Charting the efficiencies of boiling water

Water takes a lot of energy to heat up. If you’d like evidence of this, simply jump into a 50° F swimming pool on Memorial Day. Despite the difficulty of heating water, that simple act accounts for a lot of industrial processes. From cooking a steak to running a nuclear reactor, there isn’t much that doesn’t involve heating water.

[Tom Murphy], Physics prof at UCSD decided to test out exactly how efficiently he could boil water. Armed with a gas stove, electric kettle, microwave, and a neat laser pointer/photodiode setup on his gas meter to measure consumption, he calculated exactly how much energy he was using to make a cup of tea.

The final numbers from [Tom]‘s experiment revealed that a gas stove – using a pot with and without a lid on large and small burners – was about 20% efficient. A gas-powered hot water heater was much better at 55% efficiency, but the microwave and electric kettle had a miserable efficiencies of around 15 and 25%, respectively. There is a reason for the terrible inefficiency of using electricity to heat water; if only the power from the wall is considered, the electric kettle put 80% of energy consumed directly into the water. Because the electricity has to come from somewhere, usually a fossil-fueled power plant that operates at around 30% efficiency, the electric kettle method of turning dinosaurs into hot water is only about 25% efficient.

The take-home from this is there’s a lot of power being wasted every time you run a bath, make some coffee, or wash the dishes. We would all do better by decreasing how much energy we use, much like [Tom]‘s efforts in using 5 times less power than his neighbor. Awesome job, [Tom].

War monument hacking


[Timo] tipped us off about a War Monument that has been… upgraded. The story starts when a monument was erected in Cherkassy, Ukraine to commemorate the ultimate sacrifice that was made by Russian soldiers during World War II. The huge statue and expansive plaza were capped off by an eternal flame. Unfortunately, when the Soviet Block broke up, the natural gas that had been provided by the government became a luxury so the flame was extinguished.

The eternal flame sat unlit, a sad commentary to the remembrance of the dead. But how to fix this issue? As cell phone companies came into the area, a need for cell phone towers arose. At some point a solution was reached; a cell phone tower was built in the bowl of the eternal flame and then wrapped with an LED marquee. The marquee now displays the image of a flame in perpetuity.

We’re not quite sure what to think about this. After some adjustment, the substitution of LEDs for flames will probably become accepted. The monument is now providing a useful purpose for the living, and once again shows a flame. We think that having something there showing that the memory is still alive is much better than the message an unkempt derelict sends.