I have already mentioned one form of free storage: caching. That's when you find some isolated bushes somewhere nearby and hide you luggage there. If you choose a good location, the chance is low of anyone discovering your hidden cache.
But there's another method of free luggage storage when you are flying into a major airport: Simply don't claim your luggage when it arrives at the carousel! You can leave it there for a few hours, even for a day, and come back for it only when you are ready.
Leaving your bags at the airport might give you an opportunity to explore a new city and get situated there without having to lug your heavy bags with you. Alternatively, it could give you a chance to sleep in the airport, inside security if the secure zone at this airport is open all night. For example, if you arrive at an airport at midnight, you can remain in the main concourse and sleep there until morning, then exit security in the morning and claim your bags. (You can ask the gate agent meeting the flight if in fact the concourse is open all night.)
It happens all the time: Luggage arrives without its passenger. It's the opposite condition of a passenger arriving without his luggage. Both conditions happen a lot when flights are overbooked or there are a lot of stand-by passengers. After your bags circulate for a while on the carousel, they are removed by an airline employee and placed in or near the airline's Baggage Service Office (BSO) somewhere along the periphery of Baggage Claim. When you decide you want your bags again, you simply show up at the office and claim your bag.
In theory, the airline could charge you a storage fee, but in practice, no questions are usually asked. As long as you have your baggage claim check, the airline is happy to see the luggage go away. If anyone asks, you simply say you "forgot your bags," but it's unlikely anyone will.
There are a lot of caveats attached to this free storage service, and I wouldn't attempt it everywhere. Some considerations....
- Don't have anything in your checked luggage that you can't afford to lose. While the risk of theft is low, it probably increases when you abandon your bags like that. There's also a slim chance the staff might think the bag belongs somewhere else and forward it to another city.
- You can NOT use this storage method when coming off an international flight, since your bags have to clear customs at the same time you do.
- This storage method works best at airports where your airline has many flights. There, the BSO will be open longer hours, and your bag will be relatively insignificant. At smaller airports where your airline has only one or two flights a day, they are going to fret more about a lonely unclaimed bag.
- The BSO has to be open at the time you want to claim the bag. If there are no incoming flights at the time you want to claim your bag, the BSO may be closed, and you could have difficulty finding someone to released the bag to you.
- Don't leave your luggage unclaimed for more than a day. Your bag won't go away, but there's no telling where it might get locked up. After a day, most airlines start making serious attempts to reunite bags with owners, and you don't want to cause them too much hassle.
- Make sure your luggage is well marked with your name and phone number.
- If someone from the airline calls you about the bag (which is going to happen sooner or later) just tell them when you plan to come for it.
Security isn't a concern for bags that come OFF of airline flights, since they have already been screened going on. In spite of all the sinister airport announcements about "unattended baggage," no one at the airline will think the bag contains a bomb. They just want to get rid of the bag.
Keep in mind that when you fail to claim your bag, it is somebody's job to reunite you with it. These are some of the most abused customer service agents in the industry. ("Where the hell is my bag!") Don't make their job any more difficult than you need to. Come back for your bag as soon as you reasonably can, and try to give clear instructions if a BSO agent calls you (like "I'll be there by 2pm."). The BSO agents don't usually need an explanation; they just want to clear out the pit!