I just discovered a powdered peanut butter in my local health food store: http://www.bellplantation.com/products/4-6-5-oz-jars-2-pack-pb2-2-pack-chocolate-pb2.html. It comes from the USA so it is not cheap but it would save a lot of weight. I was thinking it might come in handy for a week-long walk that I have planned.
I bought the PB2 with chocolate mix. You mix 2 tbsp of powder with 1tbsp of water and stir to 'rehydrate'. They were doing taste tests in the store and it seemed ok at the time though a very different texture from the crunchy peanut butter I normally buy. Has anyone else tried it before?