Energy Impact
Calculator

The one-sentence version for a class: every way of making clean electricity works, but they demand wildly different amounts of land, materials, storage, and time, and this tool lets students see those trade-offs for their own country or state.

Three classroom exercises, 10–15 minutes each.

1. The reliability trade. Set your country (or US state). Run "All solar," then "All nuclear." Compare the Storage & Firming section between the two. Discuss: why does one mix need batteries and overbuilding while the other needs none? What does the "Firm it" toggle change, and what does that tell you about the difference between energy and reliable power?

2. The land question. Run "80/20: renewables/nuclear," then "50/50," then "All nuclear," watching only the land section. The map comparison changes from countries to counties. Discuss: is land the right thing to minimize? Who decides what land gets used? Check the wind note — should we count the space between turbines?

3. What did France actually do? Pick your region, choose "Rebuild the entire grid," and use the France-style preset. France did roughly this between 1974 and 1990. Compare the build time shown to those 16 years. Then check the record-book table in Methodology: which country holds each record, and when? What do the dates tell you about whether the barrier is physics or politics?

Terms your students will hit: see the plain-language glossary in Methodology & sources below. Every number in this tool traces to a linked source there. Print any scenario as a one-pager with the button in the Share section.

Data as of July 2026. Electricity data: EI Statistical Review 2025 (full-year 2025). Built by Generation Atomic, a 501(c)(3) growing the movement for the atomic energy of today and tomorrow. Questions or corrections: gena@generationatomic.org.

Electricity data: Energy Institute Statistical Review of World Energy (2025 generation by fuel, by country). Non-electric fossil energy is each region's oil, gas, and coal consumption minus the share burned in power plants, from the same source.

Nuclear land & multi-unit sites: The 0.3 km²/TWh/yr nuclear figure reflects the fenced plant site from operating stations, not the wider emergency planning zone (EPZ), which is a regulatory radius, not occupied land — people live, farm, and work inside EPZs today. Because a reactor's site scales sublinearly with capacity, multi-unit stations use dramatically less land per TWh than single units: siting four reactors together barely enlarges the footprint of one. Real fleets cluster units, so the effective number is often below this already-small figure.

Land: Land-use intensity of real operating sites from Lovering, Swain, Blomqvist & Hernandez (2022), PLOS ONE, in km² per TWh per year: nuclear 0.3, onshore wind 0.4 direct (99 with full project spacing), utility solar 19, hydro 14, geothermal 1.4, gas w/ CCS 1.3. Biomass defaults to dedicated energy crops at 580 km²/TWh/yr, the honest figure for biomass scaled as a grid resource, since Lovering finds dedicated biomass is the single most land-hungry source (up to 58,000 ha/TWh/yr, four orders of magnitude above nuclear). Switching the feedstock to waste and residue in Advanced drops it to 0.15, because burning leftovers claims no dedicated land.

Materials: Tonnes per GWh of lifetime generation, anchored to US DOE Quadrennial Technology Review (2015) as updated by Wang et al., Breakthrough Institute (2023). Fleet build mass = intensity × annual generation × plant lifetime (nuclear 60 yr, hydro 90, solar 25, wind 20, geothermal 30, biomass and gas 25). Uranium fuel shown as annual demand versus world mine production.

Breeder reactors & uranium supply: The default once-through fuel cycle uses only the ~0.7% of natural uranium that is U-235. Fast breeder reactors convert the abundant U-238 into fuel, extracting on the order of 60× more energy per tonne mined and able to run down existing spent-fuel and depleted-uranium stockpiles; the tool cuts uranium demand accordingly and raises nuclear capital cost about 20%. Breeders work (Russia's BN-800 runs commercially) but have a thin and costly track record (France's Superphénix, the US IFR), so treat the option as a what-if, not a deployed baseline. Separately, uranium from seawater has been demonstrated at laboratory scale and would make the resource effectively limitless; its higher extraction cost (~$400–1,000/kg versus roughly $130 today) barely moves the delivered electricity price because fuel is a small share of nuclear's cost. Both are off by default.

Carbon: Lifecycle medians, g CO₂/kWh: nuclear 6 (UNECE 2021), wind 14, solar 29, hydro 15, geothermal 19, gas w/ CCS 130, unabated gas 490, coal 820, oil 650 (IPCC AR5 / UNECE). Biomass defaults to 230, the IPCC AR5 lifecycle median that reflects dedicated-crop cultivation, fertilizer N₂O, and land-use change; switching to waste and residue feedstock in Advanced drops it to 34. Biomass carbon is genuinely contested, and counting it as low-carbon at all assumes the harvested carbon regrows, which can take decades.

