tags:: cyber valley

- during 9 month of living in [[cyber valley]] i identified two key problems
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- lack of comfort due to enormous humidity
- fertility limitation for a certain class of plants
- surprisingly both problems can be solved with a low cost stove design targeted for sustainable heat extraction, [[phytomining]] and [[biochar]] production as a free byproducts
- this article outlines rationale and design requirements for successful construction of so much needed device
- background on heat source
- humidity in the region according to our sensor network during wet season fluctuates between 80% and 90%
- mold goes everywhere: clothes, electronics rot, health issues arise
- i convinced my self that without affordable and sustainable source of heat it is impossible to live comfortably in this environment
- lets consider 5 available options for heating
- | heat source | cost | efficiency | polution | availability | sustainability |
|----------------------------|---------------|---------------|-------------------------------------------------------------------------------|---------------------------------------|--------------------------------------------------|
| grid electricity | high | high | coal-fired: high | available, but unreliable | no |
| autonomous electricity | high | high | solar or wind: low | require major investments | moderate |
| biowood | low | moderate | low if [[biochar]] is byproduct | ubiquitous | highly sustainable |
| delivered gas | moderate | high | moderate | available, but hard for remote locations | no |
| biogas | low | moderate | low | requires skills and minor investments | highly sustainable |
- from the comparison table its seen that although does exist easy solutions such as grid electricity or natural gas they both are not sustainable and quite expensive for operations
- although i do have solar station and is going to install wind array, i personally do not think it is affordable source of heat, especially given regional poverty of locals
- so only two options left: biogas and wood which both are affordable and can be highly sustainable for the region
- my understanding is that biogas is outstanding source of heat but it requires skills to operate and is less scalable
- so the focus of this article is to outline the design of sustainable, cost efficient and pollution minimized stove
- background on soil fertility
- in general volcanic soil, [andosol](https://en.wikipedia.org/wiki/Andosol) which is present in the region is quite fertile
- a lot of local plants have been adopted: [[coffee]], [[avocado]], [[banana]] are growing well without ado
- the problem stems from the fact due to heavy rains and soil structure elements are washed away shorlty from the upper layers of soil
- we prepared a good compost layer for one bed and its gone in 3 days of rain nearly completely
- the result is that whole class of food which is vital for our diet (e.g. tomatoes) do not grow well without chemicals and heavy maintenance
- the solution to the problem is ancient soil regeneration practice: add biochar to the soil
- biochar is probably the most sustainable low cost heat source if done properly
- must be responsibly sourced
- pyrolysis must be done at lower end of spectrum: ~400c for maximizing output
- burn chamber for sustaining pyrolysis must operate at ~900c to minimize NOx
- burn gases must be recycled for a more complete and clean burn
- resulting process provide 4 substantial benefits:
- [[biochar]] is fundamental resource for [[soil]] fertility that lasts thousand of years
- cheap and sustainable [[heat]] source
- up to 30% of [[carbon sequestration]] from input biomass as the only practical solution for [[carbon balanced society]]
- [[phytomining]] opportunity as burn chamber require maximum burn of matter
- necessity for a new stove design
- now i hope that i convinced reader how impactful can be such a simple process
- the problem with idea is that a stove that combine all necessary requirements do not exist
- in a warm climate countries stove culture is not existant, hence the market of stoves
- in a cold climate countries stove culture is more focused on a complete burn, rather on balanced biochar and heat production
- high tech biochar solutions which are focused on biochar production are too big for a household or small community
- low tech biochar solutions from blogs and youtube are not practically designed for operating at home
- i was struggle to find ready to use design during last several months, so i decide to design a stove for my needs
- there is no issues with materials as indonesian market offers good high temperature bricks and steel
- so everything can be done quite fast and cheap
- requirements for a design
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- 2 chambers
- the most important aspect as pyrolysis and burning chambers must operate at very different temperatures
- pyrolysis process is efficient at ~400c
