The creation of biochar via pyrolysis also produces bioenergy in the form of synthesis gas (often called 'syn-gas'). Such syn-gas contains a variety of gases which could be used to produce heat and power.
Interestingly when biochar and bioenergy are produced via pyrolysis it is a carbon-negative process (i.e. more carbon is consumed or captured than produced). This is because the organic materials being burnt are a normal part of the photosynthesis cycle, so when such carbon is taken out of the cycle by the biochar process there is an overall reduction in carbon in the atmosphere.
Also, due to biochar's high degree of stability, the carbon can remain 'captured' in soil for potentially many centuries. This means biochar is a simple way of 'sinking' carbon out of the atmosphere.
As hinted at with the way Amazonian's have used biochar it can be used as an excellent soil conditioner. Various studies have shown that adding biochar to agricultural soils can boost water and nutrient retention and crop yields, whilst lowering nitrous oxide emissions from fertilizers, by 50 to 80 percent!
Biochar can be used as a dietary supplement for animals, providing additional minerals, maintaining a healthy digestive system, reducing flatulence (which is a source of methane).
Biochar can also be used to reduce the smell of slurry and the ammonia emissions from slurry (ie. sweeten the dung). Plus the nutrients in the dung become closely mixed with the biochar, reducing the effort needed to mix the biochar with the soil
to make biochar right in your garden, start by digging a trench in a bed. Use a fork to loosen the soil in the bottom of the trench and you’ll get the added benefits of this “double-digging” technique.
Now pile brush and wood into the trench. Make sure its reasonably dry or it won't all burn as intended.
Now light the fire and watch. You want to have a fire that starts out hot, but is quickly slowed down by reducing the oxygen supply. You can tell what is going on by watching the smoke. The white smoke, produced early on, is mostly water vapor. Then as the smoke turns yellow, the resins and sugars in the material are being burned. But when the smoke thins and turns grayish blue, dampen down the fire by covering it with about an inch of soil to reduce the air supply, and leave it to smolder.
Once the organic matter has smoldered into charcoal chunks, use water to put out the fire.Well done, now you have biochar to use in your garden!
Once you get experienced with this technique, you can apply it to general pile burning by quickly adding additional material before the center 'burns out' and progressively starving the center of the fire of oxygen - then when you get to the gray smoke stage put the fire out with water.