Hi! We are currently conducting a study on HTC of food waste(for undergraduate thesis) but we are having setbacks with regards to our methodology (specifically , equipments) as hydrochar production is kind of rare relative to biochar production. There is another university that produces biochar but we're not sure if we can use their equipent for hydrochar production. Thank you.
Hi Raisa Gerzon ,
hydrochar production is somewhat akin to an autoclave process and subcritical water gasification of biomass (Article Kinetic Analysis of Lignin Hydrothermal Conversion in Sub- a...
). The reactors used for biochar and HTC production are not the same.While proponents of the HTC process say that a main advantage is that wet biomass can be used thus saving the expensive drying step the water still needs to be heated, hydrochar separated from the aqueous mixture at the end of the process and dried. If the heat from the hot process water is not recovered for the next batch cycle I doubt that this process is energetically more efficient than pyrolysis with drying step. HTC is to my knowledge still by and large a batch process which limits it applicability at large scale. Then there is the issue of cost since the reactor must be designed to withstand relatively high pressure. When we look at the properties of the hydrochar its H/C ratio is in most cases >0.7 (
Article A comparative review of biochar and hydrochar in terms of pr...
; Figure 4) which means it does not fulfill the IBI definition of biochar and is prone to biodegradation. That means its ability to mitigate global warming by acting as carbon sink is very limited and it won't stay in soil for long. I would not recommend this technique to produce biochar.
Dear R. Gerzon,
Simple answer is No. The reactor for HTC is usually a high pressure, which makes it more expensive and complicated. However, it can be used to convert biomass (even high moisture feedstocks) at lower temperatures 150 -250 deg C than a conventional pyrolyzer. Hope this helps.
Regards, BBN
Hydrothermal carbonazation and Pyrolysis both having different mechanism so you cant produced biochar in HTC.
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