Low Voltage Controls: Part 1


Last weekend I had the privilege of leading Living Web’s first workshop for 2018.  Tech workshops tend to work best in the winter, before the growing season kicks in. Cold weather and a stiff wind kept us in the classroom and bundled up tight for a brief tour of some of the low voltage control systems around the Grandview Biochar Facility.

Leading a six hour workshop means you can take your time and cover the fundamentals before honing in on the specifics.  Still, understanding how to use low voltage controls to help run your small farm more efficiently is no small task.  I thought the blog format would be useful as a way to cover some of the highlights from last Saturday while providing links for further study.  I’ll start out today on a brief soapbox before coming down to introduce some basic control circuit vocabulary.  Next month I’ll pick it back up and finish by mapping out some control circuits that include some readymade controllers to do some simple, but necessary work.

Appropriate, and Inappropriate Technology

Last weekend’s controls workshop was about introducing the vocabulary of some of the behind the scenes processes that keep us comfortable, safe and efficient.  First off, we’re not in a position to advise building these systems from scratch.  It’s important to know your limits, and recognize when you put you people and property at risk.  That said, I’m a firm believer that, as owners of these appliances and machines that play such an integral role in our lives, it’s at least in some part our responsibility to understand, and have the ability to troubleshoot and perform basic repairs when the need arises.

When we talk about controls, it’s important to recognize the difference between those that remove the human element – rendering us lazy and unaware – and those that we can work alongside, gathering useful data and substituting human effort for only the most mundane and inefficient tasks.  Take for example the case of irrigation controllers: today’s newer models have ‘improved’ upon older ones by including wi-fi connectivity to access weather forecasts and control irrigation solenoids accordingly.  Contrast this to the RainBird SMRT-Y soil moisture sensor kit that saves water by interrupting an irrigation schedule when the soil is already moist, and works alongside any 24 volt irrigation timer, whether the internet is down or not.  Ask yourself, do you really need to control your sprinkler with a cell phone?  We’re all familiar with the narrative of our tendency to overplay high tech systems that can leave us exposed when these systems fail.  Of course I understood the useful applications of these systems, but there’s a time and a place:  when user-repairable components are replaced with non-repairable parts in the name of technical progress, something is lost.

The Farmbot Genesis Open-Source CNC Raised Bed. Clocking in at $2495 this machine is essentially a watering system that allows you to plant your garden as a videogame, pushes weeds underground (no mulch?) and sends text message alerts when your crops are ready for harvest.

I’m only part Luddite: no doubt, the Farmbot is an amazing work of open source tech that will serve well as an educational tool, and to some become a gateway to sensible agriculture.  And there are inherent advantages with IOT when applied to small agriculture, as long as we maintain a means for human intervention.  The SwitchBox control is a complete kit for controlling standard 120V outlets with your cell phone.  And, for those more initiated, there are many online tutorials for DIY versions of SMS controlled outlets at a much lower cost.  I’m sure there are many of us that would like one of these to open the chicken coop door, or start the block heater on the tractor on a frosty morning.  Earlier this summer in our greenhouses, we used a combination of two Android apps that make use of older, otherwise irrelevant phones: Tasker for automatically controlling a phone camera for overnight data collection in some germination trials, and Alfred which allows you to use your phone as a remotely monitored security camera.  With a motion activated alert feature, certainly someone could use this to catch a chicken thief in the act.

Low Voltage Controls

High tech aside, let’s get back to basics. A simple electrical control system really only involves three things: a power source, a switch and a load.  A common light switch will allow power from the utility to energize a lightbulb.  Low voltage controls, however, are inherently safer, more cost efficient, in some ways more capable and easier to install. First, we’ll take a look at some basic components of a low voltage control system: transformers, switches and relays, and see a few simple control circuits we built for the greenhouse and our tracking solar array.

A small doorbell transformer like this takes 120Vac down to 24Vac and typically provides enough power for relays, thermostats and more in our control circuits.

Transformers are devices that either raise or lower an incoming primary AC voltage to a usable secondary voltage.  Depending on the application, transformers can ‘step up’ the incoming voltage (microwaves, arc welders) or ‘step-down’ transformers such as those on the telephone pole in your neighborhood.  We’re most interested in the 24V control transformer.  You can find these everywhere, chances are you’ve already got at least one for your doorbell or inside your furnace.  For most applications around the Grandview Facility we’re using pri:120V, sec:24V transformers rated at least for 40VA. VA is very similar to Watts: a measure of the amount of power a transformer will provide.

Switches come in an immense variety of styles and functions.  Since there’s no way I could even come close to covering it all, I’ll mention a few interesting ones we’re using in our control circuits.  But first, we need to understand a few basic terms.

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Admittedly this is a little dry, so let me try to inspire showing a popular example of a way we can use switches to make our lives easier: the three-way lighting switch.  Chances are you have this circuit in your home, where you can toggle an overhead light on or off from either of two switches located on opposite ends of the room.  If you were to pull off the switch cover plate and observe it’s likely any novice would be overwhelmed by a indiscernible mess of wires.  However, when expressed on a line diagram it’s easy to see that a three-way lighting circuit is nothing more than two SPDT switches wired in series.

The light is energized when both SPDT switches are in the up or down position. Move either switch and the circuit is broken.

So far we’ve only covered small, manually operated switches.  A crucial step towards understanding low voltage control systems involves knowing how relays work. Think of Relays as electrically powered switches, that are often employed by control circuits to energize larger loads, or otherwise isolate circuits.  Just like switches, relays can look quite a bit different from one another – each with its own application.  The starter motor solenoid in your car is a type of relay.  Turn the key, and control power from your car’s ignition switch energizes a coil, that closes a circuit from your battery to the starter motor.  If your car didn’t have this relay, your ignition switch would have to be rated for the full load current of the starter motor: as much as 250Amps or more!  What we’re going to focus on are 24V electromagnetic ‘ice cube’ relays that close a switch between common and ‘normally open’ when 24 volts is applied to ‘the coil’.  Scroll through the photos below to learn a bit more about relays.

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When you begin to imagine the applications for relays, first you’ll realize that relays are everywhere, and then you may see that relays can make a lot things possible that you might not have otherwise thought of.  For example, our greenhouses are the constant inflation type: requiring a small blower to maintain air between two layers of plastic film. They’re great for insulating air pocket it creates and can keep a tight greenhouse much warmer in the winter than single layer poly versions.   However when the grid goes down, we’d otherwise lose inflation and our greenhouse walls would be a floppy mess if we didn’t have a relay activated, battery powered DC backup blower.  This circuit is simple:  A 120Vac relay stays energized as long as the grid is present.  The DC blower is connected to the battery by way of the N/C contact the relay.  So, as long as the grid is present, the relay is energized and makes common to N/O, and the DC fan won’t turn on.  It’s not until we lose power that the relay reverts back and makes common to N/C, completing the DC blower circuit.

DC backup with a 120Vac ‘grid sensing’ relay

Next time I’ll cover some of the ‘ready made’ controllers we use, along with relays and switches, to do fun things around here, like energizing a stoplight and buzzer when our biochar retorts get too hot, or, for optimizing our solar kiln operation.  I’ll wrap up today with one more example of how we use relays: the motor reversing circuit on our our 400W tracking solar trailer.  In this case, we’re using an Arduino microcontroller to advance our simple tracker westward 15 degrees every hour.  The arduino board sends out a 5v signal to a relay that’s only rated for switching 5 amps max.  We had to then step up to another relay capable of handling the full load of the tracker motor.   At the end of the day, the tracker motor reverses by switching polarity and reverting back to it’s original, pointing eastward, morning position.  We programmed the arduino board to do this automatically, but we’re not pros, so we used relays to make sure that the motor couldn’t receive a command to move forward and reverse at the same time.  If the arduino fails to recognize the end of day, repurposed N/C lawnmower safety switches are wired in series and used as limit switches, so the tracker won’t tear itself apart.  See the circuit diagram below and you’ll see how a couple of relays both protect the motor and switch motor polarity upon receiving the signal.  More drawings are available on our Archived Workshop Handouts page.


Biomass for the Masses

by Richard Freudenberger, Living Web Farms Resource and Alternative Energy Coordinator

Call it firewood, biomass or solid fuel, it’s still one of the most reliable ways to heat your home—but only if you do it right. Even long-time wood-burners can disagree on what is “right,” so we’re going to do our best to clear the air about best practices in wood burning and selecting appropriate wood-burning stoves.

Getting the most out of firewood is nothing new. Ben Franklin’s heat-radiating stove, Count Rumford’s clean-burning fireplace, and Scandinavia’s wood- frugal tile masonry stoves were all an 18th -Century response to inefficient burning or regional shortages of wood fuel. Enclosed metal and cast-iron stoves followed in the years after, and wood cook stove innovations came close behind, all direct developments of efforts to control temperatures and fuel consumption.