Build pace: Each technology builds at the fastest 5-year national pace on record: the largest 5-year jump in annual generation, divided across those five years, per person at the time (period population — measuring the achievement as it happened), recomputed from EI Statistical Review 2025 data through 2025, countries ≥5M people, with 3-year smoothing on hydro and biomass to remove rainfall noise. These match the Radiant Energy Group's published records from the same source. Because pace is per-capita, bigger regions automatically get proportionally bigger workforces; the Advanced mobilization setting scales ×0.5–×3. Technologies build in parallel; "years to build" is the slowest lane. The record book:

Technology	Record pace	Set by
Nuclear	770	Sweden, 1981–86
Wind	535	Finland, 2019–24
Hydro	490	Canada, 1968–73
Solar	250	Australia, 2018–23
Biomass	230	Finland, 1988–93
Geothermal	100	New Zealand, ~2012
Gas + CCS	250	proxy (no CCS record exists)

Record pace is kWh per person per year of new generation added, at the fastest 5-year national buildout on record. Close runners-up, same measure: nuclear — UAE 710, France 575; wind — Norway 438, Sweden 389; solar — UAE 252, Netherlands 183; hydro — Sweden 379.

Beyond the grid: Fossil fuel burned outside the power sector (transport, heat, industry — measured here as fuel energy) is replaced two ways. A share (default 50%, adjustable) is directly electrified. Electricity delivers the same service on far less energy because it skips combustion's heat-engine losses: an EV uses roughly 30% of the fuel energy a petrol car burns, a heat pump about 30% of a furnace's. The tool captures this with a service-efficiency factor (default 0.40× across a mixed set of end uses; selectable down to 0.30× for transport-and-heat-heavy regions or up to 0.55× for heavy industry, where high-temperature process heat gains little from electrification). This is the same efficiency credit Lazard and others apply when comparing electric to combustion end uses — and it is why direct electrification, wherever it is possible, beats making synthetic fuel. The remaining share becomes synfuels: fuel energy ÷ power-to-fuel efficiency (default 45%; published power-to-liquid chains run 40–50%, ICCT models ~52%, pure hydrogen 65–70%). Two honest caveats a critic will raise: high-temp industrial heat and some heavy transport are genuinely hard to electrify, which is what the adjustable industrial setting is for; and wind and solar, being electricity already, never pay a heat-to-electricity conversion at all — their advantage over thermal generation on this front is real and is reflected in the fact that every clean source here is counted by delivered electricity, not fuel-energy-in.

Jobs: Operations jobs per MW are literature-anchored estimates in the tradition of Rutovitz, Dominish & Downes (2015, for Greenpeace/ISF), the most widely-cited global source for energy employment factors. The nuclear figure (0.7 jobs/MW, generation plus fuel cycle) reproduces the US Energy & Employment Report 2025's actual combined total for nuclear generation and fuel (67,900 jobs) applied to the current US fleet almost exactly — the closest independent check available. Solar and wind use lower permanent-operations factors than some advocacy sources cite, because utility-scale plants need very little ongoing staff once built: a large solar farm runs with a handful of technicians, so its permanent employment per unit of energy is well below nuclear's (this tool shows roughly 35 permanent jobs per TWh for solar and 55 for wind, against about 90 for nuclear). Most solar and wind employment is one-time construction and manufacturing, which is counted separately as job-years, not permanent jobs. The other technologies' factors follow the same literature but haven't each been re-verified against USEER line items; treat them as reasonable estimates. Construction and manufacturing job-years per MW built come from the same source family.

Ending energy poverty: When enabled, the build is sized so every person in the region reaches a target annual electricity use. The world today averages roughly 4,000 kWh per person per year, but that hides enormous inequality: North Americans use about 12,400, Europeans about 6,000, and much of the global South only a few hundred. Targets offered: a "modern decent living" floor (3,500 kWh, in the spirit of the Rockefeller Foundation's Modern Energy Minimum and related decent-living-standard work), the European level (6,000 kWh, a developed standard without North America's air-conditioning and large-home intensity), and the US level (12,385 kWh). The uplift is added to the clean build target on top of any demand-growth multiplier; regions already above the target see no change. This is the honest scale of the climate-and-development problem together: decarbonizing while also lifting billions out of energy poverty is a far bigger build than decarbonizing today's grid alone.

