Light per kilogram: candles against oil lamps

Households that buy or make fuel for light face a simple question that is rarely answered in comparable units: how much light does a kilogram of fuel deliver? This paper computes total light delivered per kilogram for three sources — a tallow candle, a beeswax candle, and a simple open-wick oil lamp burning vegetable oil — from stated burn rates and stated luminous flux assumptions for each flame. The results are 1500.0 lumen-hours per kilogram for the tallow candle, 2000.0 lumen-hours per kilogram for the beeswax candle, and 3333.3 lumen-hours per kilogram for the oil lamp. For a stated evening of light, defined as 100 lumens of source flux for 4 hours, or 400.0 lumen-hours, the fuel required is 266.7 g of tallow candle, 200.0 g of beeswax candle, or 120.0 g of vegetable oil. The oil lamp leads because its larger flame produces more flux per gram burned, not because its fuel contains more energy. Its lead is not fragile: its assumed flux of 40.0 lumens would have to fall to 24.0 lumens, a drop of 40.0%, before it merely tied the beeswax candle. All results are calculations from stated assumptions. SIMULATED, NOT MEASURED.