Biochar

Biochar is increasingly seen as a valuable product usable for a variety of purposes, which ranges from a filtration medium ("activated charcoal") to use as a soils supplement and more.  Compost is typically applied at comparatively shallow depth and has a low "fixed" carbon ratio, which means that compost gradually emits GHGs back to the atmosphere more readily than biochar.  Biochar is thus a more efficient option to sequester carbon.

Because feedstocks such as mixed municipal solid waste typically has a high carbon ratio, and has a high proportion of atmospheric carbon - potentially as much as 88% atmospheric carbon - Advanced Gasification with optimized biochar production, has the potential to be carbon negative.  In other words, Advanced Gasification in effect can extract carbon from the atmosphere and reduce GHGs, net of operations.  This makes it one of the few proven and viable options to economically sequester GHGs.

Biochar can also be obtained from pyrolysis-type systems, but the yield will typically be of lower quality than from Advanced Gasification, due to the lower temperature and latency differences in pyrolysis systems compared to Advanced Gasification.  This affects the biochar's potential use and value.  Although the yield varies depending on the feedstock type and nature, Advanced Gasification can potentially produce up to 30% by carbonic volume.  Our partners West Biofuels' biochar summary notes that high values are possible but this varies depending on feedstock.  Further information is available to clients on request.

Example

A 44-tonne RotoGasifier operating since 2014 in White Cross, Louisiana produces biochar from bagasse, a residual bi-product from sugar cane processing.  This sticky residue is difficult to process and other attempts had failed but the RotoGasifier succeeded, which is a testament to its robust flexibility in handling difficult feedstocks.  In this example the RotoGasifier's heat is captured and used to dry the sugar cane, thus reducing demand for natural gas and also, reducing GHGs. The biochar is sold by American Biocarbon.