Demand growth: Optional demand multipliers size the build for the future grid, not today's: +45% matches the IEA World Energy Outlook 2025 projection of 40–50% global electricity demand growth to 2035 (AI, data centres, electrification); ×2 and ×2.5 are full-electrification scenarios to mid-century. Growth is added to the electric build target; the synfuel target stays tied to today's fuel use.

Capital cost: Overnight costs per kW from the EIA/Sargent & Lundy Capital Cost and Performance Characteristics report (2025-2026 vintage) and the AEO2026 Electricity Market Module assumptions. Wind $1,500/kW and solar $1,400/kW match EIA's current modeling inputs. Nuclear defaults to the DOE Pathways to Commercial Liftoff Nth-of-a-kind cost ($3,600/kW after 10–20 deployments of a standard design; the same report puts a well-executed first-of-a-kind at $6,200/kW and NOAK AP1000s at $4,700/kW). Advanced offers the actual Vogtle 3&4 cost ($15,700/kW), DOE's projected fourth AP1000 ($6,200/kW), the Barakah turnkey price (~$4,300/kW), and domestic Chinese (~$2,800/kW, Hualong One) and Korean (~$2,300/kW, APR1400) builds — the proven costs where nuclear construction never stopped. Solar and wind get parallel options: US EIA inputs (default), IRENA global weighted averages (~$800 and ~$1,150/kW), and lowest-market costs. Rooftop solar automatically switches to ~$2,700/kW (NREL residential/commercial blend) and offshore wind to ~$4,000/kW with a 45% capacity factor and no land footprint. Gas + CCS uses EIA/Sargent & Lundy's combined-cycle with 90% carbon capture (~$3,000/kW); note no such plant runs commercially at scale, so treat it as an engineering estimate rather than a market price. Investment figures are overnight capital only — no financing, fuel, or operating costs.

Firm grids and storage: Above ~70% firm share, a grid still has to meet a daily demand swing, and there are two real ways to do it. It can load-follow, throttling reactors down at night so the fleet's capacity factor falls and more nameplate is built to cover peaks (France does this). Or it can run the plants flat-out and store the surplus, banking cheap overnight output and returning it at the peak, which is precisely why several pumped-hydro stations were built alongside nuclear plants in the 1970s and 80s. This tool costs both paths and, by default, picks the cheaper for the scenario (override in Advanced). Storing the surplus keeps nuclear's capacity factor high and usually shortens the build. Crucially, a firm grid needs only a daily shift of a few hours, an order of magnitude less storage than a wind-and-solar grid, which must ride out multi-day weather droughts. Storage, in other words, helps nuclear too; it just needs far less of it.

Storage & firming: When "Firm it" is on, battery storage and wind/solar overbuild scale with the variable share of delivered power, interpolated between anchor points from Shaner, Davis, Lewis & Caldeira (2018, Energy & Environmental Science): wind and solar serve demand roughly linearly up to ~80% of hours, reaching 80% takes about 12 hours of storage, and beyond that the storage or overbuild requirement rises steeply — several weeks of storage at 100%. Overbuild anchors also draw on Sepulveda, Jenkins, de Sisternes & Lester (2018) on firm low-carbon resources. The storage figure is total energy capacity of any duration mix — hours of load-shifting at moderate shares, growing into multi-day reserves as the variable share rises. It does not separately model a worst-case multi-week European-style Dunkelflaute; overbuild covers part of that risk, and real systems would add transmission and demand response this model omits. Battery cost defaults to $300/kWh installed (NREL 2025 utility-scale 4-hour benchmark ≈ $334/kWh; leading projects ≈ $125–150). Synfuel electricity is treated as flexible demand that needs no firming. This is a deliberate simplification of a genuinely hard modeling problem — real systems trade storage, overbuild, transmission, and demand response against each other — but the shape of the curve is what the literature agrees on: the last 20% is where the cost lives.

Pay & public revenue: Wages anchored to BLS OEWS May 2024 medians (nuclear reactor operators $123,380, nuclear technicians $104,240, power plant operators $103,600, wind techs $62,580, solar installers $51,860); each technology gets a plant-wide average. Tax estimate is deliberately rough: 25% of payroll (combined income and payroll taxes) plus 0.5% of capital cost per year as a property-tax proxy — consistent with reported single-plant figures like nuclear stations paying tens of millions a year to local counties.

