Travel Energy Intensity Comparator (2D)

Every trip has an energy bill, but that bill is almost never per-vehicle — it's per-seat-filled. This 2D comparator lines up five common ways to cover the same distance — a short-haul flight, a solo car, a carpooled car, a coach bus and an electric train — as an animated bar chart whose height tracks real published energy intensity in megajoules per passenger-kilometre. A second panel sweeps the load-factor formula across its whole range as a live curve so you can see the shape of the payoff, not just one point on it, while a third draggable route strip animates the selected mode's exhaust cloud shrinking or growing with the sliders. Move the load-factor slider and watch every shared-vehicle curve fall as more seats fill, while the solo car's flat line never budges; move the grid renewable-share slider and only the electric train's cloud responds, since its CO2 depends on what's powering the grid, not on how much energy it used.