Second, with this information you can calculate relative costs of the different fuels, at today's rates. For example, based on the current rate of natural gas from good ol' Duke Energy ($0.564), burning 308 CCUs (that's 308,000 cubic feet)-- the amount generated by a cord of hickory-- would cost $173; burning 150 CCUs of natural gas-- the amount generated by a cord of pine-- would cost $84. I couldn't quickly discover current rates of propane, but less than a year ago (11/2008) it was running about $2.30/gal in Toledo. 251 gallons x $2.30/gal. = $577. That ain't cheap.
If you are considering wood as a heating source, and thinking about its cost-effectiveness, you'd of course have to compare the price of wood with 'conventional' fuels. In an effort to get some idea, I stumbled upon Woodheat.org. Looks like a great fun place! Didn't find any pricing for average costs of wood in Ohio, but did learn a bunch.
I do believe I have rambled on. But hope you find the info useful in your preps.