They do use hydrogen for some weather balloons. It is also even more buoyant (slightly). On Fri, Mar 26, 2010 at 5:12 AM, Alan B Pearce wrote: >> Helium is very expensive. I once bough enough to fill three 1meter >> diameter balloons (total of about 1500 liters) and it cost about $25 >> US. Another $20 or so for the tank rental. I'm sure it can be had for >> around 1/10th the price if you are a high-volume industrial user but >> this guy isn't. > > In that case I would be tempted to use hydrogen ... > -- > http://www.piclist.com PIC/SX FAQ & list archive > View/change your membership options at > http://mailman.mit.edu/mailman/listinfo/piclist > -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist