Biomass beneficiation solution: Vuthisa Biochar Retort
The basic Vuthisa Biochar Retort (Kiln Kit) consists of:
- 4 Main kiln side sections bolted together with 64 x bolt/nut/spring washer assemblies and 128 washers.
- 4 x Channel Iron air inlets
- 2 x Collars
- 1 x Heavy Duty Rounded Flat Lid with Chimney Flange
- 3 x Open top reconditioned Heavy Duty 55 Gal Barrels and Lids
- 1 x Clamp & choker chain set
- 1 x Top Cap
- 1 x Chimney
- 1 x 5L Etching High Temp Paint/Primer.
- 3 x Timber Spars – 4.8 m x 10 cm (last 0.5 m tapered)
- 1 x Block and Tackle Hoist – Double Purchase
- 1 x Loose Rope – 3 m
- 1 x Snatch Block with Rope Grommet
- 1 x Hoist Rope – 6 m
- 1 x Rope Grommet for attachment to Block and Tackle
- 1 x Snatch Hook for hooking drum/barrel handle
Vuthisa Technologies developed Energy Efficient (EE) Emission Reducing (ER) kilns. This innovation is significant in two ways. Firstly, biomass left in-field following harvesting operations emits large quantities of methane and other non-CO2 gases that contribute to global warming due to aerobic digestion. Secondly, the kilns have an after burning technique that reduces the emission of greenhouse gasses by about 80% when compared to open fire or kilns without an after burning system. This was researched by an independent party, Airshed.
What is Biochar? Biochar can be distinguished from charcoal—used mainly as a fuel—in that a primary application is used as a soil amendment (organic fertiliser) with the intention to improve soil functions and to reduce emissions from biomass that would otherwise naturally degrade to greenhouse gases. The Vuthisa retort can also produce charcoal and charcoal fines, but made in a more environmentally friendly manner. The use of the word Biochar in this write-up also refers to charcoal produced in the Vuthisa kiln.
The resultant biochar from renewable biomass is not only a carbon sink but offers benefits in terms of retaining moisture & nutrients and providing habitat for good microorganisms, especially mycorrhizae. There is a great need to move away from fossil energy dependent processes for manufacturing fertilisers. It takes about as much energy to make the nitrogen fertilizer for an acre of corn (150 lbs) as it takes to drive a car 600 miles, because it is made using natural gas and other chemical processes that require energy. Our biochar production process only requires fossil fuel to execute short-hauling and transportation activities of the end product, which will not contain any chemical constituents.
Alternative types of kilns like the “earth kiln” and the “brick and/or cement kilns“ have prohibitive disadvantages for making charcoal and therefore biochar. The earth kiln is very labour intensive and besides that, it pollutes much more as there is no after-burning mechanism or the capability to produce biochar in a bonafide retort system. The brick or cement kilns are relatively expensive, take significant time to construct and are also permanent structures. The Vuthisa kilns are portable. They can be flat-packed and exported and assembled on site and due to their circular design can be repositioned by rolling it.
Greenhouse gasses are only reduced if the correct kiln is used. In 2001, Pennise et al. conducted research on the emissions from traditional kilns, measuring CH4, CO2, N2O, CO, NO, NOx, PM, PAH and VOC emissions. The global warming potential (GWP) is measured in CO2-equivaltents and various pollutants have a much higher GWP than CO2 itself. Pennise et al. states that products of incomplete combustion (PIC) are most harmful in terms of GWP. Depending on the kiln, the emissions can contain up to 13% of PICs. In the EEP funded pilot project “Vuthisa Biochar Initiative”, emission research was done by the independent South African company “Airshed”. It measured the emissions from the kiln produced by Vuthisa, comparing it to the findings presented by Pennise et al., 2001. The following conclusion was drawn:
“Vuthisa Technologies uses after-burning to reduce emissions. The US EPA states that afterburning is estimated to reduce PM, CO and VOC emissions by at least 80%. PM, CO, CH4, VO and PAH emissions reported include an 80% reduction. The CO2 emission rate includes additional CO2 as a result of the conversion of CO and CH4 (23xGWP). The additional CO2 as a result of the conversion of other organic compounds are assumed to be immaterial.”
Organic waste ferments and primarily emits methane into the open atmosphere. Processing it into charcoal prevents this. Emission composition strongly depends on the material as well as the circumstances like temperature, humidity and availability of oxygen. Vuthisa was assisted by world renowned biochar expert Dr Hugh McLaughlin in determining the kiln size, number of internal retorts to be used, length of flue stack and general operating procedures to achieve good quality biochar. Further to his input John Hofmeyr introduced the trilobe concept (pictured above) to pyrolise small diameter feedstock such as sawdust.
