Hello all, I'm new to the forum.

In many areas, storing enough petroleum based fuel for long term is tricky, illegal or against covenants (if they're discovered). One area I've been investigating is solar, retained heat cooking, or high efficiency methods.

Heat-retention/Fire-less cooking takes the food to the desired temperature, then puts it into insulation where the heat continues to cook without the further expenditure of potentially scarce fuel.
http://solarcooking.wikia.com/wiki/Heat-retention_cooking
http://solarcooking.org/heat%2Dretention/

Solar ovens, obviously use the sun to cook food. Most of these are a far cry from the elementary or jr. high science projects.
http://solarcooking.wikia.com/wiki/Main_Page
http://solarcooking.org/plans/

Another method I've been studying is the low-tech/high efficiency fire pit or stove from Aprovecho at http://www.aprovecho.org/web-content/publications/publications.html

They take the basic fire and make it much more efficient, thereby using less fuel. They have videos and printable instructions for making the Vita stove, a rocket stove, even a dung burning stove (hey, pioneers in the 19th century used buffalo chips!).

My 2 worth.