Most of that development went away with the advent of natural gas and electricity, but petroleum shortages and the back-to-the-land movement of the 1970s sparked a renaissance in wood burning which has largely continued to this day.

The Good and Bad of Wood

Wood is a renewable resource that is carbon-neutral when used properly in a certified stove or fireplace insert. Contemporary stoves, with efficiencies of 80 percent or more, make better use of their fuel than most fossil-fuel furnaces and electric resistance heat in any form.

And because wood is a local commodity, there’s no worry about infrastructure, grid stability, scarcity or any of the other risks that come with processed fuels. If you’re fortunate enough to have even small acreage, you can glean your supply on site, from deadfall or proactive management. If not, you can always order a load, split or uncut, and store it pretty much indefinitely if you have it under cover.

But there is a downside. Smoke from residential woodstoves contains an especially damaging pollution called fine particulate matter or PM2.5.– airborne respirable particulates with a diameter of less than 2.5 microns. These super-fine particles in smoke comprise about 93 percent of the smoke’s particulates and can get deep into the lungs, damaging the pulmonary system, blood vessels, and heart.

Other pollutants in smoke include carbon monoxide, volatile organic compounds (VOCs), and benzene. Unregulated residential wood smoke can increase particle pollution to levels that pose serious health concerns, and in some rural areas constitutes a significant portion of the fine particle pollution. More about the health effects of PM2.5 here.

A Brief History of Wood Burning

How we got here from there is an ongoing saga that started with the shift to airtight wood stoves that came with the OPEC fuel crises of the mid-1970’s. Woodstoves now easily account for 75 percent of the cordwood burned in residences, the remainder being fireplaces which are used much less frequently. There are over 11 million homes in the United States that use wood for either primary or secondary heating.

Because the only controls in early airtight stoves were an air inlet and a flue damper, users quickly learned that in order to conserve wood they could throttle down the air inlet and slow the burn once the fire was fully engaged. The result was a smoldering and very dirty fire that would release 40 to 60 grams of particulate matter into the air every hour.

By the 1980’s state agencies and the federal EPA began testing airborne particulates, and in some jurisdictions set wood burning bans on especially bad days. This prompted manufacturers to research and develop clean-air models, which is when the first catalytic and “high-tech” stoves (called non-catalytics) came onto the market.

In 1988 the EPA initiated what would become a three-phase regulation program that required woodstove manufacturers meet a certified emissions standard of 8.5 grams/hr. (5.5 for catalytic models), followed by a 7.5/4.1 gram/hr. standard a few years later. In 2015 that dropped to 4.5 grams/hr. for all certified woodstoves and included previously unregulated outdoor wood boilers, wood furnaces, and pellet stoves. A Phase IV performance standard for 2020 sets the limit at 2.5 grams/hr. for all cordwood burners. Follow this link for information about wood heaters that are in compliance with the 2015 New Source Performance Standard (NSPS) for New Residential Wood Heaters.

So now we’re at an emissions level that’s less than 8 percent of what it was thirty years ago. But just as important we’ve seen efficiencies rise dramatically, so far less fuel is being burned in today’s certified stoves to provide the same amount of heat available from those high-emissions stoves of decades past.

How Wood Burns

The magic happened when designers began looking at the stages of combustion inside the stove. Wood itself doesn’t actually burn. The initial heat source–a match, a coal, burning tinder—decomposes cellulose in the wood starting at about 300 degrees F by breaking chemical bonds between compounds, a thermal decomposition process called pyrolysis. Offgassing of water vapor and volatiles (smoke comprised of oxygen, hydrogen, and carbon) occur at that point, and as temperatures rise to around 540 degrees F, most of the water vapor is driven off, and a large quantity of volatiles are released in a process of primary combustion, which generally occurs below 900 degrees F.

These volatiles, known as secondary gases, contain combustibles such as methane and methanol, along with carbon dioxides and oxides of nitrogen. In order for the secondary gases to burn, temperatures must reach the 1100 degree F range with sufficient oxygen present. These conditions don’t exist in close proximity to the wood because primary combustion is taking up the necessary oxygen.

Secondary combustion is critical to a clean burn and high efficiency and depends on just the right supply of air at high enough temperatures. Too little air cannot support combustion and too much cools temperatures below the needed threshold because its nitrogen absorbs heat.

Left behind is ash and carbon char, which combusts slowly because of the lack of oxygen. With the gases gone from the wood, the carbon chains of cellulose and lignin molecules remain behind as charcoal, which burns for an extended period with a low heat output. This third phase of combustion is still significant because in addition to releasing additional energy which adds to fuel efficiency, the charcoal extends the burn through the night so the fire can easily be reignited with fresh fuel in the morning.

The combustion of wood occurs in varying zones at different temperatures

Two Good Alternatives to a Dirty Burn

Legacy woodstoves, the airtight stoves sold before July 1988, are still in use, either because they are original installations still going strong, or they’ve been sold on the used market as economical buys. As a matter of fact, they are a very poor investment due to their high rate of wood consumption, not to mention a burden on local air quality.

Current certified woodstoves have evolved to include design features that encourage all-important secondary combustion so critical to a complete burn. Popular technologies include the use of catalytic combustors, extended circulation of gases in the stove, controlled secondary air manifolds, baffles, and thermal-mass stove construction to hold heat. More recent entries are smart stoves that use sensors and computer controls to adjust airflow or recycle heated exhaust air.

For most people, clean stoves will fall into two categories—catalytic and non-catalytic. The catalytic types direct exhaust smoke through a ceramic honeycomb catalyst that, when heated to a temperature of around 550 degrees F, burns off volatile gases and strips out particulate matter. Catalytics tend to have a slightly higher efficiency and longer burn times than non-cats, but they can also be a bit more expensive and require more user input. They will not tolerate wet wood, colored or waxed kindling paper, or trash burns of construction waste with nails or wire, as these will inactivate the catalyst unit over time. Even under ideal conditions, the life of a catalyst is limited to ten years or so before it must be replaced.

Catalytic woodstoves rely on a coated ceramic honeycomb operating at high temperatures to keep emissions within limits

Non-catalytic stoves depend on internal airflow and delivery to keep secondary burn temperatures in the working range. Internal baffles keep gases in the combustion zone longer to assure a more complete burn and pre-heated air delivery enhances the secondary burn process. The firebox in a non-cat may tend to be smaller because of additional insulation, and its heat output curve may not be as consistent as that of a catalyst type, but the stove requires less user input, and because of the airflow pattern will provide a very visual fire.

Non-catalytic stoves use flow baffles and a carefully engineered secondary burn manifold to meet emissions standards

At the lowest end of the price scale you may still find non-airtight, ungasketed stoves that are not EPA certified. These were banned from retail sale at the end of 2015, and were only exempt from regulations because they are so leaky that they fall under an 11 lbs./hr. fireplace exemption. Generally they are not UL approved, and are not clean burning by any measure. Their only attraction is their price, and they should be avoided. You can access here The List of EPA Certified wood heaters.

The secret to a good burn in any woodstove is to use only dry, seasoned wood, preferably a hardwood species. Moisture has a significant effect on heat value in the fuel, as uncured wood can have 40 percent lower heat value than wood seasoned to a 19 percent moisture content. It takes, on average, about six months of air-drying in most climates to achieve this level of dryness.

Atomizing Waste Oil Burners


Summer HVAC season is coming to a close and lately our local scrap-yard has been teeming with old oil burning furnaces. While Asheville residents are replacing oil burners with updated heat pump systems as fast as they can, conscious builders and tradesmen are recycling the used equipment, and although many of these machines are fully functioning, no doubt many of them still end up at the landfill.  What can be done to keep this robust, sometimes outdated, technology out of the waste stream and put to good use?  The biochar crew at Living Web has been working over the past year to develop oil burning technology for clean combustion of pyrolysis oil – a corrosive, sticky, and heavy liquid coproduct of biochar production.


Conventional Oil Burners

Conventional oil burners are commonly found in older homes and in areas where heating systems were installed prior to the widespread availability of natural gas.  They’re the appliance commonly found in basements, that pulls oil from a large tank, and burns it in a chamber housed directly underneath a furnace or boiler.  These home heating oil (HHO) burners are set up for a specific grade of oil, commonly referred to as #2 fuel oil (Imagine the viscosity of diesel fuel).  In fact, any oil furnace designed for #2 fuel oil can accept up to 20% biodiesel with no modifications.  WNC locals may be familiar with bioheat from Blue Ridge Biofuels – a blend of up to 20% biodiesel and fuel oil.  For those of you outside of the area with oil furnaces and boilers in your home, use this map to find biodiesel distributors in your area.  Also, see the Dept of energy site for suggestions of some simple procedures, such as nozzle resizing, that can cut up to 10% off fuel usage.

