I am brewing a batch of Hard Lemonade. The gravity started at 1.090 in mid September 2011. I pitched Lalvin EC-1118 as the yeast. It is now down to 1.029 and tastes good and is sweet. If I bottle and carbonate the traditional way, I will have bottle bombs. I don't own a keg or have the money to buy equipment for one. 

Is there a way I can carbonate a brew that doesn't involve either a keg or yeast? 

An alternative that I thought of if a commercial one doesn't exist:  

I have been considering experimenting and using the existing citric acid in the lemonade and adding baking soda (sodium bicarbonate). Hopefully they would react to create to create C02, but I am not entirely sure what it would do to the taste. It would be the same reaction that Alka Seltzer uses to carbonate water.