Additional Math Pages & Resources

Thursday, July 1, 2010

We're all in hot water

Having hot water is one sign of civilization. We like the comfort of a hot shower, a hot bath, and a hot cup of coffee or tea. But since not everyone has this luxury we should be considerate in our energy usage.  I can't imagine an illustrated blog of saving hot water in the shower, so let's look at the cost of hot water for a daily cup of caffeine.



My friend Chris reports this from the UK:

REPORT
Got round to retrieving the energy reading do-dah from the lounge this morning and stuck it in-between the new variable-temp kettle and the socket. A bit rough and ready, I know.



We used .05 kilowatt/ hrs electricity to heat 400 ml of tap-temperature water to 100 C (boiling!) for black tea. We later used only .03 Kw/hr to heat the same amount of tap water to 80 C for green tea.

The .02 kwh difference we save is equal to 20 watt/hr. 


As we use 11w energy save bulbs for background lighting, this means that for every cup of green tea I drink (rather than black tea) we can light a bulb for nearly 2 hours for free!

Can we save the world by all drinking green tea?  Or perhaps even shift to white tea which only needs 65 degrees?



QUESTIONS
What do you think? Could we save the world? What would we need to know to decide?
  • How much tea do people drink?
  • How much energy is consumed heating the water?
  • What means are employed for boiling? ( electricity, gas, wood fire, etc.)

  • Can we measure the energy used boiling all the water? (different than the energy the water needs, because lots can be lost in the process)
  • Does it make any difference that Chris' voltage is 240 while ours is 110?

  • What efficiency gains could be attained in the boiling? (could we save energy)
  • Cost if we all move to the most efficient boiling process (tea kettle, microwaving a cup, etc.)
  • What gains could we get going to green tea? (Chris suggests 40% savings from his one test)
  • Is there an additional cost or savings in making green tea that we can add to the equation?
  • White tea is very rare; would there be enough if we all decided to start drinking it?

  • What would we do with all the extra energy saved?
  • How could we save the world with this energy?
  • What will I do with the white tea leaves because there is no strainer in the cup? 
           (I forgot to put it in while taking the photo!)

A. Sometimes MATH means knowing a question is too complex to be answered!