I've heard of the salt brine, or just packing the meat in barrels of salt. both are supposed to be very effective, but you need to rinse the meat off and I've heard they till are very salty. If you're looking for electricity-free preservation, I've heard of drying cooked ground
beef from the backpack chef website. The other way i can think of isn't electricity free to do, but the end result is. Freeze-drying. there are some home freeze-drying machines now, and I've heard nothing but good things from those that bought them. while it is
energy intensive, if you want really long lasting food it can't be beat.
A third option which is definitely not what you're looking for but still a viable strategy is to store the meat 'on the hoof'. most popular with families raising small animals like
chicken or
rabbits and utterly impossible for the bigger animals, the idea is you slaughter that morning and eat it all before it goes bad.
Smoking is another option but there seems to be a bit of back and forth about it in that truly effective curing seems to use some questionable materials. doing this also affects the meat taste (for the better, hopefully!)