the modeling surface for forecasting and energy demand. This work improves maintainability, reduces potential misconfigurations, and prepares the codebase for upcoming feature work.
April 2025 – quintel/etsource: Delivered targeted enhancements to energy modeling and visualization that add business value and improve analytics clarity. Implemented a bug fix for the Energy Graph Final Demand that ensures DSR demand is included in ICT sector final demand and consolidates ICT demand under a single edge group, improving energy demand calculation accuracy. Also shipped Energy Diagram Visualization Enhancements to unify appliance efficiency controls and optimize node layout for clearer energy consumption visuals. These changes tighten data modeling, streamline UI controls, and set the stage for more reliable scenario analyses.
April 2025 – quintel/etsource: Delivered targeted enhancements to energy modeling and visualization that add business value and improve analytics clarity. Implemented a bug fix for the Energy Graph Final Demand that ensures DSR demand is included in ICT sector final demand and consolidates ICT demand under a single edge group, improving energy demand calculation accuracy. Also shipped Energy Diagram Visualization Enhancements to unify appliance efficiency controls and optimize node layout for clearer energy consumption visuals. These changes tighten data modeling, streamline UI controls, and set the stage for more reliable scenario analyses.
March 2025: Delivered two key contributions to quintel/etsource that drive business value: (1) Hide PV NH 2019 dataset in Etmodel front-end, reducing confusion by hiding outdated data while keeping PV NH 2022 visible; (2) Improve energy graph visualization layout by adjusting x/y coordinates for energy-related nodes to enhance clarity without altering functionality. No major bugs fixed this month. Impact: cleaner dataset presentation reduces user error and accelerates analysis; clearer energy graphs improve quick insight extraction and decision making. Technologies/skills: front-end feature flagging and dataset control, graph visualization tuning, attention to UX clarity and maintainability.
March 2025: Delivered two key contributions to quintel/etsource that drive business value: (1) Hide PV NH 2019 dataset in Etmodel front-end, reducing confusion by hiding outdated data while keeping PV NH 2022 visible; (2) Improve energy graph visualization layout by adjusting x/y coordinates for energy-related nodes to enhance clarity without altering functionality. No major bugs fixed this month. Impact: cleaner dataset presentation reduces user error and accelerates analysis; clearer energy graphs improve quick insight extraction and decision making. Technologies/skills: front-end feature flagging and dataset control, graph visualization tuning, attention to UX clarity and maintainability.
February 2025 monthly summary for quintel/etsource. Delivered targeted feature enhancements to hydrogen energy flow modeling and MT Sankey visualizations, addressed data constraints across insulation inputs, and fixed a GraphQL reference typo. Resulted in more accurate energy system representations, expanded visualization coverage, and clearer developer documentation. Maintains robust model fidelity while broadening scenario analysis capabilities.
February 2025 monthly summary for quintel/etsource. Delivered targeted feature enhancements to hydrogen energy flow modeling and MT Sankey visualizations, addressed data constraints across insulation inputs, and fixed a GraphQL reference typo. Resulted in more accurate energy system representations, expanded visualization coverage, and clearer developer documentation. Maintains robust model fidelity while broadening scenario analysis capabilities.
Month: 2025-01. This monthly summary highlights data quality and maintainability improvements in quintel/etsource, focusing on energy modeling data correctness, PV input parameter calculations, and codebase readability. Key work included data classification refinements for energy modeling, PV input fix-ups, and GraphQL query refactoring. Impact: more accurate energy production figures, improved reproducibility, and faster developer onboarding and maintenance.
Month: 2025-01. This monthly summary highlights data quality and maintainability improvements in quintel/etsource, focusing on energy modeling data correctness, PV input parameter calculations, and codebase readability. Key work included data classification refinements for energy modeling, PV input fix-ups, and GraphQL query refactoring. Impact: more accurate energy production figures, improved reproducibility, and faster developer onboarding and maintenance.
December 2024: Implemented targeted data integrity and modeling enhancements for the energy-system model in quintel/etsource. Key outcomes include harmonizing DAC heat network configurations across hourly and annual views, introducing GraphQL queries for DSR installed capacity, performing dataset hygiene by removing outdated entries, and correcting the aluminium external coupling production input source. These changes improve data consistency, reporting accuracy, and modeling reliability, enabling better decision support for energy planning and policy analysis.
December 2024: Implemented targeted data integrity and modeling enhancements for the energy-system model in quintel/etsource. Key outcomes include harmonizing DAC heat network configurations across hourly and annual views, introducing GraphQL queries for DSR installed capacity, performing dataset hygiene by removing outdated entries, and correcting the aluminium external coupling production input source. These changes improve data consistency, reporting accuracy, and modeling reliability, enabling better decision support for energy planning and policy analysis.
2024-11 Monthly Summary: Delivered GraphQL-based industry CO2 emissions queries in quintel/etsource to enable granular reporting and analysis. The feature provides breakdowns by energy sources and specific industrial inputs for precise environmental reporting and analytics. Change tracked under commit 5ea24b8decf12e1990146b7eda87314599672aff. No major bugs reported or fixed this month. Overall impact improves data-driven sustainability decisions, compliance readiness, and visibility into industry-sector emissions. Demonstrated strong GraphQL API design, data modeling, and end-to-end feature delivery using version-controlled commits.
2024-11 Monthly Summary: Delivered GraphQL-based industry CO2 emissions queries in quintel/etsource to enable granular reporting and analysis. The feature provides breakdowns by energy sources and specific industrial inputs for precise environmental reporting and analytics. Change tracked under commit 5ea24b8decf12e1990146b7eda87314599672aff. No major bugs reported or fixed this month. Overall impact improves data-driven sustainability decisions, compliance readiness, and visibility into industry-sector emissions. Demonstrated strong GraphQL API design, data modeling, and end-to-end feature delivery using version-controlled commits.

Overview of all repositories you've contributed to across your timeline