- burn must be done at ~900 in order to have the most possible clean output
- afterburn of pyrolysis output
- pyrolysis process extracts oils and syngas from wood: up to 70% from biomass
- its theoretically possible to sustain the pyrolysis proces using just the output of the process
- i don't think its a strong design requirement to reach such level of efficiency
- when oil burns NOx, SOx and CO is released which is not good
- so the strong design requirement is to burn output of pyrolysis at ~900c
- i deliberately letting go post processing of syngas and bio oil
- adding such a requirement will turn the stove into an oil refinery station which is not a goal
- the goal is to achieve a reasonable balance between affordability, simplicity and pollution
- and afterwards carefully measure the pollution
- vortex secondary burn
- improve efficiency, reduce pollution, visually appealing
- 
- although is not critical requirement of the design
- but it looks like quite a simple feature to add wow effect to the final product which is important
- [example and video](https://www.youtube.com/watch?v=_K0eQa-QEBU) and [more](https://www.youtube.com/watch?v=ZSRSKkHcgB8)
- also it works as efficient afterburn process
- water heater exchanger
- key heat utilization of the design must be in ability to heat water
- stable source of hot water is important for comfortable living
- the most efficient way to distribute heat evenly throughout the house is water circuit in the floors
- hence the design must be optimized for efficient water heating
- excessive hot water can be utilized for outdoor hot tube which is really cool
- air heater exchange
- most wood sources which are ubiquitously available in our case are wet
- clean and efficient combustion requires dry wood
- it is a good idea to utilize some part of heat for drying the wood
- organizing heating cabinet requires ability to have hot air
- simple and dumb design
- important for dyi accessibility
- simple design are usually cheap to produce
- its crucial for ability to scale production
- usually serves well for reliability
- simplicity of operation
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- both chambers must be easily maintainable
- ability to load and unload wood is essential for comfort of operation
- materials
- materials being used must be available on local market
- and must be reliable for convenient lifetime operations
- available high temperature materials are
- [sk34 bricks](https://www.tokopedia.com/bentengapisby/batu-bata-tahan-api-fire-brick-sk-34-straight-sk34?extParam=whid%3D7334506): sustain up to 1400c
- [stainless steel 310](https://ptgaja.com/stainless-steel-310s/): sustain up to 1093c
- lets compare them
| property | 310 stainless steel | sk34 bricks |
|-------------------------|---------------------------------------------------------------------|---------------------------------------------------------|
| maximum temperature | up to 1150°c | up to 1400°c |
| thermal conductivity | high (14 - 25 w/mk depending on temperature) | low (~1.0 w/mk), providing excellent insulation |
| thermal expansion | 17.3 x 10^-6 /°c at 100°c (expands with heat) | very low (0.5 x 10^-6 /°c), minimal expansion |
| strength | high mechanical strength | lower mechanical strength, high compressive strength |
| corrosion resistance | excellent resistance to oxidation and corrosion | good in neutral environments, less so in acidic conditions |
| fabrication flexibility | easily fabricated and welded into complex shapes | requires careful assembly, not flexible, cut to size |
| cost | generally more expensive | generally less expensive |
| durability | durable under mechanical stress, can deform under heat | brittle but stable at high temperatures |
| weight | heavier, impacting installation and support structures | heavy, requiring robust support structures |
| maintenance | low maintenance, can be welded for repairs | individual bricks can be replaced if damaged |
| insulating properties | poor insulator, additional insulation may be required | excellent insulator, retains heat within the chamber |
- steel 310 is reasonable to use due to durability, repairability and corrosion resistance
- steel 310 require plasma cutting and tungsten welding with argon which complicates dyi applicability
- anyway steel 310 cant be used alone due to low insulation properties
- so creating a stove purely from sk34 brick looks cheaper, more flexible and elegant for a poc implementation
- shutters can be implemented using ready-made cast iron plates or [heatproof glass](https://www.tokopedia.com/sumberpackingjakarta/kaca-tempred-kotak-tahan-panas-5mm-x-277-x-387mm?extParam=ivf%3Dfalse%26src%3Dsearch&refined=true)
- operational regime
- it must as be as compact as possible in order to sustain one family with every day heat demand
- in order to operate on a daily basis at the evening when heat and sauna is really required
- so the cooled batch of biochar can be processed in the morning to repeat the cycle next evening
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