These “gun style” burners were pulled out of old furnaces instead of getting crushed at the the junkyard. Conventional oil burners can be modified to accept a wider range of fuels to provide intense heat for many processes.


How do they work?

Conventional oil burners are a tightly packaged system of components: oil pump, blower, nozzle, ignition system, controls and safety mechanisms. These ‘gun-style’ burners work by forcing refined oil through a specialized nozzle at high pressure, creating a mist that ignites in the presence of a high voltage spark.  This extremely fine, or atomized, spray facilitates clean combustion by reducing the particle size of fuel relative to combustion air.  Think about kindling when starting a campfire – given adequate combustion air, small pieces of wood burn quick, clean and hot – It’s the same with an atomized spray.   The right amount of oxygen is introduced, add spark, and the resulting flame is then managed in a burn chamber, where the intense heat is directed across a heat exchanger, warming the air or water in a residential heating system.

Apart from improvements in flame retention and combustion air handling, very little has changed with the gun style burner in decades.  Of course, environmental and resiliency issues arise when considering the extraction and distribution of our remaining cheap petroleum, especially when it’s diverted to home heating use, where there are so many better options.  However, operation of these burners is surprisingly clean, they have to be, or soot clogs the small passageways in a typical furnace heat exchanger.

There are a few more things that make these working with these conventional oil burning technologies so interesting:

  • Liquid fuels inherently have certain advantages: they’re easily stored and metered for predictable power output.  This is essential in certain of kinds of equipment, and merely a convenience in others.
  • Clean combustion requires high temperatures – an advantage when applied correctly.  High temperature heating fuels are not always necessary in a home heating system, but are critical when applied in certain applications, such as backyard foundry or ceramic kiln.
  • Unless otherwise indicated, gun style burners are designed to only burn #2 fuel oil (and up to 20% biodiesel).  Higher concentrations of alternative fuel oils require equipment modifications.  Fortunately, these modifications are well documented: waste motor and vegetable oils are accessible fuel alternatives.

Retrofitting a gun style burner for alternative fuel use requires a few distinct changes to the original design.  Specialized siphon nozzles use compressed air to deliver fuel spray while preventing clogging issues and eliminated the need for the oil pump.  Waste motor oil has a higher flash point than #2 HHO and requires additional fuel preheating. We use a small (surprisingly affordable) PID controlled heating element at the nozzle for reliable startup and consistent operation.  The details go on, and these are not easily understood modifications without a little background and tenacity. Lucky for us, CKburners provides kits and detailed instructions for those starting out.  For our first unit, we bought the block heater and siphon nozzle kit.  For those inclined to sourcing salvaged materials, one could be able to modify an existing oil burner with this kit for as little as $400.

A modified gun-style burner, developed for use with waste motor oils.


Pyrolysis oil

At Living Web Farms, our end goal was a machine not limited to the use of waste motor oils, or even used vegetable oils.  We needed a system that could reliably burn pyrolysis oil – a coproduct of our slow pyrolysis method of biochar production.  In slow pyrolysis, gases are released from dry biomass as it’s heated in the absence of oxygen.  These gasses pass through a condensing unit on their way to a controlled burn chamber.  At the condensing unit, gasses that can be condensed drop out as liquids, where they drain into large holding containers.  Over the course of a few months, heavy oils and tar settle out in the bottom of these containers.  The lightest of these oils are what we call pyrolysis oil, which is separated and stored for use as fuel.  The remaining liquid products, tars and wood vinegar (or, pyroligneous acid) are also separated at this time, where it’s stored and used later for all sorts of interesting things.

Pyrolysis oil has some very different qualities that set it apart from conventional fuel oils.  It requires fine atomization into a hot burn chamber.  It’s highly corrosive, and its viscosity changes dramatically with changes in temperature.  From our experiments, we’ve learned if it’s heated beyond a certain threshold, it won’t return to a liquid form. Since then, we’ve learned this may be due to increased oxygen exposure, and this makes sense too, as if it’s allowed to dry in the sun long enough it can create a hard plastic like shell. These characteristics become distinct challenges when tasked with designing an appropriate burner.   Because of these issues, especially corrosivity and clogging problems, we knew it wouldn’t be reasonable to ‘push’ pyrolysis oil through the tiny passageways in the nozzle of a modified gun style burner.  Our research in DIY metal casting brought us to the babington style burner.

Pyrolysis oil: A valuable coproduct of farm scale biochar production


The Babington style burner

Babington burners were developed in the 1970’s by the inventor, Robert Babington, as a means of achieving very fine atomization spray at low firing rates.  Babington Airtronic burners saw an early market in the 1980s as home heating units in mostly European households.  Today, the technology has been picked up by the US military in remote cooking applications.  Babington burners have a unique ball-shaped nozzle design that not only provides a fuel efficient burn, but also allows for a much wider range of fuels, requiring much less filtration than modified conventional burners.

The heart of the babington burner system is the ball shaped nozzle.  Instead of forcing oil through a nozzle with a pump, now, oil is pumped over the ball, where it forms a thin film as it stretches out over the surface of the ball.  At the equator of the ball, where the film of oil is at it’s thinnest point, it intersects a stream of pressurized air forced through a very small hole.  Atomization is achieved here, where the fine spray of oil passes near an ignition point, more air is introduced, and clean combustion is realized.  Excess oil flows over the ball and back into a vessel (sometimes called a sump) where it is continuously pumped back over the ball.  The original babington burners were designed for high efficiency, low firing outputs.  DIY builders have experimented with ways to adjust heat output (and thus, fuel consumption) by adjusting the size and number of holes in the ball, flow rate of oil, and pressure of air through the nozzle.

Water poured over a ball shaped nozzle as air passes through a very small hole produces a very fine spray

At normal temperatures, our pyrolysis oil is too thick for filtration through standard oil filters.  For us, the real advantage of the babington style nozzle lies in the reduced need for this level of fine filtration.  Since our oil won’t be forced through a conventional nozzle, the fuel only needs to be filtered to the extent that it can be pumped.  Our system uses a 12V gear pump to deliver oil from a salvaged LP tank sump onto a stainless 2” ball with a .03” hole.  Preheat is applied to the entire reservoir through a copper coil heat exchanger, where heat is drawn in from either a very small DIY electric water heater, or off the excess heat generated from the system.  Conventional electrodes and ignition control are sourced from another scrap yard burner.  With this setup, we’ve achieved very clean combustion of pyrolysis oil, at temperatures up to 2000°F in our burn chamber, on very little fuel consumption (½ Gal/hr).

Our burn chamber was built with a modular design in mind.  Either the babington style burner or our modified gun-style burner mount on a flange on the inlet tube.  The burn chamber functions as a crude kiln or foundry with a modest amount of temperature control. The lid removes easily to reveal a universal flange for mounting a water heater, or for accommodating future appliances like a tumble dryer or forced air furnace.  Things get interesting here, where we can maximize efficiency by stacking appliances.  For example, simultaneously we can melt aluminum in the chamber, while heating water, and then sterilizing growing media or drying wood chips, before exhausting through the flue.

Our babington style pyrolysis oil burner: this thing is tank! Built with experimentation in mind, we’ve demonstrated pyrolysis oil can burn clean and hot.

We built our first babington style burner with experimentation in mind.  Honestly, It’s an oversized unit that leaves much to be improved upon.  The preheat system is clunky and requires too long for the system to start from cold.  Our conventional ignition system isn’t reliable with oils it wasn’t designed for.  Overall, there are too many ways this system can fail.  Even with our automated safety controls, this isn’t a machine you would want to walk away from for long, much less leave overnight for greenhouse heating.

For me, it’s not until you pick something apart and start rebuilding that you gain an appreciation for the original.  This winter we’re looking forward to redesigning our babington style burner.  We’ll try to fit it all into a conventional gun style burner package.  Our new system will start reliably (and save energy) by preheating the oil only at the point before flows over the ball, and we’ll include an LP source for cold starts, and possibly lose the conventional ignition source all together.  We’ll be developing more low cost applications for the heat: greenhouse heating, plastics recycling, feed processing and more.

Stay tuned, we’ll be updating our progress on the blog.  As always, send me an email if you’d like to know more.

Conducting a Do-it-Yourself Home Energy Audit

by Richard Freudenberger, Living Web Farms Resource & Alternative Energy Coordinator

There are two benefits to saving energy in the home. One is the financial gain of allocating less of your household budget to keeping the household humming, and the other is the less noticeable advantage of managing consumption for the sake of our planet’s resources. The energy used to generate electricity—whether it comes from coal, petroleum, natural gas, or enriched uranium—requires extraction of a natural resource and all the processing and logistics that come with it. In addition to that, using these resources creates emissions and a waste stream that has to be controlled and dealt with in a responsible way.

