Energy Return on Investment (EROI) Comparator

Energy Source

Controls

Plant scale (input, EJ-equiv) 3.0

Assumed plant lifetime 30 yr

Flow animation speed 1.0×

Live Readouts

EROI (E_out/E_in)—

Net energy gain—

Energy payback time—

How it works

Every power source must first spend energy to build and run itself — mining, manufacturing, construction, fuel processing, decommissioning — before it delivers any usable energy back to the grid. Energy Return on Investment is the ratio of lifetime energy delivered to lifetime energy invested:

EROI = E_out / E_in
Net energy = E_out − E_in = E_in · (EROI − 1)
Energy Payback Time ≈ plant lifetime / EROI

An EROI of 1 means a source barely breaks even — all the energy it produces is consumed just building and running it, leaving nothing for society. Historically fossil fuels and nuclear ran high (dozens to nearly a hundred), while today's best renewables (hydro, wind) are competitive and utility solar sits lower but keeps improving as panel manufacturing gets more efficient — a central quantitative argument in the energy transition debate.

Source buttons — switch between seven real generation technologies, each using a literature-representative EROI value.
Plant scale slider — sets the size of the input energy stream (E_in); net energy scales with it, EROI and payback time do not (they're ratios).
Lifetime slider — the assumed operating life used to convert the EROI ratio into a payback time in years.
The particle flow is literal: a fixed stream flows into the converter as invested energy, and a stream scaled by EROI flows out into the taller "output silo" — visually, a wide gap between the two towers means comparatively little net energy is left for the grid.

Figures are order-of-magnitude literature estimates (Hall, Murphy & others' EROI surveys) meant to illustrate the mechanism, not a single authoritative dataset — published EROI numbers vary by methodology and boundary assumptions.

Energy invested (E_in) Energy returned (E_out)

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