That question is a lot like asking “how long is a piece of string?” It depends.
A lot of us get our wood for free. But free wood is not unlimited. Labor is involved to char the wood. This makes comparisons difficult.
I highly doubt you’ll save money by burning charcoal vs utility power. Charcoal’s advantages are in it’s portability, independence, and ease of use. Not its cost.
When you buy them bulk you can get a nice wood pallet for at most around $100 per 1000kg. (nice round number )
Let’s assume labor is free or fully automated (i’m only interested in the practical efficiency of the charring / gasification / electricity generation process)
My goal isn’t to save money by burning charcoal vs utility power; my goal is just to see if it’s roughly in the same ballpark when it comes to utility power $/kWh & gather data to see how designs could be improved.
Hmm at the risk of sounding negative meaningful numbers are going to be hard to come by… I say that because most of us crazy enough to do this don’t factor in our time or the wood we use. More later…
David Baillie
I doubt that anyone would try to use engine grade charcoal to produce continuous power 24/7 and 365. Solar and wind with battery storage might work, and then use the charcoal powered generator for a short period of time if the battery needs supplemental charging. Perhaps you are referring to a wood gasifier because it makes charcoal during normal operation? Of course, the wood must be processed into small chunks and dried and stored, but it is less work than preparing the wood to be converted into charcoal, and then sorting, sizing, and storing it. Unless the charcoal is a by-product of cooking or heating, tremendous amounts of heat is wasted. (Referring to the two barrel or the cone kiln methods.) In my opinion, the light weight and compact charcoal gasifier unit is best used with small portable engines, or emergency power sources.
For large heavy duty continuous gasification projects, check out the gasification website at http://gasifiers.bioenergylists.org/
and Doug Williams site at http://www.fluidynenz.250x.com/
Hope this helps.
So kids are asleep now I type. What we are trying to say is that there are no two systems that are the same because none of us have the same reasons for doing this. So here are two example for you assuming free wood and labour.
Example 1 buy used genny barely big enough for next to nothing, use power tools all day, shut it off, go home. The Genny never pushes too hard so it lasts a lot of hours ;cost per kw very low but it’s an idealized setting of using everything you make and nothing else.
Example two: off grid home mostly solar tops up batteries on cloudy days, equalize batteries, runs during periods of high electrical demand. Since its part of the system that is built for 20 years the batteries are good and cared for,the inverter is sized for peaks so expensive, the genny you run will be bigger then you need to handle the vagaries of inverter charging. Cost per kw is high but it is a full 24/7 lifestyle.
Based on cost number one smokes number two but only because their goals are completely different.
So the question should be what is your true endgoal of the exercise?
As much as I like running engines on charcoal, it is hard to beat the price of utility delivered electricity at even 40 cents per kilowatt, As Dave and Ray mention, use solar as your primary generator and charcoal can back you up. Wait, maybe I can dig up some data I took last year on how much charcoal was use to produce so many Kw. I’ll look tomorrow.
Gary in PA
