The Debate’s Starting Point is Electricity and Carbon’s Timetable
The question “solar or nuclear” always sounds like an exam forcing choice between two. However, South Korea’s power system isn’t an exam but reality, and reality usually doesn’t permit one-line answers. What this nation faces now isn’t a ‘preference’ problem but a ’timetable’ problem. Electricity becomes more necessary, and carbon must be reduced faster.
First, the demand side. The 11th Basic Plan for Long-term Electricity Supply and Demand sees power system consumption increasing from 557.1TWh in 2024 to 735.1TWh in 2038. Summer peak demand also grows from 104.2GW in 2024 to 145.6GW in 2038 over the same period. Not just ‘annual total usage’ but ‘instantaneous maximum’ grows more threateningly. This plan emphasizes particularly reflecting data centers (based on new electricity use applications, etc.) and electrification demand as “additional demand” separately. In other words, diagnosis that future power demand became difficult to explain with macro variables like economy and population alone.
Moreover, Korean electricity has large industrial proportions. The same plan summarizes that industrial power consumption proportions maintained above 50% in 2014-2023 trends (2023 basis: industrial 51.5%, commercial 33.8%, residential 14.6% displayed). Electricity is both ’living costs’ and simultaneously ‘manufacturing costs.’ So energy debates quickly spread into national discussions. When electricity rates rise, both factories and homes hurt.
Now the carbon side. Based on national reduction targets (NDC) organized by the Presidential Committee on Carbon Neutrality and Green Growth, the 2030 total emission target is 40% reduction from 2018 (727.6 → 436.6MtCO₂eq), with the transformation (power) sector presented as approximately 45.9% reduction from 2018 (269.6 → 145.9MtCO₂eq). To use electricity more as ’tools to reduce carbon’ (electrification), electricity itself must decarbonize faster structurally.
From here, “solar vs nuclear” appears. Not empty words—the administrative organization itself restructures centered on this problem. Looking at the Ministry of Climate and Environment minister introduction page, Kim Seong-hwan has served as minister since October 2025. Energy, climate, and environment bundling into one chunk signals electricity is no longer ‘a sub-item of industrial policy’ but became a central agenda of national operations.
Finally, Korea is also time-pressed from energy security aspects. 2024 provisional basis energy import dependency is presented as 93.7%. In structures depending on overseas for most energy, fuel price fluctuations and geopolitical risks directly hit electricity rates and industrial competitiveness. The reason “zero-carbon power expansion” is spoken in languages of not just climate but security and prices.
Solar Grows Fast, But Electricity Charges ‘Time-of-Day’ Tolls
Solar’s advantages are intuitive: builds quickly, can be divided small and spread around, doesn’t burn fuel. Moreover, costs fell significantly globally. The International Renewable Energy Agency summarizes that 2024 utility-scale solar’s global weighted average LCOE ‘stabilised’ around USD 0.043/kWh, 41% cheaper than the cheapest fossil fuel alternative. Basis arises for the story “became cheaper and likely continues cheapening.”
The problem is solar doesn’t automatically translate to ‘cheap electricity’ in Korea. Just looking at statistics operated by Korea Energy Economics Institute (renewable energy LCOE), Korean solar LCOE comes out quite differently by scenarios (assumptions). For example, 2024 solar (medium-scale) LCOE is sometimes presented as 132.0 won/kWh (forecast based on domestic deployment performance), with lower paths presented under other assumptions. The core is one: Korean solar costs are determined not just by ‘module prices’ but ‘pre-start costs’ like sites, permits, grid connection, and financing costs operate significantly.
Solar’s real trap isn’t just costs. The bigger trap is the physics that “electricity is difficult to store, and quality differs by time period.” Even equally 1kWh, 1kWh at 9 PM and 1kWh at weekday lunch differ in value from the grid’s perspective. Electricity needed at peak hours is expensive, and electricity remaining at surplus times has nowhere to go. At this time, solar has too distinct ‘good hours’ and ‘bad hours.’
This difference shows nakedly in statistics. Looking at Korea Power Exchange’s 2024 power system operation performance data, end-2024 solar installed capacity was 27,096MW, up 13.2% YoY. The same materials present 2024 utilization rates by generation source (approximate capacity factors) as nuclear 87%, solar 15%, wind approximately 22%. In other words, “facility installation speed” is fast but “hours electricity emerges (operating rate)” is slow.
What happens when installing lots of solar in this situation? Two things occur simultaneously.
First, the grid approaches ‘daytime excess.’ So output curtailment becomes a realistic option. The 11th Basic Plan writes premising solar and wind curtailment, setting annual curtailment rates around 3% level (basic assumption) with potential expansion to 5% level after 2035. Meaning “wasted electricity” can increase.