Lives saved: Mortality per TWh from Our World in Data (Ritchie), building on Markandya & Wilkinson (2007, The Lancet) and Sovacool et al.: coal 24.6 deaths/TWh, oil 18.4, gas 2.8, biomass 4.6, hydro 1.3, wind 0.04, nuclear 0.03, solar 0.02. Note the nuclear figure includes Chernobyl and Fukushima, where nearly all deaths came from the evacuation — a policy decision — rather than radiation, so 0.03 is conservative against nuclear. Synfuel scenarios credit displaced non-electric fuels at a blended 12 deaths per thermal TWh.

Flexibility, both directions: Wind and solar above ~30% of delivered power pay in storage and overbuild (see above). Nuclear and geothermal above ~70% pay too: reactors must load-follow, France-style, so fleet capacity factor slides from 90% toward the grid's load factor (~62% at 100% share), and the extra capacity to cover peaks is built and counted. Synfuels lift the penalty for everyone — flexible electrolysis absorbs the off-peak power. No technology gets a free pass on the shape of demand.

SMR & microreactor economics: Switching reactor size also switches the capital-cost menu, because small reactors sacrifice the economies of scale that make large plants cheaper per kW. The evidence so far is sobering: NuScale's cancelled Idaho project reached roughly $21,600/kW, higher per kW than Vogtle. Vendor NOAK targets are lower (IEA 2025 puts EU SMRs near $10,000/kW; independent bottom-up work by Asuega et al. 2023 spans $4,300–6,400/kW), and the tool offers that full range with a mid-estimate default. Microreactors are costlier and more speculative still, with credible figures from about $6,700/kW (Oklo's NRC filing) up to $25,000/kW. The theory that factory production drives costs down is sound but unproven; only three SMRs were operating worldwide as of 2024, too few to show the learning effects proponents expect. Treat every small-reactor cost here as a scenario input, not a market price.

SMR land: Selecting SMRs or microreactors also shrinks the fenced-site land per unit (×0.5 and ×0.3 of the large-reactor figure), reflecting the smaller emergency planning zones these designs pursue on the strength of passive safety, smaller radioactive source terms, and below-grade siting. The direction is what vendors and the NRC's SMR emergency-planning rulemaking point toward; the exact factors are illustrative, not certified, since few of these plants are built and licensed yet.

SMR materials: Large-reactor material intensities are the default. Selecting SMRs applies ×1.6 to structural materials and microreactors ×3, reflecting the surface-to-volume penalty of small cores (direction supported by Krall, Macfarlane & Ewing 2022, PNAS, and UC Berkeley's per-MW commodity comparisons), with genuinely large error bars — some designs like the BWRX-300 target less concrete per MW than large plants. Fuel scales with generation, not with the multiplier.

Fossil jobs displaced: ~127 jobs per TWh of fossil electricity displaced (USEER 2025 generation jobs plus the power-sector share of coal, gas, and oil fuel-supply jobs, divided by US fossil generation) and ~38 jobs per thermal TWh of non-electric fossil fuel displaced by synfuels. US-derived factors applied globally as a rough proxy. Synfuel-plant jobs created are not counted, so the net-jobs figure is conservative for synfuel scenarios.

Plain-language glossary: A TWh (terawatt-hour) is a billion kWh — enough electricity for about 90,000 US homes for a year. Capacity factor is the share of the time a plant effectively runs at full power (nuclear ~90%, solar ~20%). Overbuild means building more wind and solar than demand needs so there's enough on weak days; the surplus on good days is curtailed (thrown away). Firming is everything that turns variable power into reliable power: storage, overbuild, flexible demand. Load-following is a plant ramping down when demand drops — France's reactors do it nightly. Overnight cost is construction cost excluding financing, as if built overnight. NOAK (Nth-of-a-kind) is the cost after a design has been built enough times to get good at it. gCO₂/kWh measures how dirty each unit of electricity is, over the full life cycle.

Build pace in small export regions: The build-time metric divides the job by a region's own population, using the fastest per-person build any nation has achieved. That works for countries and self-contained grids, but it distorts small-population energy exporters: Wyoming generates roughly 69,000 kWh per resident, over five times the US average, because it ships coal power to other states. Paced against its ~590,000 residents, replacing that output looks like it takes generations. The number is honest arithmetic but the framing is wrong for an exporter; in reality neighboring states, which consume that power, would build alongside it. There's no clean per-region fix without labor-force and trade data the tool doesn't carry, so the results flag it in plain language instead.