The September Equinox is a good marker for those of us north of the equator to make a plan to reduce electrical usage. The weather is turning cooler, demand for heat, light, and cooking is greater, and most of us will be spending more time indoors.

Let’s start the conversation by talking about the typical electric bill. Most of us probably just look at the bottom-line dollar amount and pay the charges, but there’s a lot more information in that bill than you may realize.

A typical residential power bill will show consumption in kilowatt-hours (kWh) and make a comparison with the prior year

The use of electrical energy is measured in kilowatt-hours (kWh), or the amount of power, in 1,000-watt units, consumed in one hour. So, a 100-watt bulb on for ten hours uses 1 kWh of energy. Likewise, a 1,500-watt space heater on for one hour uses 1.5 kWh of energy, or 50 percent more.

In the course of a day, all the lights, appliances, accessory chargers, fans, and so forth in the home draw power in different increments and for varying lengths of time, but at the end of the day, consumption can be measured in a common unit, the kilowatt-hour. Utilities generally work on a 30-day cycle, so it’s a simple matter of dividing the total kWh used in a month by 30 (or whatever number of days the cycle happens to be) to get the average kilowatt-hour usage per day. The bill is then tabulated along with fees and taxes at your utility’s residential rate per kWh, which ranges by state from 9.4 cents to over 28 cents.

It sounds fairly simple, but the problem is that not all appliances use power consistently. Some, like your refrigerator, well pump, or forced-air furnace, may cycle on and off several times an hour, making it difficult to gauge how much power is actually being consumed.

So if you were trying to get a clear picture of how your energy budget was spread out you’d have to be able to measure the consumption of not just the steady draws such as lighting but also the inconsistent uses. Fortunately there is an inexpensive device that allows you to do just that.

The Kill A Watt electricity monitor (manufactured by P3 International) is probably the most well-known, but there are many other choices available online and in home improvement stores at prices ranging from around $13 to $30. Once the purview of professional energy auditors, these devices have dropped to a price point where anyone can take advantage of them.

An electricity usage monitor can be used on any 120 volt outlet and costs less than $30

The monitor plugs into a wall socket and has a built-in outlet that accepts the power cord from the appliance you want to test. Controls on its face allow you to select the mode (it displays watts, amperage, voltage, and frequency in addition to kWh) and can it be set to monitor by the day, week, month or year. Once you’ve entered the cost of electricity from your utility, it will count the cumulative consumption of whatever is plugged into it and convert the data to dollars.

With this information you can make educated decisions about how long to run your air conditioner, whether your refrigerator is devouring more than its share of your energy budget, or if items that use standby power like TVs and printers are worth putting on a power strip that you can shut off after use.

If you are shopping for a new appliance, the yellow Energy Guide label displayed on major appliances is a good measure of how much energy the unit will consume annually in kilowatt-hours. It also provides a yearly estimate of how much it will cost to run based on the average cost of energy. The ratings are categorized by appliance size or capacity, and a further indicator is provided by the Energy Star logo, which indicates high-efficiency models. The Energy Star choices are typically more expensive, but not necessarily by a great deal.

The Energy Guide is a good comparison tool for assessing new purchases and comparing your old appliance’s electricity consumption to a new model

That, in fact, makes them a better buy in the long run, because efficiency is a smarter path to energy savings than simple conservation. Keeping an old refrigerator in service to save the cost of buying a new one simply means that you are spending more each year to operate it, especially if it’s close to ten years old. A new Energy Star purchase will lower operating costs, reduce the need for service costs, and give you the features you want, while paying back the original cost of purchase.

What effective steps you can take to turn an audit of your household power usage into savings? Start with simple things like lighting. Incandescent bulbs are a thing of the past, and compact fluorescents are gradually fading from the scene as well. LED bulbs last ten times longer than icandescents and use 10 percent of the energy while delivering the same amount of lumens, or light output. Replacing every bulb in a moderate-size household will cost as little as $250. You can also take advantage of daylighting for free by opening shades and curtains in the winter which will let in light and some incidental solar energy.

A pre-programmable, or a smart WiFi learning thermostat would also be a good investment, ranging in cost from $100 to around $250, plus installation. These allow you to specifically set your home’s climate control to the times you typically occupy the house, shutting the system down to maintenance levels at other times, resulting in substantial savings. The learning thermostat has a memory that adjusts to changes in your schedule.

Pre-programmable thermostats can be adjusted to suit your schedule and save money by coordinating the climate control system with the hours you spend at home

Water heating accounts for 15 to 17 percent of electricity usage in a typical household, the third largest consumer of household energy behind heating and cooling. For a large family, an investment in an electric heat pump water heater can offer a reasonable payback period, but it’s not really necessary to go to a high-tech fix if you can install a water heater timer (about $55) to control the time cycles that the appliance gets power and a closed-cell foam or fiberglass jacket wrap (about $29) to increase the insulation R-value of the tank. Even setting the internal heater thermostats down to 120 degrees F will result in some savings if the factory presets were set higher.

Phantom load management of the standby electronic devices mentioned earlier are a small but significant part of your household electricity picture. Nationally, standby power accounts for a whopping $11 billion in energy costs, but every little bit of savings helps within the household. The small cubes and black boxes attached to your devices’ power cords are the giveaway that power is being consumed by internal transformers, even when the device is switched off. Plug these into a gang power strip and use the strip’s switch to make sure that no energy is getting to the devices. Problem solved.

The power cube in the wall outlet is about to find a new home on the power strip. Devices like TVs and entertainment equipment usually have built-in standby circuits that consume energy as well

Other than refrigerators, clothes washers are a significant consumer of electricity and water. An electricity monitor will determine if your current washer is power-hungry due to age or just cycle operation, and if you go online to https://www.energystar.gov/products you can research replacement machines that are more efficient. At the Energy Star Tier II level, there are a good selection of products that offer at least a 10 percent energy savings and up to 40 percent water use savings, with costs in the $600-plus range. Horizontal-axis machines are especially efficient and many are domestically manufactured.

Finally, consider having a professional inspect your ductwork and air handling system for leaks and damage. After an HVAC tune-up, a duct inspection can be the most effective path to efficiency, with minimal materials cost. Sub-standard installation and deterioration over time can take a quiet toll through the years, wasting both warm and cool air by not delivering what you’ve paid for to the intended location in the home.




DIY – Make a TLUD Gasifier

By Dan Hettinger, Biochar Facility Manager

Last month I wrote a little about the carbon impact of biochar production, and concluded with the assumption that going ‘carbon-negative’ is likely very possible with simple scale ‘backyard’ biochar technologies.  Bob Wells’ immensely popular presentation on the Tin-Man shows an effective DIY method with a single 55 and 30 gallon steel drum.  Lately, here at Living Web Farms, we’ve been taken by the TLUD (Top-Lit/Up-Draft) Gasifier as an alternate means of DIY biochar production.  In fact, If you’ve followed us closely then you know that we’ve talked a little about TLUD gasifiers before.

I’ll be the first to admit this can be a hard thing for a lot of people to get excited about.  That is, until you look closer at what’s possible with this technology.

What’s a Gasifier?

Chances are you’ve heard about coal gasification as one of the ‘clean coal’ technologies that’s been getting a lot of attention lately.  The merits of this practice are debatable, and not within the scope of our work at all.  Although the principles of the technology are very similar, when we talk about gasifiers, we’re generally talking about much smaller devices that convert biomass into gasses through the application of heat with a controlled amount of oxygen.  Our gasifiers are low tech devices: think of them as vessels filled with biomass and lit with a torch, where just enough oxygen is applied to keep it lit. Pyrolysis ensues, biomass is reduced to carbon, and a myriad of gasses are released. The resulting mixture of Carbon Monoxide, Hydrogen and Carbon Dioxide is (often called Producer Gas, or Syngas) a fuel gas that can then mix with oxygen and burn at higher temperatures than ordinary smoke. Higher temperatures lend to a more complete burn that, when ultimately compared to an open burn, is a cleaner, more efficient process.

In the early part of the 20th century ‘town gas’ was produced as a coproduct of the coking process and distributed throughout nearby communities as a cooking fuel and illuminant.  However, the discovery of cheap fossil fuels made this and the early chemical industry it supported irrelevant. Gasification of biomass saw renewed attention during the world wars where petroleum became so scarce that many European economies were forced to switch up to one million petroleum fueled motor vehicles to operate on syngas.