Second, the more solar grows, the more ‘grid stabilization resources’ are needed. Variability itself is problematic, but grid basic stamina like frequency, inertia, and reserves were originally designed centered on large rotating machines (thermal, nuclear, etc.). The 11th Basic Plan mentions synchronous condensers, inverter technology, and renewable-connected ESS for responding to grid instability from zero-carbon power expansion, specifying directions requiring solar and wind to secure self-flexibility (ESS integration, etc.) in “zero-carbon competitive markets.” Solar struggles becoming ‘first-string players in power systems’ just by laying panels, requiring sets with storage, grids, and market rules.
So Korea’s solar debates often roll not as ‘pro-environment vs anti-environment’ but as ‘site vs grid.’ Words like industrial complex solar, floating solar, parking lot solar, and setback regulation improvements repeatedly appear in the Basic Plan for this reason. “Willingness to increase solar” alone insufficient, simultaneously requiring “space for solar to enter” and “paths to carry that electricity.”
Nuclear ‘Generates Well’ But Society Asks Long and Remembers Long
Nuclear’s advantages lie at exact opposite points from solar. The biggest weapon is ‘operating rate.’ In KPX’s 2024 system operation performance, nuclear utilization rate is presented as 87%. In the same document, 2024 generation performance is organized as nuclear 188,890GWh (33.0%). Because the ratio of time generating facilities actually extract electricity is high, from the grid’s perspective it operates as “predictable stamina.”
An interesting scene emerges here. Looking at end-2024 installed capacity, nuclear is 26,050MW while renewable is 34,693MW. Numbers alone show renewable larger. However, looking at generation amounts and grid contributions, nuclear’s presence is far larger. This means nuclear has “wide time periods capable of producing electricity” while simultaneously meaning solar “pays time-period tolls.”
This doesn’t mean nuclear is a wild card though. Nuclear’s biggest constraint is the fact that “timetables are long.” The 11th Basic Plan writes premised on already-planned new nuclear (e.g., 2024-2026, Shin-Hanul Unit 2 and Shin-Ulchin Units 3-4 completion) that nuclear facilities increase from 2023’s 24.7GW to 2030’s 28.9GW, presented at 2035/2038 levels around 31.7GW.
However, the next cards (additional large nuclear) are far slower. The Basic Plan mentions “new large nuclear” construction periods as 167 months on operator submission basis, presenting flows like 2026 site confirmation → 2029 related permits → 2037-2038 construction/completion on schedule. Literally “even deciding now, electricity comes much later.” So whether advocating nuclear expansion or opposing it, both ultimately converge to the problem of surviving in the narrow section called ’early 2030s’ with what combinations.
The reason nuclear is trickier in Korean society is not just safety itself debates but because the “time bomb” called spent nuclear fuel always appears as realistic schedules. The 「Special Act on Management of High-Level Radioactive Waste」 enforced from October 1, 2025, stipulates matters regarding high-level radioactive waste management principles and procedures, management facility site selection, etc. In other words, meaning national-level governance was legally established for “what to do with what already emerged” separately from ‘more/less nuclear use.’
Saturation schedules are also treated as administrative materials not political rhetoric. In 2023 Ministry of Trade, Industry and Energy press release format articles (pages republished as economic news), spent nuclear fuel storage facility saturation timing was publicly disclosed as expected 2030 Hanbit, 2031 Hanul, 2032 Gori in order, writing this forecast shortened 1-2 years compared to December 2021 forecast. The interpretation emerging here is “nuclear is already existing power, and now it’s a section where waste management’s administrative time catches up to power policy time.”
So nuclear is simultaneously ’technology generating electricity well’ and ’technology society asks long and remembers long.’ The Basic Plan writing together continued operation promotion (continued operation of operating license-expired nuclear), acceptance securing efforts (resident opinion gathering, etc.), and further mentioning mid-2030s large nuclear flexible operation commercialization is also this context. The order that nuclear shouldn’t just stand as baseload but must partially handle grid flexibility after renewable expansion.
The Selection Finals are Not Power Plants But Grids and Systems
If solar and nuclear are ultimately “power plant” stories, energy mix’s real substance is “grids.” Power plants make electricity. Grids fit that electricity ‘where needed, when needed, at needed quality.’ This isn’t simple metaphor—the plan document structure itself says it. The 11th Basic Plan table of contents continues after policy directions by generation source to generation facility plans, Jeju supply-demand forecasts, distributed energy activation, transmission/substation facility plans, and power market improvement directions. The next page after “which generation source is good” is “so how will we lay transmission lines, how will we change markets.”