Generation, not consumption: Every figure here is built on electricity generated inside a region, not electricity consumed there. Regions that import much of their power look small: the District of Columbia generates almost nothing because it buys nearly all its electricity from neighboring states, and any net importer shows a grid smaller than what it actually uses. The model asks what it would take to build clean generation equal to what a region produces from fossil fuels today, which is the honest question for a builder. Cross-border imports and exports, and the transmission that carries them, are not modeled.

Nuclear operating life: Replacement rates assume plants run 60 years before rebuild (the common US license-renewal term), adjustable from 40 up to 100 in Advanced. Reactors are increasingly cleared for 80-year operation, which roughly halves the long-run replacement pace versus a 40-year assumption. Wind and solar are held at about 22 years and other technologies at their own service lives; those are not yet user-adjustable, since nuclear longevity is the figure most often disputed.

The 50/50 \u201cOntario-style\u201d preset mirrors the grid Ontario actually runs: roughly half nuclear, about a quarter hydro, and the rest wind, solar, and a little biomass, with no geothermal. Ontario decarbonized to over 90% clean and phased out coal entirely by 2014, largely on the strength of its CANDU reactor fleet.

The Low-land 50/50 preset keeps nuclear at half but leans the rest on the most land-efficient firm sources, geothermal and hydro, with only a modest slice of wind and solar. It shows how a grid built to minimize its physical footprint looks: nearly all firm generation, very little storage, and a fraction of the land a variable-heavy mix would occupy. Both geothermal and hydro are geographically constrained, though: geothermal depends on the right geology or on advances in enhanced geothermal, and hydro is capped by a country's rivers and rainfall. The tool flags when a scenario's hydro exceeds what the selected region could physically build.

Hydro potential ceiling: Because hydro cannot simply be scaled up anywhere the way solar panels or reactors can, the tool checks each scenario's hydro against a per-country feasibility ceiling: the sum of a nation's existing hydro generation plus its remaining economically feasible potential (from Gernaat et al., Nature Energy 2017, a high-resolution assessment of 3.8 million potential sites, cross-checked against IHA and IEA current-generation figures). When a mix asks for more hydro than that ceiling allows, a warning appears in the results. The ceiling is a physical-and-economic limit, not an environmental endorsement; many feasible sites carry serious ecological and displacement costs. For US states, where essentially all economic hydro is already built, the ceiling is each state's current hydro plus roughly 50% for turbine uprates and powering existing non-powered dams (DOE/ORNL put the remaining economic potential far below the larger technical figure). One thing the tool does not model: hydro's seasonal and drought variability. Real hydro output swings with rainfall and snowmelt, and dry years (recent examples in Brazil, Zambia, and China) have forced grids back onto fossil backup. The tool treats hydro as steady annual generation, so it modestly overstates hydro's firmness in drought-prone regions.

The Study-consensus 2050 preset (the default) reflects the central range of US deep-decarbonization studies (Princeton Net-Zero America; NREL's 100% Clean Electricity by 2035; MIT/Sepulveda et al.): solar and wind carry most energy, firm resources — nuclear, geothermal, hydro, a little gas with capture — carry reliability. The all-nuclear, all-solar, and all-wind presets are bounding thought experiments, not proposals; they exist to show where the edges are.

What this model leaves out: Transmission. Every scenario would need new wires — more for remote wind and solar, less for plants sited at retiring fossil sites — and this tool prices none of them, for any technology. Grid operating costs, financing costs, and fuel costs (beyond uranium tonnage) are also excluded; the investment figure is overnight capital only.

US states: Generation by fuel from EIA-923 2024 final data (utility-scale plants; small-scale rooftop solar, about 75 TWh nationally, is not included). Populations from Census Bureau 2024 estimates. Non-electric fossil energy is apportioned from the national total by population share, an approximation — energy-heavy industrial states burn more than their share.

Where the thumb could be — read this before arguing with the results: Defaults that favor nuclear: costs assume Nth-of-a-kind AP1000s ($4,700/kW), not the first-of-a-kind reality; build paces are all-time records; wind is counted at full project area while nuclear's exclusion zone is not counted. Defaults that work against nuclear: the mortality rate includes Chernobyl and the Fukushima evacuation; reactors above 70% grid share pay a load-following capacity penalty; uranium is assumed 100% freshly mined, no recycling. Every one of these is one click away from its opposite in Advanced. That's the point.

Every constant lives in one labeled block at the top of this file's script, so numbers are easy to audit and update.