Something like "Millenium" bars, or even a package of lifeboat rations from Mainstay or something similar would work to give you energy, and they won't require water, or heating. They will be good under virtually any weather conditions for about 5 years. I actually like the taste of the Milleniums, and they come in many flavors. You can find them in a lot of places, for example: Millenium Bars