In 1989 FEMA published a manual on building simple down-draft gasifiers for powering motor vehicles during a petroleum shortages.  Since then, wood gas gurus like Wayne Keith (driveonwood.com) have expanded on these plans to build reliable biomass trucks that are capable of continental travel on a surprisingly low amount of fuel.  Today, there are many outlets for DIY and commercially offered wood gas electrical generators.

The LWF biochar crew built this passive charcoal gasifier to run a lawnmower we found on the side of the road!  Charcoal as a fuel for gasification is a clean choice, as much of the tars have already been driven out, but it burns hot and can lead to different problems.  Look closely and you’ll see how the engine exhaust doubles as the air intake to help make this run a little cooler.

Almost simultaneously in another part of the world, humanitarian engineers were developing small gasifying cookstoves for improved fuel efficiency and cleaner combustion. The World Health Organization has reported that ⅓ to ½ of the world’s population are still cooking their meals on an open fire, and, that annually, up to 4 million people prematurely die every year from indoor pollutants as a result of cooking indoors. There is a huge potential for positive global impact through the development of cleaner biomass combustion technology.

Top-Lit Up-Draft Gasifiers

Born out of years of development was the TLUD gasifying stove.  These devices use chunky biomass (typically wood chips or pellets) as the fuel to produce both a clean flame for cooking or heat, and charcoal, to be used as biochar or sold as a value added commodity.  Along with cooks in the developing world, conscious gardeners and homesteaders have made use of TLUD technology to make biochar from landscape wastes while providing heat for greenhouses, domestic water, canning, or even processing chickens.


Using a TLUD, on chicken processing day at Living Web Farms, the biochar crew maintained 8 gallons of dunking water at optimal temp for easy feather plucking.

The TLUD works on a natural draft of primary air through a column of smoldering biomass.  The process starts when a small fire is started on top of the column.  Primary air is then drawn in through holes underneath – enough to keep it hot, but not enough to create and open burn.  Dense smoke(syngas) is generated, and, once a strong draft is established, secondary air is pulled in through holes towards the top of vessel.  This secondary air mixes with the syngas in the combustion zone where it burns much cleaner than an ordinary campfire.  Limited oxygen just below the flame facilitates preservation of charcoal.  This line between the flame and charcoal is sometimes referred to as the pyrolysis front.

There are many ways to build a gasifier, with varying degrees of sophistication for different applications, and I encourage you to research further on your own.  For the serious DIY small producer, I’d recommend starting with the champion style TLUD.  With it’s preheated secondary air, it’s a little more involved that what I’ve demonstrated below, but worth the effort in achieving a cleaner, neighbor-friendly burn.

The LWF biochar crew built a few champion style TLUDs last fall (see below, end of slideshow for photos).  Of note is the larger of the two, where we expanded on the champion design and offset the flue, so we could use this large flat plate as a heating surface for heating up large pots of water for canning.   What we really wanted a robust stove with longer run times, that would also help move the canning chores (and all that heat and humidity) outside in the summertime. This device will heat 3 gallons of water from the well to boiling in about 45 minutes, it runs at full strength for about 2 hours and yields 2-3 gallons of crushed biochar.

It’s challenging to build a robust gasifier without some welding, though we realize welding can be intimidating (it’s easier than you think) and isn’t accessible to everyone. Below is a slideshow we put together to demonstrate a very simple and robust, large TLUD build from a salvaged 100 gallon propane tank and 2 sections of 6” flue pipe.  You won’t need a welder to build this, but you will need to acquire an angle grinder with a few extra cut off wheels, some good eye and ear protection, gloves, a drill and a couple of self tapping screws.  Locals can try the Asheville Tool Library if you don’t want to buy an angle grinder for just this one project.

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You’ll know that a batch is done when the temperature drops, it smokes a little, and you smell that familiar charcoal scent.  Be prepared,  you’ll need to be nearby to quench the char in time.  If you miss it, your precious biochar will be consumed in the presence of air.  Quenching provides an opportunity to create microscopic fractures in the char that further enhance it’s value as a microbial substrate.  Some biochar gurus will even add mineral amendments, such as SEA-90 or Azomite to the quenching water to help encourage microbes to move in.  pH testing at our facility indicates that biochar made in a TLUD may be more alkaline than biochar made in the retort method.  This is likely due the open-atmosphere nature of the technology that facilitates an increased ash content, especially if you don’t quench it in time.  Use caution when applying TLUD char raw, it’s best to allow pH to neutralize by blending it with rich compost and allowing it to set for a few weeks prior to application in the garden.

Winter is a great time to make biochar at your homestead.  This year, instead of making a burn pile in the yard, save your little stuff that doesn’t go in the wood stove.  “Waste” wood like downed limbs and orchard trimmings that don’t compost easily are perfect feedstock for a manageable one person biochar operation.  With its multitude of applications, ease of construction and availability of materials, these small gasifying and biochar producing devices are deserving of a place alongside the solar cell and bicycle as one of the bedrock appropriate technologies.

Send us an email if you’d like, we’re happy to help to get you started!


Remembering Chuck Marsh

by Patryk Battle and Meredith Leigh

(Patryk:) Chuck was the person I was most looking forward to getting together with at this year’s Permaculture Gathering. I wanted to share with him my delight at having rooted in accidentally broken off branch of Yuzu ( a hardy-ish Japanese citrus that I of course got from Chuck). But the vicissitudes of life and the fact that he left the gathering early meant that we missed each other. Upon learning why Chuck left early, I reached out to him offering Living Web Farms grown Reishi mushroom, produce and of course, any other support we at Living Web might be able to provide but our mutual friend Gred Gross who brought me up to date on Chuck’s situation reported that that a key message from Chuck was “no #$%&! sympathy!”.

Chuck and I had a lot in common. One very unimportant but always personally gratifying thing we shared is a penchant for peppering our speech (when our executive editors found it prudent!) with expletives. Would that I could be as effective or evocative with expletives as Chuck was! He could encapsulate much of what Meredith so eloquently describes below with one or two well-placed expletives.

There are no expletives in Chuck’s response to my offer of support but it is classic Chuck, and I believe more effectively illustrates the depth and breadth of Chuck’s spirit than anything I ever write could. So please allow me to share a lightly edited version of his recent letter to me:

Thanks my bro Patryk,

Sorry to have missed you as well.  Yep it’s true, my death is before me.  Kind of exciting actually, though I’m not pretending it won’t be a bit of a rough ride.  After all, what has my spiritual warrior training been for if not to greet my liberation straight on.  I don’t call the news bad, but rather sad and soulful.  Let us cultivate souls together, my bro!

Thanks so much for your offer of veggies and mushrooms.  I would really like to take you up on the Ganoderma lucidum (oak Reishi).  Any other good cancer fighting mushrooms would be welcome.  We’re cooking up some blends for me.  .  Deep appreciations my bro!  I think I’ll pass on veggies for now, as I’m not eating any serious volume of food, but as fall comes on some greens might be delightful.  I know your food is filled with chi and want some, but am still settling into the complexities newly put before me.

Pretty exciting about the yuzu.  life wants to live, as I intimately learn as I am slowly gobbled alive.

My love to you and Diane,

the chuckster

Though I only saw Chuck a few times a year, every encounter resulted same pleasure and celebration of each other as Mere describes below. Fortunately my always perceptive partner Diane recognized the importance of capturing such camaraderie one of the last times we met up with Chuck and insisted on getting a picture of us. It, as they say, says it all.


(Meredith): Anytime there was a gathering of minds around food, plants, farming, or gardening, Chuck Marsh was there. (Patryk says: Mere is being literal here! A quick survey at the last Carolina Farm Stewardship Association’s Sustainable Agriculture Conference awards dinner revealed that only Chuck had attended all 31 of CFSA’s Sustainable AG Conferences.) When I  graduated from Warren Wilson College in 2005 and started working for the Organic Growers School, his name was on an unwritten but understood “list of names”- people who never expired as resources, teachers, idea-makers, movers and shakers in the grower movement. As I went about my work farming and non-profiteering, I committed those names to memory and was honored to call people like Chuck not only mentors, but also friends. When Patryk Battle (once another name on that same list and now a close colleague) and I sat down to write a tribute to Chuck, it occurred to us that the greatest impact Rascal Chuck ever had on us was less an effect of information, and more one of attitude.

Let me explain. People who knew Chuck probably won’t be surprised by this. Those who did not have the privilege of knowing him might misunderstand. Chuck Marsh was a wealth of knowledge about plants, the interactions between plants and people, plants and other beings, community dynamics, and much more. As a comrade of his who happen to also be obsessed with plants, I felt lucky to be able to email Chuck about a specific way to propagate muscadine grapes if I couldn’t quite remember, or recruit him to teach people about making willow tunnels. I’ll miss him for this, probably more than I yet realize. But the part of me that misses Chuck already and the most, is the subversive, over-activist, empath part. The part that connected with his attitude and his ethic and his hope. Indeed, sitting down to create a schedule for 2018 workshops at Living Web Farms, we brainstormed an epic series of Permaculture classes, taught by a cooperative of names and faces we have come to trust and love. Chuck was at the top of the list, and the topic Patryk proposed for him wasn’t water or soil or plant, but “Values and Ethics.” (Patryk adds: He was fiercely egalitarian, can do, and insistent that everyone and everything mattered.)

