Safe heating for the homeless?

Here is the situation - I help with feeding and suppling items for homeless in the city I live in, the problem is great, but I am looking for ideas on a safe way to help with heating. Some have propane heaters, those are costly to acquire for every person. And open flame is a dangerous option with fire wood and such. So any ideas on making propane attachments to the tanks to offer heat, or hand crank generators to store and then "plug" in a heater? The potbelly heater option is too risky also. So please offer constuctive ideas. And the "just send them to a shelter" is not helpful to me for this question. These are individuals that will not go to a shelter - some have tents, sheds, so this is what I am looking to help them with heating. Thanks for your time and ideas.