separation and pyrolysis of fermentation residues replaces expensive storage and logistics and generates additional revenue
Biogas plants must be able to store their digestate for 180 or 270 days. If the digestate storage is full and spreading is not permitted or possible due to the weather, the plant must be throttled in the worst case.
In addition, in red areas it is often not possible to spread the entire fermentation residues on the fields in the region, but they have to be transported to other regions at great expense.
Biowaste and food waste digestion plants also have digestate that requires energy-intensive hygienization before transport and is contaminated with plastic and microplastics.
The fermentation residues of a biogas plant can be pressed off via a separator and thus separated into a solid and a liquid phase. The solid phase is further dried with waste heat and processed in an autarkize plant into energy-rich pyrolysis gas and biochar.
Thanks to the unique process, the pyrolysis gas of the autarkize plants has a similar energy density as the gas of the biogas plant. It can therefore be fed directly into the digester via a simple pipe connection and mixes with the biogas there. This not only results in a higher gas volume. The added pyrolysis gas also leads to a positive shift in the C-N ratio and thus to a higher methane yield in the fermenter.
In this way significantly more energy was obtained by fermentation and subsequent pyrolysis of the same amount of input material (e.g. renewable raw materials) and later mixing of the gases. A 15-20% increase in power is common. This increase in output also allows the reduction of grown or purchased quantities for the same yield. At the same time, this process reduces the need for digestate storage. This means that fermentation residues from other plants can also be added. Any necessary hygienization is unnecessary due to the temperatures of 500-750 °C in autarkize plants.
These temperatures also recycle plastics and microplastics without residue. The resulting biochar can be used on the farm as a soil conditioner or marketed. Additional revenues can be generated through the sale of CO2 certificates (CDR credits).
Storage, disposal and logistics problems thus become sustainable solutions and revenues.
your added value
pyrolysis gas production and utilization in the fermenter
The unique autarkize process enables the recovery of an energy-rich pyrolysis gas from solid fermentation residues. As it has a similar calorific value and properties to biogas, it can be mixed with biogas without any problems and utilized in the CHP unit of the biogas plant. The costs for an additional CHP unit are thus avoided.
The pyrolysis gas essentially consists of methane, hydrogen, carbon monoxide and carbon dioxide. When mixed with the biogas in the digester, it dilutes the ammonia that is regularly present there. Since too much ammonia inhibits microbiology, conversely, diluting ammonia leads to better methane yield.
In total, the operator of a biogas plant receives more usable gas through the pyrolysis gas and also through a higher methane yield.
use the produced biochar yourself or market it as a soil conditioner and fertilizer
Biochar produced in the process meets the high standards for use in agriculture, viticulture and fruit growing, as well as in horticulture and landscaping. This results in a wide range of opportunities for biogas plant operators.
On the one hand, they can ferment the biochar together with the liquid fermentation residues on site. This produces a biochar activated with nutrients and microorganisms that can be used in their own cultivated areas to improve the soil, microbiology and nutrient supply to the plants. In contrast to the application of the untreated, liquid fermentation residues, the biochar activated in this way has a higher nutrient efficiency (depot fertilizer) and actively contributes to humus formation.
Biochar that is not used by the company itself can be sold to other companies, private individuals or larger substrate manufacturers.
sale of CDR credits
Biochar from autarkize plants is not only a valuable soil conditioner but also a permanent carbon sink. Plants extract CO2 from the atmosphere as they grow and use the carbon to build their cells and structures. Normally, this carbon sequestered in the plant is turned back into CO2 by rotting or burning. The autarkize process, however, converts a larger portion of the carbon into a stable biochar. If this carbon is then introduced into soils, for example, it can hardly be decomposed and the CO2 once bound remains permanently removed from the atmosphere.
Each autarkize plant removes several thousand tons of CO2 from the atmosphere every year. For this immensely important contribution to climate protection, producers and users of autarkize biochar can obtain certificates. The so-called Carbon Dioxide Removal (CDR) credits are issued in quality-assured processes and are purchased by companies and private individuals, e.g. on international stock exchanges.
The CDR certificates not only indicate what an important contribution to climate protection farmers and biogas plant operators can make. They are also a good, additional revenue stream and offer companies and private individuals the opportunity to offset their partially unavoidable greenhouse gas emissions locally in domestic cultivation areas.
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