We are activists. So many of us who knew Chuck. We are subversive, probing, change-oriented people. Anarchists, herbalists, mothers with their boobs out, punk rock homesteaders, tax evaders, hippies, and outlaws. We are those society-as-we-know-it-is-a-rigged-spectacle type of people, with the tendency toward imagination and unfortunately, toward cynicism. Some of us have become angry. For me, (Meredith), the first time Chuck and I truly connected was when we were standing around talking to Joel Salatin at some event or another, and I quoted Machiavelli, and Joel faded away and Chuck and I sat at a round table in a mostly empty conference room and talked about how to maintain a revolution for a couple of hours. This is our type of person- the person who skips small talk about the weather and jumps to the cause and ripple effects of the weather pattern on the state of the top 4 layers of soil. Or something. But that’s not the point, that Chuck was our kind of person in that way. We all know this. The point is that he made being that way fun, even when being that way is sometimes hard, and annoying, and discouraging, and frightening.

He was always laughing, wasn’t he? So many people have said that since he passed, and it is true. That loud, hyperbolic guffaw-laugh. Why don’t we have a voice recording of it right now? Just for the people who didn’t know it well. That’s the point. In our line of work, and especially if your name is on the list of names that everyone calls to talk about muscadines or talk about revolution, it can be really hard to keep laughing like that. To remain hopeful, to not give in to despair, or anger, or sorrow. Especially now. When the world is on fire, and we need Chuck-like people the most, and there Chuck goes. Chuck who was always there. But Chuck Marsh left us better equipped than that. He laughed his famous laugh at the cynical jokes, but then he just kept attacking problems of epic proportions from a multitude of angles, from several different countries, with a dizzying web of people of all sizes, shapes, and colors. And he just kept on believing in that, connecting to it, happily, passionately. We could count on that. I could count on seeing him in the hallway at the next event and he’d be like “HEEEEEYY SISTER!” and give me a big hug and ask about my latest projects and boom around his thoughts, and then I’d wonder why in hell I wasn’t as convinced as Chuck was that I was doing important work. That I am doing the right thing. And suddenly I’d walk away and something would be renewed in the fight or the quest or whatever it is that moves us all to keep working. To keep hoping for change.

Another time I connected with Chuck was when he was immersed in a deep loss. We both were, and we sat together and asked “why?” and even in whirls of wisdom and knowing, there was a small sliver of time to support Chuck. Which felt rare and special. I went home and opened a letter a friend had sent me, and in it there laid a quotation. It said, “Be patient with all that is unsolved in your heart. Try to love the questions themselves.” I sent it to Chuck. It served me then, and it serves us now.

Thanks Chuck, for keeping it light. Thanks for believing. Thanks for being the kind of guy who could sit at a round table and sift through the ugly truth, but then just be happy and encouraged and overjoyed to make the world a better place. Missing that, wanting that back, well, that is a given. What we at Living Web would love to remember, is just to try to embody that. To do the work with joy. To laugh louder, even though you have considered all the facts. To believe that what we’re doing today is important. Because it is. To forget that would be to forget something that Chuck gave us. But to remember that. Well. That, dear friends, is how you maintain a revolution.

Elements of Cooking Series Next Class is about FIRE

“Heat is the element of transformation,” writes chef Samin Nosrat, who has worked with Alice Waters at Chez Panisse. Nosrat argues that heat, more than anything else, is what ultimately renders our food from one thing to another. “Heat is flavorless and intangible,” she writes, “but its effects are quantifiable.”

Long before Nosrat finished her recent book, Salt, Fat , Acid, Heat, (which I highly recommend), the culinary minds at Living Web Farms have been set on providing foundational cooking classes– free, accessible fundamental culinary knowledge to our local community and YouTube audience. This is why we have launched the Elements of Cooking workshop series.

The next class in the Elements series is all about heat. And more specifically, cooking with FIRE. It will be an exploration of the importance of mastering heat in cooking, but through the lens of understanding fire as the most primordial form of heat, and as a defining cornerstone in culinary culture. So, participants will be able to apply what they learn about heat to cooking using electricity or gas, but they will also walk away with a better understanding of fire cooking methodology, and a look into fire science from a cook’s perspective.


Elements of Cooking workshops explore the science and practical application of some of the most basic and axiological knowledge to mastering good cuisine. Our first event in the series centered completely on SALT, and in it we explored the origins of different types of salt, principals for using it, and practical but creative tips for salt’s role in your kitchen based on its chemical effect on foods. (Access the video here.)

For the fire class, I’ll be teaching along with Patryk Battle, as we explore the properties of wood, smoke, and fire and their affect the appearance, aroma, and flavor of food. We will learn how to tweak the culinary outcome of projects based on fire temperature, wood choice, and oxygen flow, along with timing and method of exposure. The class will be taught at our Kimzey Road farm, where we have a wood fired oven, and participants will learn to start and manage a fire for various projects. We will also use a homemade grill for demos, and plan to share several other more primitive fire-cooking methods, such as spit cooking, steam pit cooking, and cooking on a plank. Patryk Battle will share tips for wood fired baking as well.

The emphasis will be on simple, whole foods cooking, and we encourage people to come regardless of whether they feel 100% comfortable with fire. As a female in the culinary industry, it has been particularly meaningful to me to empower women and young people in grilling, smoking, and managing fires for cooking, and to introduce people who have never even started a fire to the excitement of this living cooking method. We will also cover the health considerations of fire-cooked foods, so anyone with concerns about health effects is encouraged to attend.

It is estimated that at least 3 billion people worldwide still cook over an open fire as their main source of heat. Whether you’re just dabbling in flavor mechanics, want to master fire cooking, or just want to have a few tricks up your sleeve when the power goes out, this Elements class will have a little something for everyone.

Future classes in the Elements of Cooking series include a focus on FAT, both plant- and animal based, and ACID, one of the most important components of well-composed cooking that many people overlook.

To sign up, visit http://livingwebfarms.org/workshops/elements-of-cooking-fire/

Earth-Coupled Cooling Tubes

by Richard Freudenberger, Living Web Farms Energy & Resource Coordinator


Earlier this year at Living Web Farms we completed a propagating facility for Black Soldier Fly (Hermetia illucens) larvae at our Grandview Farm. The Black Soldier Fly, or BSF, has a similar appearance to a mud dauber wasp but is not a nuisance to humans, nor is it a vector for disease.

A soldier fly larval colony is a very efficient composter of manures and organic materials, and the larvae themselves a source of protein-rich feed for poultry and fish. Residues from the colony can be applied as organic fertilizer, so the BSF production process is a quite sustainable and worthwhile undertaking for an agricultural operation.

The mating cycle of the Black Soldier Fly is active in temperatures between 24 and 37 degrees C (75 to 99 degrees F). In cooler environments they will simply go dormant but excessive heat can be detrimental or fatal, so in cultivation some type of climate control is necessary.

Our production facility is a modified 1,173 cubic-foot shipping container. The 20-foot cube was chosen because of availability, integrity of its unit construction, and long-term protection from the elements. These steel-clad containers are not at all designed for thermal efficiency, so we had to make modifications to amend that, keeping in mind the importance of passive energy design and long-term resiliency.

To ready the container for a suitable habitat, we insulated the interior walls and ceiling with 4 inches of extruded polystyrene (XPS) panel, which is not affected by moisture as expanded polystyrene is. The resulting insulation value of R-20 is a suitable balance between energy loss and available space inside, since the panels reduced interior volume to 880 cubic feet, or 75 percent of the cube’s original size.

A soil-covered living roof planted with a medicinal herb and a cover crop helps dissipate heat through evaporation, and water curtains on the southern and western exposures will activate should temperatures ever reach critical levels. Within time, growth from the jiaogulan herb and any subsequent plantings will overhang the walls exposed to direct sun, shielding the container’s steel skin in high-heat season.

But the main feature of passive climate control in the structure, and the subject of this blog, is a system of earth-coupled cooling tubes used in conjunction with a solar chimney that works to moderate airflow through the chamber to bring a temperate environment within.

Such cooling tubes, sometimes referred to as earth-tube heat exchangers, are lengths of ventilation pipe buried in the soil at depths between 5 and more than 12 feet. The depth, overall length of pipe, and number of pipes used are dependent on the structure, soil composition, and topography at the site.

