For short term heat, put chameleon into a shoebox (he'll settle down after he's been in the dark for a while) and use a hot water bottle (your hot water tank will stay warm quite a while, or boil water on a BBQ) or use one of those chemical heat pads such as are used for shipping or keeping hands warm in gloves, or the salt(i think?) based ones in which you snap a metal disk and the liquid gets hot as it hardens, then you can reuse it after boiling.
Some emergency animal hospitals have generators to keep their buildings warm, and may allow emergency day care, for a fee.
Consider a little UPS to run a small watt lightbulb - just enough to keep him warm in a smaller cage covered with a blanket. I have several good UPSs that would each last a long time powering only a 10watt bulb. I bought them for my computers, but nevertheless.... But the batteries for these aren't cheap and do need replacing periodically (especially after several outages)
You can buy small human-powered generators - you pedal a bike to create current to run his heat light bulb or an electric blanket (this isnt as far fetched as you might think:
http://www.los-gatos.ca.us/davidbu/p...c_blanket.html or
http://www.econvergence.net/easy.htm)
Consider saving up for a generator if storms arent rare where you live.
Consider living somewhere with an alternate source of heat, such as propane or a wood fireplace.
The solar panel / wind turbine is a fabulous suggestion, if you've the $ for it.
Do not run camping stoves indoors if they were meant for outdoors.