Ultimately the South African Government wants to alleviate poverty by assisting entrepreneurs to employ and train a skilled workforce that can eventually branch out to produce the biochar/charcoal as part of Community Based Organisations and Vuthisa would secure the market. Vuthisa Technologies was registered with the Fibre Processing & Manufacturing SETA and Ngaphakathi Professionals have so far trained 40 course attendees in the art of manufacturing charcoal and Biochar using Vuthisa kilns and received certificates. The kiln has much potential as a potential learning tool.
The market potential for waste management solutions is large. Besides straightforward timber logging and saw mill companies, also agro-residues like cotton stalks, rice husks, peanut shells, sawdust, coffee, tea and floriculture residues as well as invasive aquatic weeds are suitable to turn into charcoal or charcoal dust that can be pressed into charcoal briquettes. In South Africa reside 9,000 maize farmers, 4,000 wine estates and 1,500 sugarcane producers which are only the large scale farms. Further to that there are thousands of tea estates, saw mills, timber companies and various grain and oilseed farms in South Africa. The disposal of this agricultural waste goes at a cost because it has to be transported and also a disposal fee has to be paid. Converting the biomass into charcoal or biochar on the spot is a very attractive option. Due to shortened cycle times (4 to 12 hours) small diameter feedstock (commonly found in landfills) that typically turns to ash in larger kilns and prolonged burns can now successfully be carbonised.
This project has very good replication possibilities. Despite much progress, many Southern African countries, including South Africa, experienced the global economic crisis with a recession looming (Statistics SA, 2014). It has affected economic growth over the last four years, prompting a deceleration in rate of economic growth in South Africa. In our view value adding or processing waste streams into products of high value can lessen that impact. The demand for Biochar and charcoal produced efficiently is certainly growing. We envisage that the following industries (around the world) could benefit from having a simple biochar kiln on site to either utilise the biochar or to sell it: Small subsistence farmers, Commercial farmers, Poultry farmers, Working for Water Implementing Agents, Landfill sites, Sawmills, Tobacco companies and Water Treatment plants to name a few. The latter has special significance. The South African government also has a favourable tax arrangement in place for companies that hire workers to process methane emitting waste.
- The biochar produced in the Vuthisa Biochar Retort have also been tested by Protechnik in South Africa in 2016.The report: (https://vuthisa.files.wordpress.com/2016/06/lwp280_390protechniktestresultsf4662-issue-5.pdf) includes two examples of biochar made inside the Vuthisa kiln namely VTK1 and VTP1. Sample CCC1 is Calgon Carbsorb 40 from Messrs Chemviron Carbon and is a coal-based activated carbon which is used as a standard for comparison of the surface areas. The comparative surface areas are as follows: VTK1 – 71% and VTP1 – 63%, derived from the BET/CO2 values. Active surface area measured by the BET/CO2 procedure is an indicator of biochar’s adsorption capacity. This demonstrates that the adsorption capacity of biochar is not that far off from activated carbon and can come in at a fraction of the cost.
- A pilot project was performed by John Todd Ecological Design in April 2015 whereby grey water filtering tree pits were constructed in Langrug, an informal settlement located in South Africa’s Western Cape region to receive water from two of the more successful ad-hoc sewers constructed and maintained by the community. Vuthisa Technologies supplied the Biochar, which is used as a filtration agent. This informal sewer system can in future be improved upon by creating a disposal point which makes best use of the contaminated and nutrient rich greywater. By using this waste-stream to grow a tree, many problems were solved at once: eliminating danger of contact with greywater, generating soil and shade, ‘greening’ the community, and accomplishing separation of greywater and storm water. Over time, soils generated in these tree pits will help to absorb storm water, mitigate erosion and prevent pollution entering the Berg River. A combination of 20 kg Biochar mixed water and activated with worm tea being poured into the tree pit Greywater is then routed to this tree. Apart from greywater filtration a huge variety of synthetic organic contaminants (SOCs) such as pesticides, pharmaceutical residues, fuel compounds, and industrial wastes heavily impact the safety of surface waters collected for drinking in communities around the globe (Blacksmith Institute Report, 2014). Decentralised water treatment plants using biochar to filter the water is a very viable solution. A PDF version of the outcome of this project can be made available on request.
- Vuthisa kilns were shortlisted and used in a baseline research study called “Assessment of the potential to produce biochar and its application to South African soils as a mitigation measure” funded by DFID. It can be accessed here: https://www.environment.gov.za/sites/default/files/reports/biocharreport2015.pdf A financial model created by the authors showed that Vuthisa kilns can operate on an IRR of 15% if a wholesale price of 440 EUR/ton can be achieved. The average global wholesale price achieved for Biochar is 1500 EUR/ton. Component depreciation and CAPEX is included in the above calculation.