Steam Weeding

Basics

• Conventional Industrial Agriculture relies heavily on Pesticides that, while effective at controlling weeds, have a variety of drawbacks.
  • Short Term (Killing Beneficial Insects / A Similar Concept to Bycatch for things like Rodenticides etc) and Long Term ( Bio-Accumulation with past ones such as DDT etc)
  • Long Term Human Health Risks for Workers
    • The exposure for those consuming food produced in an area using pesticides/herbicides is minimal, and even then simple Fruit Washing / Vegetable Washing fixes that as well etc
    • HOWEVER if you are walking in a field with a Pesticide Sprayer or Fogger , and ESPECIALLY if you don't wear PPE your Accumulated Exposure will be insanely high, hence the Leukemia/Lymphoma rates, and recent lawsuits in the USA about WD-40 / Roundup (Herbicide) etc
  • High Cost
    • Even if the latter are handled with Pollution Control Measures for Agricultural Runoff / Soil Contamination / Measures for limiting Honeybee Deaths Attributable to Pesticide Use
    • Furthermore, from an Appropriate Materials standpoint, short of Nicotine Solution Pesticides / other Bio-Pesticides , most are incredibly complex to make and/or require intermediates like Phosphoric Acid or even Phosgene (that's right, the thing used as a chemical weapon ) so is probably a no-go
• Thus an alternate method is needed for Organic Agriculture , as well as Integrated Pest Management
• Traditionally, organic agriculture has relied on Tillage or Cover Cropping for weed control.
• While these methods avoid the use herbicides, they have their downsides.
  • Tillage can damage soil life and structure, resulting in a loss of valuable nutrients and Soil Organic Matter.
  • Cover crops may compete with cash crops for nutrients and water, although this depends; Bait Plants and Co-Cropping can be beneficial (Re: Kionhekwa )
• Flame Weeding have been used with success, but often rely on propane gas from fossil sources.
  • Also Flame Weeding cannot be used in areas with a high Wildfire Risk and the Rows cannot have Companion Planting etc, but rather Mulch or worse yet Bare Topsoil
• Steam Weeding has none of these limitations, and short of potentially messing up Soil Bacteria in treated zones is easy to accomplish, can be either highly selective with a Steam Wand and small nozzle, or even be scaled up to a Boom Arm sized unit. Pesticide Resistance is also not an issue
• Short of Water Availability (and to a lesser extent Fuel Availability / Electricity Cost it is also a cheap method

OTS Options

Low End

Dynasteam

• Supposedly Reaches 65 PSI (~4.5 Bar) , 300 Degrees Fahrenheit ~149 Degrees Celcius
• ~86 USD (Although currently "on sale" on amazon original price of 95 USD, ALTHOUGH this may just be New Old Stock as well )
• Supposedly VERY weak in that it has to re-pressurize after not more than a few "doses" which are anywhere from 5-10 seconds each
• The Spike Attachment is also supposedly quite flimsy
• All in all quite limited, but shows the concept is at least moderately sound
• Downsides are essentially Heating Power and/or Water Tank and/or Pressure Tank
• All of which may be solved by a Flash Boiler
• The (Mostly Dead) Website for the Product
• A YouTube Advertisement for the Product ( ~2 Minute Watch ) by It's YouTube Channel
• A Short by the YouTube Channel "GardeningProductReviews" Titled "DynaSteam DS1600 Steam Weeder in Action" (Shows them using that model on a brick surface, no before/after so it could have done nothing for all we know)
• The 86 USD US Amazon Listing

Utilizing OTS Steam Cleaners / Steam Mops etc

• From Personal Confirmation (Albeit with a Cooking Thermometer and no-tool on the end) a "Bissell PowerFresh" produced a constant 100 Degree Celcius Wet Steam
• So in theory it should work
• Should run out and try it sometime
• Lack of High Flow and/or Boiling Water Drops to Kill Roots may prove problematic
• Also Corded
• A Video by the YouTube Channel "Melissa - Empress of Dirt" Titled "How to Remove Weeds with a Steam Cleaner" ( ~3 Minute Watch )
  • They showed about 4 days from treatment until full brown death
  • Used a Steam Cleaner rather than a steam mop, but same concept
  • I was looking into these a while back when i was probably looking this up to beging with, not for showing another person, BUT Automotive Detailing channels use these quite frequently and had good recommendations, granted will they work for this application is another matter

OSE Design

• Essentially a Pyrolysis / Gasification - powered steam weeder, which puts out superheated steam to kill weeds.
• This device can use all kinds of dry biomass for fuel. Pelletized biomass such as wood pellets should work well.
• The saturated steam from boiling water runs through a copper coil which is externally heated in the pyrolysis unit, creating the superheated steam. (Re: Flash Boiler
• Charcoal / Biochar is generated as a byproduct with Non-Char Burning Gasifier Designs, making the process carbon-negative.
  • Pyrolysis Oil could be collected in theory, but short of if done in a Sawdust Gas Filter / Charcoal Gas Filter / Activated Carbon Adsorber this would add a rather significant amount of Design Complexity
• A Pressurized Water Boiler could also be used, although this introduces the risk of a Boiler Explosion and the required risk management ( Boilermaker level Weld Quality Control etc) where pressure is not the main goal (Such as a boiler for a Steam Engine ), but rather Temperature and Volume

Components

• A Biomass Gasifier / Pyrolysis Kiln to work as the heat generation core
  • Looking into using a CHP Powercube would be especially interesting for Lifetrac mounted steamweeders
• A Flash Steam Generator
  • (Most Likely Copper ) Coiled Piping / other Heat Exchanger design pending further analysis (most likely of a Water Tube Boiler Configuration
• A small Electric Blower Fan for Forced Air to the TLUD (either could be required, or just be for startup / heat output boosting)
• An Arduino that controls:
  • The fan
  • The Boiler Feedwater System
  • The Steam Regulator
  • IO and Safety Systems (Although Redundant Controls akin to Safety Instrumented Systems may be a good idea)

Media

A Photo of a Large TLUD Gasifier that seems highly adaptable to use as a Flash Steam Generator, built by Rob Diermair, Biochar Ontario.

Uses

• (Organic) Weeding
• Invasive Species Control
• As a Steam Generator for applications in need of High Volume High Temperature Steam / Working Fluids Such As:
  • Torrefaction / Pyrolysis / Gasification / Thermal Oxidation etc
  • Gas Stripping (Mainly an Open Source Chemical Stripping Column for Bio-Refinery Operations )
  • Soil Sterilization / Biomass Sterilization etc, albeit not to the pressure of an Autoclave

Internal Links

• Open Source Flash Steam Weeder
• Flame Weeding

External Links

• The Wikipedia Page on Thermal Weeding
• Soil Steaming Blog
• paper: A direct-fired steam weeder
• "food drying with superheated steam"
• Wikipedia: Soil Steam Sterilization
• Flame vs. Steam
• Green Steam