In simplest terms, think of a box that has a long tube going into one end of it, and a short tube extending from its top. To get airflow moving through the box, you would either have to blow air into the long tube or draw air from the short tube. Both ends must remain open or flow cannot occur. If one end is blocked, air movement is stopped no matter how much you try to blow or draw through the tubes.

In our case, the long tubes are three 192-foot sections of 6-inch thinwall PVC pipe buried in parallel trenches at a depth of 6 feet. The pipes’ inlet points extend from the ground about waist-high at a 45-degree angle and are covered by a shading screen to avoid direct sunlight (and heat) exposure. The three exit points are near the top of the container some 60 yards distant, sealed tightly against the container walls.

Two of the three 192-foot earth-coupled pipe runs prior to being backfilled in the soil. Spacing is maintained between each tube to give the soil a thermal bank to draw from while subsurface temperatures recharge. Photo by R. Freudenberger

At the opposite end of the container a 10-inch diameter galvanized pipe extends vertically 14 feet from a sealed junction box welded into the structure’s roof. Surrounding the pipe is a rectangular metal frame lined with 2 inches of foil-faced polyisocyanurate insulation and covered with Sun-Lite HP fiberglass glazing.

This vertical pipe is a solar chimney which initiates airflow through the system. After about 10 am, when sunlight strikes the chimney’s south-oriented glazing panel, enough heat is absorbed by the black-painted galvanized pipe to induce a vertical draft. As the heated air rises, it has to draw from the air supply within the container, and as that supply moves out and upward, it is replaced by air from the buried tubes which is cooler, and denser, than the air it replaces.

A solar chimney induces natural airflow through the system, functioning on the principle that hot air rises. Photo by R. Freudenberger

This natural, passive flow continues as long as the sun shines, and naturally intensifies at the hottest part of the midday when solar radiation is greatest and when the greatest inside temperature reduction is needed. To assist flow during cloudy spells, we’ve installed a wind-driven ventilation turbine at the top of the chimney that allows greater free-flow than a simple cap and induces flow in wind velocities of less than 4 mph.

As an active backup, I felt it was necessary to include forced-air ventilation within the earth tubes and had to specify a fan that would not restrict the airflow of the passive system and would use a minimal amount of energy when operating. I located a 6-3/4-inch 38-watt metal axial fan with about 50 percent open flow that moved 198 cubic feet per minute at 110 volts AC. Three of these fans wired through an in-line thermostat pull cooled air through the buried tubes when the interior temperature reaches 30 degrees C (86 degrees F). Their amperage draw is low enough that a modest investment in a small inverter and solar panel would get the system off-grid.


A fan-driven backup system is in place, which only activates when interior temperatures rise above 86 degrees F. The axial fans allow ample free flow when not powered. Photo by R. Freudenberger

The concept of cooling tubes is easy to comprehend but not so simple to put into practice. The notion that the soil below two or three feet depth maintains a 50 degree F temperature year-round and worldwide is both wrong and stubbornly persistent. The actual equilibrium depth is likely closer to 20 or 30 feet, and the site latitude has a significant impact on mean temperatures, along with soil composition and vegetative growth on the surface.

Seasonal soil temperature change related to depth below ground surface for moist soil. Image courtesy Virginia Tech

From a practical standpoint, designing a functional earth-coupled ventilation system is a compromise of several factors, not the least of which are the cost of excavation and materials, the flexibility of the site plan, the difference in temperature between ambient outside air and the target goal, and seasonal requirements.

In our situation, we had a specific footprint for the cooling tube field, dictated by an earthen bank along the southern side and our biochar facility at the north, which left about 15 feet of width and a 60-yard open run that is also a vehicle access. Because we were installing a retaining wall at the bank, excavation equipment was available, so some cost was defrayed.

While heat capacity of soil is significant, its conductivity is not. The tubing material is not so critical other than its structural qualities (the PVC we used has a crush strength of 3,000 psi) and its ability to conduct thermal energy. When considering metal and concrete, cost goes up, as it also does when larger diameter pipes are used.

We used 6-inch diameter thinwall drain pipe because it’s very common and its surface area over the nearly 600 feet of run provided enough residency time for the air to absorb coolth on the pass through. Larger pipe (20 inches in some cases) is more common in commercial projects, but expenses increase drastically with size.

Another way to increase surface contact is to increase pipe length but at some point the resistance to airflow becomes a problem and forced-fan flow is needed, a situation which we view as backup only. Another option is to add more pipe runs and keep them shorter, but our field was too narrow to allow the 5-foot spacing between pipes needed to maintain the thermal storage bank that the tubes draw from.


Outlet temperature in Fahrenheit from one of the cooling tubes measured on a 90.5 degree day in late summer. Photo by R. Freudenberger

A legitimate concern with any earth tube installation is the accumulation of condensation in humid climates. For the fly larvae, this is not an issue since their environment is already fairly humid with food scraps and moist residues. In the event that moisture builds up in the floor of the tubes, which has not occurred so far, we’ve included standpipes at the lowest end of the runs so we can pull any water buildup out from the surface with a small suction pump.

Earth-tempering principles also apply in the winter. When outdoor temperatures are far below what’s needed to keep the insects active, the relatively warmer air from the tubes tempers the inside environment. More significantly, the container was placed alongside our biochar facility which generates a substantial amount of hot water in process. Our biochar crew installed a radiant floor heat system in the concrete floor we poured over the subfloor of the container, so the soldier fly facility can readily tap off the hydronics for heat any time it’s needed.

The earth-coupled tubes are only part of the bigger picture of soldier fly production, and as we develop and improve our propagation system we’ll host workshops to share what we’ve learned about breeding and using the black soldier fly, and applying resilient technologies to that purpose.

New Water Management Earthworks Increases Resilience at LWF

By Patryk Battle, Living Web Farms Director

photo courtesy of John Henry Nelson

Part of Living Web Farms mission is innovation with the goal of ever increasing our land’s and our farming operation’s resilience. Over the course of the last year or so we’ve undertaken several new projects with this end in mind. In the future, I hope to describe some other innovations such as our soldier fly production unit and our passively aerated windrow composting system. But for now, I want to cover the most ambitious and for certain our largest innovation/installation.  This is our Grandview Farm’s extensive new system of water management earthworks, conceived, designed, and installed by John Henry Nelson, of the Stone and Spade Permaculture Design and Installation Company. This project started with our original concept, which was to install a pond that would collect water from the extensive roof area covering the Grandview Biochar and Greenhouse Complex. Expanding on this concept John designed a water management/wetland plan for the entire Grandview property. Over the last year, he has installed three major ponds, a couple of small settling ponds and a remarkable system of swales and berms and wetlands which collect, filter and channel almost all of the rainwater that would otherwise run off our land during major rain events. The system is anchored by a million gallon Collection Pond next to our greenhouse. Fortuitously this placement puts the Collection Pond at the lowest place on the property.

The windmill at Living Web Farms. Photo courtesy of John Henry Nelson

Protected by a wetland installed between this pond and the biochar facility’s parking lot this pond includes a fish lock to facilitate the harvesting of fish. Our new Collection Pond receives the water collected from the roofs of the biochar greenhouse complex, and the above-described swale berm wetland system. The Collection Pond is projected to collect over a million gallons a year. Another key component of this system is a “Saddle” Pond. Situated at the highest point on the Grandview property, the “Saddle” Pond likewise, has a million gallon capacity. John’s installation connects the Saddle Pond by an underground pipeline to the Collection Pond. Using a windmill and a backup solar powered pump his system moves water from the Collection Pond up to the Saddle Pond. From the Saddle Pond, water can be distributed by gravity to all of the plant and animal operations on our Grandview farm.

There is a third pond installed in a 3.5-acre field which is separated from the main property by Grandview Lane and therefore must have an independent swale-berm pond collection system. This pond has a capacity of approximately 100,000 gallons. This pond is connected by a pipe that goes under Grandview Lane to the Saddle Pond. Our always industrious, creative and inspired biochar crew has already created a mobile solar power unit which will be able to power a solar pump for this more remote pond. We will use this pump on those occasions when the hundred thousand gallon pond reaches capacity, and we need to move excess water to the Saddle Pond.

Installed at a level grade, the swales are designed to first and most importantly channel water into the aquifer. Previously during intense rain events, water rushed off our property and even possibly at times contributed to downstream flooding. Since our swales have no slope water only moves gently to the Collection Pond when the water holding capacity of the land is exceeded. Such saturation causes the swales to fill up . The end of the level grade swale system furthest from the Collection Pond has no outlet. Only the end of the swale system closest to the Collection Pond has an outlet. Once the swales have filled during excessive rains, they must overflow at this end through a small settling pond, which then overflows, channeling the water through a wetland installation down to the Collection Pond.

