React FAQ
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How many nuclear reactors would it take to power San Diego?

The San Diego–Chula Vista–Carlsbad, CA metro area is home to 3,282,248 people. Below: scenario estimates of how many reactors of various sizes would be required to cover its annual electricity demand — and what it would take with other power sources.

Population
3,282,248
Annual electricity demand
19,845,746 MWh
Primary state
CA
Today's grid mix
eGRID 2023 subregion CAMX — WECC California
43% Natural gas
largest source · 2023
Natural gas 42.9%
Solar 20.1%
Hydro 14.1%
Nuclear 8.0%
Wind 6.6%
Other 6.5%
Coal 2.1%

Replacing the fossil portion (45% of generation) with nuclear would avoid roughly 1,913,378–4,279,090 tons of CO₂ per year for this metro's share of demand. Range uses EPA eGRID 2023 Total Output rate (low) and Non-baseload rate (high) for CAMX. See methodology.

Annual electricity demand
CA state total — all sectors
-4.0%
2001 → 2025
0125M250M375M500M200120052010201520202025

Reactors needed

Each row shows how many of one reactor type would cover annual demand. Icons scale with count — fewer big reactors, many more small ones.

Advanced Microreactor (10 MWe representative)
10 MWe per unit · 90% capacity factor
252
reactors needed
Small SMR Module (77 MWe, NuScale-class)
77 MWe per unit · 93% capacity factor
32
reactors needed
Large SMR (300 MWe, BWRX-300 class)
300 MWe per unit · 93% capacity factor
9
reactors needed
Large Reactor (1,117 MWe, AP1000 class)
1,117 MWe per unit · 93% capacity factor
3
reactors needed

Or with other power sources

Counts assume same annual MWh. Variable sources (solar, wind) would need additional storage or backup to provide firm equivalent power — disclosed per card. Land use is typical farm/plant footprint; CO₂ is operational rate × annual demand.

Nuclear · Large
Large nuclear reactor
Raw count (same annual MWh)
3
units needed
Land
3.9 sq mi
Cap. factor
93%
CO₂
Zero

Firm baseload. Long build times, high upfront cost.

Nuclear · SMR
Small SMR module
Raw count (same annual MWh)
32
units needed
Land
1.8 sq mi
Cap. factor
93%
CO₂
Zero

Firm baseload. Pre-commercial in the U.S.

Solar
Utility solar farm (100 MW DC)
Raw count (same annual MWh)
91
units needed ≈ 22.8M panels (≈400W each)
Firm equivalent (with storage)
228–364
units needed for 24/7 firm power ≈ 57.0M–91.0M panels (≈400W each)
Land
85.3 sq mi
Cap. factor
25%
CO₂
Zero

Variable output. Raw count assumes same annual MWh; firm equivalent accounts for storage and oversizing needed for 24/7 power.

Wind
Onshore wind turbine (3 MW)
Raw count (same annual MWh)
2,158
units needed
Firm equivalent (with storage)
4,885–6,474
units needed for 24/7 firm power
Land
337 sq mi
Cap. factor
35%
CO₂
Zero

Variable output. Raw count assumes same annual MWh; firm equivalent accounts for storage and geographic diversification needed for reliable power.

Natural gas
Natural gas combined cycle (600 MW)
Raw count (same annual MWh)
7
units needed
Land
210 acres
Cap. factor
55%
CO₂
7.9M tons/yr

Firm dispatchable. Emits ~800 lb CO₂/MWh.

Coal
Coal-fired plant (600 MW)
Raw count (same annual MWh)
8
units needed
Land
2.5 sq mi
Cap. factor
50%
CO₂
21.8M tons/yr

Firm. Highest CO₂ rate; significant air pollutants.

Capital cost bands

Wide bands reflect first-of-a-kind delivery uncertainty. Mid value from NREL ATB 2024; high band reflects delivered Vogtle / NuScale history. See methodology.

Advanced Microreactor (10 MWe representative)
microreactor · 252 units
$37.8B$55.4B$75.6B
Small SMR Module (77 MWe, NuScale-class)
smr · 32 units
$22.2B$37.0B$54.2B
Large SMR (300 MWe, BWRX-300 class)
smr · 9 units
$16.2B$21.6B$32.4B
Large Reactor (1,117 MWe, AP1000 class)
large reactor · 3 units
$23.5B$33.5B$50.3B

Data provenance

Demand basis
CA state per-capita × metro population (v2 methodology, 2025 basis year)
Demand period
historical state trend: 2001–2025
Population source
U.S. Census Vintage 2025 estimates
Reactor cost basis
NREL ATB 2024, with widened bands for FOAK uncertainty
Grid mix source
EPA eGRID 2023 (subregion CAMX)
Source comparisons
Hardcoded archetypes — see methodology page

These figures are screening-level scenario estimates. They are not forecasts, project proposals, or permitting determinations.