Saw this and wanted to share it:
http://homesteadsurvival.blogspot.com/2012/05/firewood-guide-btu-rating-chart-log.html
Type of Wood Heat Output Easy to Burn Easy to Split Heavy Smoke Sparks BTUs per Cord Rating
Ash Black Medium Yes Yes No No 19.1 Mil Excellent
Ash Green High Yes Yes No No 20.0 Excellent
Ash White High Yes Medium Np No 23.6 Excellent
Red Oak High Yes Yes No No 21.7 Excellent
White Oak High Yes Yes No No 26.5 Excellent
Live Oak High Yes Yes No No 25.0 Excellent
Beech High Yes Yes No No 21.8 Excellent
Beech Blue High Yes Yes No No 26.8 Excellent
Birch Black High Yes Yes No Medium 26.8 Excellent
Birch Grey High Yes Yes No Medium 20.3 Good
Birch Paper High Medium Medium Medium No 20.8 Fair
Birch White High Medium Medium Medium Medium 20.3 Good
Birch Yellow High Yes Yes No Medium 23.6 Excellant
Box Elder Medium Medium No Medium No 18.3 Fair
Buckeye Ohio Low Medium Medium No No 13.8 Fair
Butternut Low Medium Yes Medium No 14.5 Fair
Catalpa Low Medium No Medium No 15.5 Fair
Cedar Eastern Red Medium Medium Medium Medium Yes 17.1 Fair
Coffeetree Kentucky High Medium Medium No No 21.6 Good
Hickory Bitternut High Yes Yes No No 26.7 Excellent
Hickory Shagbark High Yes Medium No No 27.5 Excellent
Hard Maple High Yes Yes No No 29.7 Excellent
Pecan High Yes Yes No No Excellent
Dogwood High Yes Yes No No 24.3 Excellent
Soft Maple Medium Yes Yes No No 19.1 Good
Cherry Medium Yes Yes No No 18.5 Good
Black Cherry Medium Yes Yes No No 18.6 Good
Walnut Medium Yes Yes No No 20.3 Good
Elm American High Medium No Medium No 20.00 Fair
Elm Red High Medium Yes Medium No 21.6 Good
Elm Rock High Medium No Medium No 23.5 Good
Elm Siberian High Medium No Medium No 20.9 Fair
Hackberry High Yes Yes No No 21.2 Excellent
Sycamore Medium Medium No Medium No 18.5 Fair
Gum Black Medium Medium No Medium No 18.1 Fair
Gum Sweet Medium Medium Medium Medium Medium 18.7 Good
Mesquite High Medium No Medium No Good
Aspen Low Yes Yes Medium No 14.5 Fair
Basswood Low Yes Yes Medium No 12.6 Fair
Cottonwood Low Yes Yes Medium No 12.2 Fair
Chestnut Low Yes Yes Medium Yes Poor
Yellow Poplar Low Yes Yes Medium Yes 16.0 Poor
Southern Yellow Pine High Yes Yes Yes Yes Good
Douglas Fir High Yes Yes Yes Yes 21.4 Good
Cypress Medium Medium Yes Medium No Fair
Redwood Medium Medium Yes Medium No Fair
White Cedar Medium Yes Yes Medium Yes 17.5 Good
Western Red Cedar Medium Yes Yes Medium Yes 17.5 Good
Mulberry High Yes Yes Medium No 25.8 Excellent
Eastern Red Cedar Medium Yes Yes Medium Yes 17.5 Good
Juniper Medium Yes Yes Medium Yes Good
Piinon Medium Yes Yes Medium Yes Good
Eastern White Pine Low Medium Yes Medium No 15.8 Fair
Western White Pine Low Medium Yes Medium No 15.8 Fair
Sugar Pine Low Medium Yes Medium No 15.8 Fair
Ponderosa Pine Low Medium Yes Medium No 17.0 Fair
True Firs Low Medium Yes Medium No 19.5 Fair
Tamarack Medium Yes Yes Medium Yes 20.8 Fair
Larch Medium Yes Yes Medium Yes 20.8 Fair
Spruce Low Yes Yes Medium Yes 15.9 Poor
Alder Medium Fair Yes Medium Yes 17.6 Fair
Apple Medium No No Medium Few 17.6 Fair
Ironwood (Hornbeam) Very High Yes No No Few 24.7 Excellent
Black Locust Very High Yes No No No 26.5 Excellent
Honey Locust High Yes Medium No No 25.8 Excellent
Magnolia Medium Yes Yes No No 18.0 Fair
Madrone High No No No No 30.0 Excellent
Willow Low No Yes Fair Fair 14.5 Fair
Ratings are variable, moisture content effects results firewood should be well seasoned and dry for its optimum
BTU rating. Firewood is easier to split while it is still green.
Firewood with High or Very high heat output 1 cord = 21,000,000 - 24,000,000 BTU = 200-250 gal. of fuel oil or
250-300 cu. ft. of natural gas.
Firewood with Medium heat output 1 cord = 17,000,000 - 20,000,000 BTU = 150-200 gal. of fuel oil or 200-250 cu.
ft. of natural gas.
Firewood with Low heat output 1 cord = 12,000,000-17,000,000 BTU = 100-150 gal. of fuel oil or 200-250 cu. ft. of
natural gas.
Consider the cost of 1 cord of firewood vs the cost of fuel oil or the cu. ft. of natural gas. The cost of firewood is
usually more stable than the cost of fuel oils or gas and should prove to be a huge savings on your heating bill.Firewood Measurements1 cord measures 8 feet long, 4 feet high and 4 feet wide or 128 cubic feet
I think I'm going to go for some black locust on my next wood run 
