Firewood is the original renewable fuel and still being utilized as the sole source of heat for roughly 1.5 million homes. Lately, an eco-friendly option to firewood has been introduced to the consumer under the brand name BioBrick.
If you are not familiar with BioBricks, they can be described as a two pound, 2″x4″x6″ brick created from compressed sawdust – just like wood pellets. The bricks are stackable, burn clean with much less than 1% ash, and expene about for a 1,900 pound pallet.
Although reading the homepage of BioBrick’s website I noticed an interesting statistic utilized to qualify the heat content. Here’s the heat claim quoted from their web site:
“One pallet of our BioBricks(TM) brings as much heat into your house as one cord of wood*.”
*(typical cordwood moisture content of 21%)
What got my attention was the 21% figure they supplied as the typical moisture content of cordwood. Any homeowner heating with wood knows that firewood isn’t regarded as seasoned unless the moisture content is 15% or much less.
Maybe the 6 points separating the two examples doesn’t sound like significantly, but wood with 21% moisture content is in fact 40% wetter than the 15% selection.
I don’t believe the BioBrick individuals were trying to intentionally mislead customers. It just sounds greater from a advertising and marketing stand point to say one pallet of BioBricks delivers the identical amount of heat as cordwood with 21% moisture content rather than a pallet of BioBricks delivers 94% of the heat of effectively seasoned cordwood.
But what happens when you compare the heat output of BioBricks with properly seasoned, 12% moisture cordwood?
For comparison purposes I’m going to use the Btu heat numbers from a table of “Wood Heating and Weight Values” published by the California Energy Commission. The table lists the weight and Btu values for 39 varieties of firewood at 12% moisture content.
Even so, a cord of firewood rarely consists of only 1 species which makes it challenging to accurately decide the Btu value. In order to even things out, I’ll compare the heat value of BioBricks to Ash. Ash is a middle of the road hardwood and, heat wise, is halfway among Live Oak and Western Red Cedar.
The heat value for a cord of 12% moisture Ash with an typical cord weight of 3,000 lbs is 25 million Btu’s. This works out to 8,333 Btu’s per pound.
The manufacturer’s heat estimate for a two pound BioBrick is 17,000 Btu’s, or 8,500 Btu’s per pound – nearly identical to Ash. (By the way, I picked Ash 1st and ran the numbers, not the other way around).
Even though my approaches are hardly scientific, I feel it would be fair to say the heat value of BioBricks closely approximates that of most firewood.