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Field guide

Nuclear energy

Huge energy from tiny atoms—plus decades of debate about waste, wallets, and "what if."

Overview

Nuclear fission releases heat to produce electricity with low direct CO₂ emissions from the plant. IPCC AR6 WGIII notes nuclear accounted for about 10% of global electricity generation in 2019. Debates focus on safety, waste, cost, and safeguards, alongside firm low-carbon electricity provision.

By the numbers

Evidence highlights

3 beats
  1. 01

    IPCC AR6 WGIII reports nuclear generation grew about 9% between 2015 and 2019 and accounted for roughly 10% of total generation in 2019 (2790 TWh).

  2. 02

    Assessment scenarios that limit warming typically include diverse low-carbon portfolios; feasibility depends on regional context, regulation, and public acceptance.

  3. 03

    High-level radioactive waste and decommissioning require long-term governance and geotechnical siting; institutions differ across countries.

Chart

Explore the data

Electricity generation from nuclear power (terawatt-hours). Change region or year in the chart; see the grapher page for data sources and units.

Chart: Our World in Data (CC BY). Each grapher page lists the underlying datasets, units, and processing notes—use it when citing numbers.

Open on Our World in Data

Trade-offs

Where it helps—and where it hurts

Strengths

  • Can supply large-scale, dispatchable electricity without combustion-related CO₂ from the plant itself.
  • Small land footprint per unit electricity compared with many renewables at typical project densities.
  • Mature safety and safeguards frameworks exist in many countries, though performance depends on implementation.

Limits & trade-offs

  • High upfront capital costs and long lead times; financing and construction risk can constrain new projects.
  • Severe accidents are rare but consequential; safety culture, independence of regulators, and transparency matter.
  • Waste stewardship and proliferation concerns require durable institutions and international cooperation.

References

Sources for this page

These entries are starting points for verification. Prefer the original report or dataset when checking numbers and figures.

  1. IPCC AR6 WGIII Ch. 6Clarke, L., Wei, Y.-M., De La Vega Navarro, A., Garg, A., Hahmann, A. N., Khennas, S., Azevedo, I. M. L., Loschel, A., Singh, A. K., Steg, L., Strbac, G., & Wada, K. (2022). Energy systems. In P. R. Shukla et al. (Eds.), Climate Change 2022: Mitigation of Climate Change (IPCC AR6 WGIII, Chapter 6). Cambridge University Press. https://doi.org/10.1017/9781009157926.008
  2. IAEA nuclear overviewInternational Atomic Energy Agency. (2025). Nuclear power reactors in the world (Reference Data Series No. 2, 45th ed.). IAEA. https://doi.org/10.61092/iaea.1g28-w3uk
  3. IPCC AR6 WGIII Technical SummaryPathak, M., Slade, R., Shukla, P. R., Skea, J., Pichs-Madruga, R., & Urge-Vorsatz, D. (2022). Technical summary. In P. R. Shukla et al. (Eds.), Climate Change 2022: Mitigation of Climate Change (IPCC AR6 WGIII). Cambridge University Press. https://doi.org/10.1017/9781009157926.002
  4. Our World in DataRitchie, H., & Rosado, P. (2020). Electricity mix. Our World in Data. https://ourworldindata.org/electricity-mix (underlying grapher datasets include Ember and Energy Institute series, cited per chart metadata).