Operate like a ricecooker with solar batteries maybe. Maybe a plug in dealie, though. If you're urinating too much on this buffered tea, you will note your bones are melting out into the ocean and will probably have to supplement minerals. Liquid Potassium is the only safe way to get Potassium as the tablets don't break down. Practically every mineral imaginable is in raw vegie juice.
Magnesium affects heart strength.
Potassium is muscle strength. Magnesium tablets are cheap and easily available. You can even try alfalfa, seaweed tablets and do it that way. It needs other factors with it to be absorbed, though. Try Magnesium mixed with calcium and Vit D, a sure absorption formula.