Frankly, isn't boiling considerable amounts of water for hydroponics (to get it pathogen and bacteria free you need to boil it 15-20 minutes at least) a crackpot idea anyway?
And for the economic part of it, as I understood that was the actual argument, I have full understanding as even here in Thailand no-one would ever spoil a match nor light a fire for such purpose.
I don't know were it actually ranges, but Cambodia is one of the poorest countries worldwide. Now imagine an orphanage in such country, where they have to plan well to have enough cooking charcoal for the week. Even the less sharper knifes of the drawer should get the picture somewhat better now...and understand why they can't boil the needed amounts of water for their hydroponics.
