Can someone give me a clue? Rocket stove pellet stove?

Hello
I m looking at  this wooden cabin in Sweden, i d love to have a rocket stove inside it. Would it be possible? Can anyone tell me if these existing heaters are worth anything? The owner says they re multifunctional: electricity, fuel or pellets. I d go for the latter but would like to know what you think and how i could convert this to a more eco friendly alternative?
Thank you
Look at the pictures!

Hello:

   Don't convert.

If you want to be able to heat the place in 2 years, (after the gas and the pellets cannot be found), then rocket mass heater is the correct way to go. Rockets run on sticks and/or split firewood only. Anything else messes up the exhaust system.

BUT, a traditional swedish stove is the forunner of the rocket type stove. Not as efficient but very close. AND

If you are in sweden there are tons of folks that know how to build traditional swedish  heaters.

Traditional swedish heaters are very clean burning.