In this blog I’ll be having some math fun (nerd alert!), showing you both how easily most of us unknowingly waste energy and how extremely efficient Aptera is. I’ll be figuring out the answer to the age old question:

“If you drink 3 cups of tea per day and always boil twice the water of what’s actually needed, how many Aptera miles would you have wasted in a year?”

### Experiment: How much energy is consumed by boiling water for one and two mugs

First up: one mug. After emptying my kettle and filling a mug with water, I transfered the water to the kettle and timed how long it took for the boiler to shut off. It took exactly 1 minute and 23 seconds.

After letting the kettle cool down for more than an hour, I’ve repeated the experiment with double the amount of water. This time it took 2 minutes and 23 seconds for the boiler to turn off. So the second mug only takes an additional 60 seconds. Not unsurprisingly, the kettle becomes more efficient when boiling more water. The heater only has to be heated once.

My kettle says 1400-1650W on the bottom. It’s a pretty dumb machine. It’s either on or off. My assumption is that its power consumption slightly changes based on the temperature of the heater. As you might know, electrical resistance over a wire increases with temperature. So let’s assume the kettle draws an average 1500W.

Using the power of extremely complicated math, we can now determine how much electrical energy was used for boiling the additional water for the second mug.

E = P * t

E = 1500W * 60s = 90,000 Joules = 0.025 kWh

### Calculated double check

Just to verify that my 12 year old kettle isn’t extremely inefficient or doesn’t run at its rated power, we can also calculate how much energy is needed to heat 250 cl (250 grams) of water from 20 to 100 degr Celcius (I’m not going to bother to do this calculation in Fahrenheit).

According to Wikipedia, the specific heat capacity of water is 4.18 J/(g*K). Multiplying this number with the weight (250g) and temperature difference (80K) yields the following minimum energy consumption:

E = 4.18 * 250 * 80 = 83,600 Joules.

Apparently, my 12 year old water boiler isn’t doing all that bad.

### Yearly result

Now, let’s take the realistic scenario in which you drink 3 cups a day and boil twice the amount of water (you know, just to be sure). This would lead to a yearly energy waste of:

E = 365 * 3 * 0.025 kWh = 27.4 kWh

Give the fact that Aptera can drive 10 miles (or 16 kilometers) on 1 kWh (read here how that’s possible), this means avoiding putting too much water in your kettle could earn you a trip of 274 miles, or 438 kilometers!

### Conclusion

Paris, here I come!

### Discussion

Of course, this only works if you actually own an Aptera. So use my referral link to reserve yours now ;-).

Thanks for reading!

Hey Seis, that’s pretty cool, gonna share with my tea drinking partner!

Hi Sies,

Leuke, interessante berekening. Ik herken dat teveel water verwarmen wel. Ik gebruik nog een ketel en tel dan tot vijf als de kraan loopt; dan heb ik precies een volle theepot. Maar die drink ik niet altijd leeg, dus toch teveel water gekookt 🤨 Dank voor je tip.

Frank uit Franeker