When transmission networks become bottlenecks, solar suffers curtailment, coal also runs less due to transmission constraints, and even overall operating costs distort. Korea Energy Economics Institute’s supply-demand trend materials sometimes mention insufficient transmission lines causing transmission constraints as reasons for coal generation plunges. In other words, ‘bottlenecks’ rather than generation source ‘preferences’ determine actual results.
To solve this bottleneck, the government started moving law and committee systems simultaneously while including long-term transmission/substation plans in the Basic Plan. The 「Special Act on Expansion of National Infrastructure Power Grids」 states in purpose clauses early expansion of power grid facilities needed for stable supply of electrical energy, industrial competitiveness strengthening, renewable energy expansion, etc. In legislation notice/enactment guidance (Ministry of Government Legislation, legislation notice system, etc.), keywords like timely expansion of 345kV+ national infrastructure grids, state-led governance, ultra-long-term basic plan establishment, permit expediting, and resident/local government support strengthening are fronted. This is an attempt to frontally break through with systems the reality of solar/nuclear debates ‘concluding in transmission line complaints.’
Demand management is also the same context. Not just making more electricity finishes it—shaving peaks (reducing most expensive electricity hours) and dispersing demand reduces system costs. The 11th Basic Plan set 2038 demand management targets at 16.3GW, presenting 2038 7.5GW savings on peak basis premised on Energy Supplier Efficiency Rating (EERS) promotion. Creating “unused electricity” becomes as important as building new power plants.
At this point, solar and nuclear become mirrors revealing each other’s weaknesses rather than ‘replacing’ each other.
- The more solar grows, the more flexible grids must become (ESS, synchronous condensers, market rules), and what currently best provides that flexibility is usually LNG or some flexible operation resources. The reason the Basic Plan keeps LNG at 25.1% share even in 2030 is here.
- The more nuclear grows, the more grids must manage ’large power source dependency risks’ (maintenance, failures, regional concentration) while simultaneously solving social timetables like spent fuel and continued operation.
Ultimately, energy mix isn’t technology battles but operation battles, and operations are battles of systems, infrastructure, and acceptance (politics).
The Conclusion is Sequence Rather Than Ratios
Independently reconstructing Korea’s energy mix debate simplifies conclusions: not “solar or nuclear” but “what buys time until early 2030s, and what gets laid down in that time.”
Numbers the Basic Plan presents force this conclusion. 2023 actual basis generation proportions are organized as nuclear 30.7%, coal 31.4%, LNG 26.8%, renewable energy 8.4%, etc. However, 2030 forecasts show nuclear 31.8%, renewable energy 18.8% with renewable significantly growing, coal shrinking to 17.2%, and ‘zero-carbon generation proportion’ (nuclear+renewable+clean hydrogen+ammonia, etc.) set rising to 53.0%. With more time passing, 2038 presents 70.7% zero-carbon proportion target (same table shows nuclear 35.2%, renewable 29.2%, etc.), with coal and LNG each shrinking to 10.1% and 10.6%. Meaning “simultaneous nuclear+renewable expansion” is laid as policy document baseline.
For such roadmaps to roll in reality requires ‘sequence.’
First, solar can grow now and going forward. However, grid costs (networks, storage, flexibility) attach as much as growth. So solar expansion must package-manage operating conditions like curtailment, ESS integration, and grid connection delay resolution together with generation targets. The reason the Basic Plan nailed details like curtailment rates and zero-carbon competitive market flexibility requirements into documents is here.
Second, nuclear is powerful at reducing carbon without greatly shaking “existing electricity.” However, new large nuclear is slow. Therefore, until early 2030s, ‘operation-based expansions’ like new completions (already planned units), continued operation (lifetime extensions), and grid flexibility (flexible operation) become important. Simultaneously, spent fuel management law and governance must operate as actual schedules.
Third, grid expansion is common premises across all scenarios. Whether nuclear-centered or solar-centered, if transmission networks clog, electricity rots in place. So special acts emerged, and ‘political determinations’ to nationally drive 345kV+ infrastructure grids attach. If this succeeds, renewable energy expansion also accelerates (grid connection, acceptance), and power from nuclear and large generation regions flows more stably to metropolitan/industrial complex areas. If it fails, any power source remains in ‘plans.’
Summarizing, solar and nuclear are closer to teammates taking different roles (speed vs stability) required by Korea’s power system rather than competitors existing to defeat each other. However, for the two to run as the same team requires rules: rules called grids, markets, and acceptance. From the moment of designing and passing these rules, energy problems shift from technology to democracy problems. The reason the phrase “national discussion” isn’t pie in the sky.
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