Print vs E-Reader: Energy Payback Crossover (2D)

An e-reader's manufacturing energy is spent once, up front; a printed book's production energy is spent again with every new copy. This simulator plays that trade-off out book by book on two synchronized 2D panels — a growing bar chart where one bar per printed book stands at a constant height next to a single tall device spike followed by nearly-flat e-book bars, and a cumulative-energy line graph tracing both running totals. Adjust the device's embodied energy, the per-book print energy, the per-book digital energy, and a reading pace, drag the chart to explore all 120 books, and watch the live crossover marker show exactly which book number — and roughly how many years of reading — it takes for the e-reader to pay back its own manufacturing footprint.