Electricity Mix: Nuclear or Renewables? Korea's 2026 Assembly Reopens a 2017 Question

In One Sentence

In 2024, nuclear quietly became Korea's largest single power source for the first time in history — 31.7% of generation (188.8 TWh), edging past coal (28.1%). At the same moment, renewables crossed the 10% threshold for the first time (10.6%, 63.2 TWh). Korea's first national Climate Citizens' Assembly (2026, 200 deliberating citizens — 20 planning + 180 deliberating-only — established under Article 19-2 of the Carbon Neutrality Framework Act) is now revisiting a question Korea has not directly put to its citizens since the 2017 Shin-Kori 5/6 deliberative poll: in the 2030 NDC path, which source should fill the space coal leaves behind?

Why This Matters — A Distinctly Korean Story

The 2024 Tipping Point

According to the Korea Power Exchange (KPX) 2024 market report, Korea's generation mix shifted in three directions at once:

• Nuclear: 31.7% (188.8 TWh) — historic high, single largest source
• Coal: 28.1% (167.2 TWh) — down 9.6% year-on-year
• LNG: 28.1% — up 6.0%, growing as a "bridge"
• Renewables: 10.6% (63.2 TWh) — first ever double-digit share

For citizens, the policy question becomes deceptively simple:

• Should nuclear take coal's retiring share?
• Should renewables plus transmission upgrades take it?
• Is LNG a bridge — or a multi-decade lock-in?

What Korea Learned in 2017

In 2017, Korea ran the Shin-Kori 5/6 deliberative poll — a 471-citizen panel asked whether to halt construction of two nuclear reactors. After three weeks, 59.5% recommended resuming construction. That precedent is the reason Korea's 2026 Assembly trusts that citizens can deliberate complex energy questions. But 2017 settled only one site. The 2026 Assembly inherits the unsettled mix question.

The Legal Frame Pulls Two Directions at Once

• Carbon Neutrality Framework Act §8 locks Korea's 2030 NDC at "≥40% reduction from 2018 levels" (2018 baseline: 727.6 Mt CO₂eq).
• The 11th Basic Plan for Electricity Supply and Demand (2024–2038) simultaneously expands nuclear (new large reactors planned), expands renewables, and approves new LNG capacity.
• RE100, the global corporate procurement standard, does not recognize nuclear as eligible — meaning Korean exporters like Samsung, SK, and LG face buyer pressure for renewables specifically, regardless of domestic policy.

The Assembly is asked, in effect, to deliberate whether Korea's domestic least-cost pathway and its export competitiveness pathway are pointing the same direction.

Disputes the Assembly Is Weighing

• Cost — Nuclear LCOE depends heavily on how safety, decommissioning, and grid-reinforcement externalities are accounted for. Renewables' headline cost is falling fast, but HVDC transmission from southwestern wind/solar zones to the Seoul capital region is a separate multi-trillion-won bill.
• Grid stability — Sustaining a ~30% nuclear share creates inertia and dispatch questions as variable renewables grow (covered in Session 1.2).
• International norms — RE100 and the EU's CBAM do not treat nuclear as a fully zero-carbon credit for traded goods.
• SMRs (Small Modular Reactors) — En-ROADS' user guide notes nuclear shows "very limited learning-curve effects, becoming relatively more expensive over time." Whether SMRs change that is itself disputed.
• Jobs and regions — Both nuclear complexes (Gyeongju, Ulsan, Busan) and renewable zones (Jeolla, Jeju) depend on local employment and tax bases.

In International Context

Reference	Korea's Position
France — ~66% nuclear, life-extending its existing fleet	Korea is now closer to France in share (31.7%) than at any time since 2015
Germany — completed nuclear phaseout in 2023	Korea has chosen the opposite direction in the 11th Basic Plan
UK — building Sizewell C, restarting nuclear after decades	Korea is also expanding, but with continuous build history, not a restart
RE100 (global) — renewables-only for member corporations	Korea's RE100 exporters face procurement pressure independent of grid mix

The Assembly is not being asked to copy any one of these models. It is being asked to weigh which lessons translate to a peninsula with limited interconnection, a dense industrial load, and a 2030 NDC already in law.

En-ROADS Lever Mapping

• L5 Nuclear (direct) — slider whose user guide explicitly flags a crowding-out dynamic: aggressive nuclear expansion can slow renewable investment.
• L4 Renewables (direct) — the lever that 2024 data shows Korea is already moving on, but from a low base.
• L1 Coal (indirect) — pace of coal retirement must be set jointly, or the gap is filled by gas (balloon effect).
• L3 Natural Gas (indirect) — the 11th Basic Plan's LNG expansion is effectively a third option already chosen by default.
• Moderator tip — if a small-group discussion tilts >30 minutes to one side, compare "L4 + L5 both maxed" vs "only one maxed" on the simulator to surface the trade-off concretely.

Open Questions Before the Assembly

• Is the 2024 nuclear share a target to maintain, a ceiling, or a transition peak?
• How should HVDC transmission cost be allocated — to Seoul ratepayers, to industrial users, or to general taxation?
• Should Korea's RE100 disadvantage trigger a domestic green-tariff redesign rather than a mix change?
• How does this agenda interact with Agenda ② (electricity pricing) and Agenda ⑬ (renewables allocation)?

The Assembly has not taken a position. Its recommendation, when issued, is advisory to the Presidential Committee on National Climate Crisis Response.

Citation

Korea Climate Assembly Wiki. (2026). Agenda #1 — Electricity Mix: Nuclear or Renewables? Retrieved from https://climate-assembly.org/en/agenda/nuclear-vs-renewable

Disclaimer

This page reflects deliberations of the 2026 Climate Citizens' Assembly, a consultative body established under Article 19-2 of Korea's Carbon Neutrality Framework Act. Recommendations of the Assembly are advisory and are submitted to the Presidential Committee on National Climate Crisis Response for review. This wiki is an independent moderator's archive, not an official publication of any Korean government body.