Zaporizhzhia Nuclear Power Plant Energy Deficit

Introduction

Fig. 1: Ukraine electricity generation comparison showing Zaporizhzhia's 40 TWh represents 25% of 2021 pre-war output and 39% of 2023 wartime generation. [4] (Image source: N. Oliinyk)

The Zaporizhzhia Nuclear Power Plant is the largest nuclear facility in Europe. [1] Located in southeastern Ukraine, it has been offline since March 2022 due to Russian military occupation. [2] This paper quantifies the energy deficit created by the plant shutdown and evaluates the carbon implications of replacing nuclear generation with fossil fuel alternatives.

Plant Capacity and Energy Output

Zaporizhzhia operates six Soviet-designed VVER-1000 pressurized water reactors with a combined nameplate capacity of 5.7 gigawatts. [3] Before the war, Ukrainian nuclear plants maintained an average capacity factor of approximately 80%, reflecting scheduled maintenance and refueling cycles. At this operational level, Zaporizhzhia generated 40 terawatt-hours annually equivalent to 1.4 × 10¹⁷ joules per year. This represented approximately 25% of Ukraine's total electricity generation in 2021. Fig. 1 compares Ukraine energy production in 2021 and 2023. [4]

Replacement with Natural Gas

If Ukraine were to replace Zaporizhzhia's lost capacity with modern combined-cycle gas turbines operating at 50% thermal efficiency, the required fuel input would be 2.9 × 10¹⁷ joules annually. Natural gas has an energy density of approximately 5.5 × 10⁷ joules per cubic meter. Therefore, full replacement would require 5.2 billion cubic meters of natural gas per year, roughly one-third of Ukraine's pre-war residential gas consumption. [5]

Combusting this quantity of natural gas would produce approximately 16 million tonnes of CO₂ annually, based on the IPCC emission factor of 56.1 kg CO₂ per gigajoule. For perspective, this emission level exceeds the annual carbon footprint of approximately 3.5 million passenger vehicles. The loss of nuclear baseload capacity thus creates both an energy security challenge and a significant climate penalty if replaced with fossil generation.

Key operational and replacement parameters for Zaporizhzhia NPP are summarized in Table 1.

Current Energy Situation

Ukraine has not fully replaced Zaporizhzhia's output. Instead, the country has adapted through multiple mechanisms. European neighbors provided approximately 2 TWh of imported electricity in 2023. Remaining coal-fired plants increased generation by an estimated 5 TWh despite environmental concerns. Thermal plants burning natural gas and fuel oil contributed roughly 8 TWh. The balance has been absorbed through industrial shutdown, conservation measures, and rolling blackouts in urban areas. [4]

The plant's spent nuclear fuel remains on-site in cooling pools and dry storage casks. International Atomic Energy Agency personnel continue monitoring the facility under difficult conditions. Long-term management of radioactive waste will require eventual restoration of Ukrainian control and international assistance for safe decommissioning or restart operations.

Conclusion

The shutdown of Zaporizhzhia Nuclear Power Plant has eliminated 40 terawatt-hours of annual low-carbon electricity generation. Full replacement with natural gas would require over 5 billion cubic meters of fuel and produce 16 million tonnes of CO₂ emissions annually. Ukraine has partially compensated through imports, increased fossil generation, and demand reduction, but has not restored the lost capacity. The plant's status remains uncertain, with spent fuel management dependent on future political and military developments. The energy deficit illustrates the strategic vulnerability created when large baseload power facilities become casualties of armed conflict.

© Nazar Oliinyk. The author warrants that the work is the author's own and that Stanford University provided no input other than typesetting and referencing guidelines. The author grants permission to copy, distribute and display this work in unaltered form, with attribution to the author, for noncommercial purposes only. All other rights, including commercial rights, are reserved to the author.

References

[1] C. Wahlquist and D. Lu, "Zaporizhzhia Nuclear Power Plant: Everything You Need to Know," The Guardian, 4 Mar 22.

[2] P. Polityuk and O. Harmash, "Ukraine's Natural Gas Consumption Slumps Due to War, Naftogaz CEO Says," Reuters, 22 Sep 23.

[3] "Nuclear Power Reactors in the World," International Atomic Energy Agency, IAEA-RDS-2/44, 2024.

[4] "Country Analysis Brief: Ukraine," U.S. Energy Information Administration, June 25.

[5] P. Polityuk and O. Harmash, "Ukraine's Natural Gas Consumption Slumps Due to War, Naftogaz CEO Says," Reuters, 22 Sep 23.