The showcase’s starting point in energy research

Which climate policy instruments do governments use, and which ones have been academically studied? A research article by NFDI4Energy members uses the NFDI4Energy Climate and Energy Policy Ontology (CEPO) to test this question. The ontology is used to code and analyze a global database of policy effectiveness studies (1990–2024) and compare research patterns with real-world policy implementation. The paper finds that studies focus disproportionately on a small subset of economic instruments such as carbon taxes and emissions trading systems, while many widely-implemented regulatory instruments remain largely unevaluated. Research is also heavily skewed towards a limited set of developed countries and China, leaving most jurisdictions with implemented policies empirically unexplored. By mapping the literature onto a structured policy instrument ontology, we show that these research gaps are not random but aligned with specific branches of the instrument space – particularly regulatory instruments. This highlights the need for improved data infrastructures built on clear, interoperable policy ontologies to enable cumulative, comparable, and systematic evaluation of climate policy.

Motivation and research requirements

While several attempts at gathering and publishing climate policy instrument data exist, they do not share a unified ontology on climate policy instruments. This means that climate policy data lacks interoperability and cannot be combined across sources – hindering researchers from being able to analyze policy. This, in turn, limits empirical knowledge as research is often limited to the few cases with good data availability; multi-case and cross-temporal policy instrument analysis is rare. We needed an ontology which was both granular and interoperable with the high-level climate policy databases (CPDB and CPR) to be able to assess the academic literature in some detail and then compare it to the policy instruments that exist.

NFDI4Energy solution

The Climate and Energy Policy Ontology (CEPO) is an ontology for climate and energy policy instruments integrated into the OEO Family and developed in collaboration with the Energy-related reference ontologies (ENERO) Foundry. This ontology is at once detailed and interoperable with typologies that institutions use to gather climate policy data from Climate Policy Database (CPDB) and Climate Policy Radar (CPR). Using this ontology to categorize data and academic articles, we show that under-conceptualized instruments are also less-studied, and that there is an overwhelming focus on a few countries and instruments (particularly OECD countries and carbon pricing). In order to show the ontology to users who are not accustomed to OWL/Github, we have also created an online tool to visualize the ontology, making it more accessible to researchers from the social sciences and potential policy users.

Link collection

• CEPO Repository: GitHub – ClimateEnergyPolicyOntology
• Easy-to-use Version: Climate Policy Atlas Website
• Ontology Draft (Zenodo)

NFDI4Energy input

• NFDI4Energy Deliverable 4.5.1.1: Draft Climate Policy Ontology

Task Areas involved

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