Since the fields at Grandview are all covered by either pasture, or in the case of the 3.5-acres multi-species no-till planted cover crops/vegetable crops, there is virtually no erosion. However, during intense rain, there will always be some stripping of small amounts of topsoil and organic matter. The swale/ settling pond component of this system is designed to intercept this bit of erosion before it leaves the property. Hence the swales will become increasingly rich, as they gather sediment and we will be able to harvest sediment from the settling pond. Furthermore, the berms will stop wind blown leaves each fall. These leaves will settle into the swales further enhancing the fertility of the swales. Water tolerant plants such as Silphium Perfolaitum or Cup Plant can be planted on the uphill side of these ever more fertile swales, and they will eventually colonize the swales converting the captured fertility into superior animal forage. Meanwhile, because so much water is channeled directly beneath the berms, they are ideal sites for silvo pasture plantings.


A swale after heavy rainfall. Photo courtesy of John Henry Nelson


So far we have installed mulberries, alders (they fix more nitrogen than legumes, and their leaves are excellent forage for animals) apples, pears, persimmon, pawpaw, and serviceberry. This initial planting is only a beginning. Eventually the berms will be a diverse collection of human food and animal forage crops, inter planted with bio- accumulators such as comfrey, medicinal plants such as yarrow, and culinary herbs such as oregano. We will also, as always, plant a great diversity of farmscaping plants and pollinator habitat.

A swale, flanked by diverse cover crops for our sheep to graze. Photo courtesy of Meredith Leigh

With regards to the fruit plantings, we have intentionally planted more than we are likely to be able to keep up with harvest wise. Our hope is that by creating great abundance, we will ensure that we get fruit despite bird and squirrel pressure. Also, the fruit we miss which drops to the ground will be relished by our grazing sheep, chickens, and cattle.

Since the ponds are not yet ready for stocking, and I have no expertise in the realm of aquaculture, I’m not going to attempt to describe this piece in any detail. I can however reassure readers that we will not be feeding Purina Fish Chow or any similar products to our fish. To train the fish to the fish lock, we will regularly feed them small amounts of soldier fly pupae in the fish lock. Otherwise, we will be stocking only modestly with fish species that naturally occur in our region’s pond wetland systems. For the most part, the fish will be left to rely on the natural pond/wetland food web for their sustenance. Their populations should expand as the pond ecology deepens and diversifies. We will be planting the pond edges with this goal in mind.

Hard to imagine? You don’t have to. On Saturday, August 19th John Henry Nelson will be presenting on Permaculture Earthworks and Farm Wetland Ecosystems here at Living Web Farms. Weather permitting, this will include a tour of the entire system of ponds,wetlands, swales, berms, windmill and plantings. To register and to learn more, click here.

I’m looking forward to it and hope to see you there!

Closing the Loop – Biochar as Carbon Negative Technology

By Dan Hettinger, Biochar Facility Manager

The increase in annual global carbon emissions has stalled in recent years despite strong global economic growth.  In effect, economic growth is no longer coupled with increased carbon emissions.  In 2015, most of the world agreed that we can limit climate change to a rise of 2 degrees Celsius. This is all great news for everyone, especially those who are most impacted by climate change.  However, some say that the 2C goal is unattainable without the use of technologies that actively remove carbon from the atmosphere.

Biochar production has been recognized as one of these carbon negative technologies.

Biochar is biomass that has been carbonized through a process called pyrolysis, rendering its labile carbon in a more stable form. When added to soils, this stable, recalcitrant carbon is resistant to decay, and has the potential to sequester carbon much longer, potentially for thousands of years.  For those that have followed our work here at Living Web Farms, you know that with the help of our friends at Chargow, LLC we’ve talked about this before.

We all know plants take in carbon dioxide in a process called photosynthesis, and this carbon is released when these plants are burned.  What might not be as apparent is how most of the stored carbon in dead material is slowly released back into the atmosphere through eventual decay.  This is where pyrolysis comes in.  Instead of being piled up and burned, or left in the field to rot, waste plant material is diverted into an oxygen limited chamber, called a retort. Here, through the application of heat, complex molecules present in the biomass are broken down either into gasses that can be easily condensed as wood vinegar, tar and bio-oil, or non-condensable gasses that be stored or burned for heat or electricity.  Leftover from this process is a high quality lump charcoal that we call biochar when it’s incorporated into soils.

Collecting “slab wood” at a local sawmill. This stuff has little commercial value. Some mills sell it as wood chips, others pile it up and burn it.

For years now we’ve been making biochar in batches with wood waste from local mills.  We use a 14’ diesel flatbed for pickup and local shipments, an LP forklift, our share of gasoline small engines and a fair amount of electricity running various blowers and pumps:  these are carbon heavy tasks we do on a regular basis.  In light of this, we wanted to know if we could still claim to be a carbon negative operation.

Determining a carbon footprint requires a detailed look at the throughput of the facility – what goes in and comes out – including all the hidden sources of carbon usage (down to the RTV silicone we use for gaskets). Life cycle assessments (LCA) are used to inform decisions on improving sustainable production practices. LCAs are consulting tools used to shed light on a product’s environmental impact from raw materials extraction, through processing, maintenance and eventual disposal.  Third party sustainable manufacturing consultants Verified Life Cycle, Inc., from the front lines of the hemp industry,  were able to modify their models and perform a cradle-to-grave carbon life cycle assessment for our biochar facility.

Verified Life Cycle, Inc., analyzed our process: from the transportation of raw materials, fuel inputs and energy exchanges at our facility, and shipment of finished product to our farms.  It’s important to note here that we are relying on early data from biochar production methods that may be challenged as biochar gains relevance in the global carbon marketplace.  Particularly of note is the pyrolysis process itself, where ever changing quantities of non-combustible carbon dioxide account for a significant portion of the total gas generated.

A site visit in January of this year revealed:

This means, at present, we may sequester up to 4 lbs carbon dioxide equivalent for every 2.2 lbs of finished biochar.  Our average yield of 7 400 lb batches of biochar/week means it’s possible we sequester 5,189lbs of carbon every week.  To put this in perspective, I drive nearly 60 miles round trip (I know) just to get to work. The EPA tells us the average car emits 441 grams CO2/mile, so at 60 miles, I emit about 58 lbs carbon just getting to work (about 5% of our total carbon sequestered over the course of a week).  I’ll mention that electric cars typically emit about ⅔ less carbon emissions.  For someone like me, who commutes just within the range of most electric cars, this is an increasingly obvious choice.

Let’s look at our operation in a little more detail:

  • Carbon sequestration is possible when considering stored carbon in the trees themselves.  It’s best to leave the trees alone to continue pulling in atmospheric carbon.
  • When hardwood and softwood waste is diverted into our process, some of the original stored carbon is transformed into sequestered, recalcitrant carbon.
  • Transportation is a huge part of our carbon footprint.  In the short term, we’ll be switching our diesel trucks to run on 20% biodiesel.
  • Even though our inputs are nearly 50% hardwood, their value in sequestration is significantly higher.  As producers, we can prioritize collecting hardwood waste when possible.
  • Our electricity inputs are not negligible.  We can shave electricity costs through efficiency measures, then further explore our options with generating our own power via solar PV, syngas generators, stirling engines, ethanol fuel, or small scale steam.

Processed biochar is stored in large woven polypropylene bags like this before shipment to our affiliate farms. These bags are made in India – literally the other side of the world. Since learning of the carbon impact of shipping these, we’ve switched to a different style bag that can be easily reused in the field up to 5 times

It’s worth noting there are other carbon negative technologies, some more accessible than others. Though simple carbon negative technologies and carbon smart farming exist, these practices can’t be seen as a license to pollute.  For farm scale biochar producers like us, this means paying attention to the subtleties of carbon farming on all fronts.  It’s likely that small scale producers have an edge here. Farmers and enthusiastic homesteaders have a real opportunity to achieve carbon negative through the use of simple ‘backyard biochar’ technologies like the TLUD, Tin-man and Kontiki kiln.  These systems can use common landscape wastes generated on your own property: limbs, chips, sticks, as feedstocks for high quality DIY biochar.  Transportation, processing, electrical, and application inputs are practically null when biochar is produced on a small scale from feedstock generated and applied on site.


Processed Biochar from Living Web Farms

To me, most fascinating of all is the role of biochar applied in the soils.  In soils, biochar has a cascading effect where microbes (carbon) take up residence in its micropores, cycling more nutrients, processing organic matter (carbon) and facilitating the growth of mycorrhizal fungi (more carbon!)  Improved soil fertility means more trees survive, ecosystems are healthier and we’re more than one step closer to that 2C goal.