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

The Boston–Cambridge–Newton, MA-NH metro area is home to 5,034,221 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
5,034,221
Annual electricity demand
36,409,020 MWh
Primary state
MA
Today's grid mix
eGRID 2023 subregion NEWE — NPCC New England
56% Natural gas
largest source · 2023
Natural gas 55.9%
Nuclear 22.6%
Hydro 8.0%
Other 6.0%
Solar 3.6%
Wind 3.4%
Oil 0.4%
Coal 0.2%

Replacing the fossil portion (57% of generation) with nuclear would avoid roughly 5,546,996–9,103,739 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 NEWE. See methodology.

Annual electricity demand
MA state total — all sectors
-1.4%
2001 → 2025
025M50M75M100M200120052010201520202025

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
462
reactors needed
+ 6 more (visualization capped at 456 icons)
Small SMR Module (77 MWe, NuScale-class)
77 MWe per unit · 93% capacity factor
59
reactors needed
Large SMR (300 MWe, BWRX-300 class)
300 MWe per unit · 93% capacity factor
15
reactors needed
Large Reactor (1,117 MWe, AP1000 class)
1,117 MWe per unit · 93% capacity factor
5
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)
5
units needed
Land
6.5 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)
59
units needed
Land
3.2 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)
167
units needed ≈ 41.8M panels (≈400W each)
Firm equivalent (with storage)
418–668
units needed for 24/7 firm power ≈ 104.5M–167.0M panels (≈400W each)
Land
157 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)
4,959
units needed
Firm equivalent (with storage)
7,127–12,877
units needed for 24/7 firm power
Land
619 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)
13
units needed
Land
390 acres
Cap. factor
55%
CO₂
14.6M tons/yr

Firm dispatchable. Emits ~800 lb CO₂/MWh.

Coal
Coal-fired plant (600 MW)
Raw count (same annual MWh)
14
units needed
Land
4.4 sq mi
Cap. factor
50%
CO₂
40.0M 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 · 462 units
$69.3B$101.6B$138.6B
Small SMR Module (77 MWe, NuScale-class)
smr · 59 units
$40.9B$68.1B$99.9B
Large SMR (300 MWe, BWRX-300 class)
smr · 15 units
$27.0B$36.0B$54.0B
Large Reactor (1,117 MWe, AP1000 class)
large reactor · 5 units
$39.1B$55.9B$83.8B

Data provenance

Demand basis
MA 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 NEWE)
Source comparisons
Hardcoded archetypes — see methodology page

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