Boosting Candlelight with TEG Energy Recovery

You don’t need to be a physicist to understand that candles are inefficient as lighting. A massive portion of the energy they release through combustion goes to heat instead of light. Unless you’re trying to warm up the room at the same time, that heat is entirely waste energy. Maciej Nowak hates waste energy (I assume), which explains why he built this system to harvest candle warmth and turn it into light.

The goal here is to recapture the energy lost to heat and convert it into light that supplements the candlelight itself. At this scale, that seems a little silly, as this is a lot of effort, expense, and material to devote to a small amount of energy. But the same basic idea is used throughout industry where the losses are much more significant. They can’t eliminate all losses caused by unavoidable inefficiency, but energy recovery efforts are very often worthwhile.

In this case, Nowak achieved that using a small thermoelectric generator (TEG), which is really just a Peltier cooler running in reverse. A Peltier cooler uses electricity to move heat from one side of the unit to the other, resulting in cooling on the first side and heating on the second side. A TEG does the opposite and equalizes the temperature differential, producing electricity as it does.

Both Peltier coolers and TEGs are very inefficient. But since Nowak is recovering energy that would otherwise be lost entirely, they’re producing 100% profit — after you subtract the cost of the components, of course.

Nowak simply fabricated a massive heatsink to improve heat transfer, put the hot side of the TEG above the candle, and ran the TEG output to a DC-to-DC converter. That pushes low voltage from the TEG (around 1.8V) to a usable 3.3V to feed a pair of LEDs.

The energy recovery maxes out at around 0.4W, which isn’t much. At that rate, it will take about 14 years just to balance out the cost of the TEG alone.

But the light output from the LEDs actually seems to exceed that of the tea light candle. More than anything else, that demonstrates how inefficient candles are. However, it also shows a net lumen benefit and that means Nowak’s efforts were not in vain.