Propane powered landscape tools are showing up more frequently in the marketplace. Their manufacturers promote that facts that those tools are more powerful than electric and battery powered counterparts and are cleaner in the air than are the gas driven versions. They seem to be competitive price-wise.
The downside that we have heard are that these propane powered tools tend to be on the heavy side and not very attractive to women. The other problem is that the propane tanks are not refillable and must be recycled at a special place; not your garbage collector.