Travel Energy Intensity Comparator (2D)

Compare Mode

Trip Parameters

Trip distance 500 km

Vehicle load factor 70%

Grid renewable share (train) 35%

Selected: Short-haul flight

Energy per passenger-km

0.00 MJ/pkm

Total trip energy

0 MJ

Trip CO2 emissions

0 kg

Occupants on board

How it works

A vehicle's propulsion energy is set almost entirely by its own mass, speed and drag — the extra mass of a few more passengers barely changes it. So the energy cost per passenger is just the vehicle's energy split across however many people are actually on board:

E_pax = E_vehicle(km) x distance / N_occupants
N_occupants = round(capacity x load_factor)
CO2 = E_pax x distance x carbon_intensity(fuel or grid)

Each mode below shares one fixed "vehicle energy per km" (a short-haul jet, a mid-size car, a diesel coach, an electric multiple unit), taken from published transport energy-intensity studies (EEA/ICCT averages). The load factor slider changes how many seats are actually filled, which is the single biggest lever on the per-passenger number — the solo-car bar never benefits from it, since a lone driver stays at N=1 no matter how the slider moves. The grid renewable share slider only affects the electric train's carbon intensity, since electricity's CO2 depends on how it was generated, not on how much energy it took to move the train.

Mode buttons — pick which bar/curve/route drives the readouts on the left.
Distance — trip length in km; scales total energy and CO2 linearly, and sets how far the route strip's finish line sits.
Load factor — occupancy as a fraction of each vehicle's seat capacity (fixed at 1 for the solo car); the middle panel's curve is this same formula swept across the whole 20–100% range so you can see the shape of the payoff, not just one point on it.
Renewable share — fraction of the electricity grid powering the train that is carbon-free; drag the route panel to pan and watch the train's exhaust-cloud size shrink as the slider rises while the plane/car/bus clouds stay fixed (their CO2 factor is fuel, not grid mix).

Real-world relevance: this is exactly why filling seats (carpooling, high-occupancy trains and buses) cuts per-person emissions faster than almost any single vehicle-efficiency upgrade — and why the same electric train can be "green" or "not so green" purely depending on the grid behind the wall socket.

Flight Car (solo) Carpool Bus Electric train

drag route strip to pan →