Climate Impact

We use All Power Labs’ gasifier gensets to produce the biochar. There are no fossil fuels involved.

Ignoring gasification for a second, not even conventional charcoal retorts use fossil fuels; the volatile fraction of the charring wood, which comes off as wood smoke, is combustible, and is recirculated to provide heat for charring the rest of the wood. Charcoal retorts are ignited by burning a little wood, then burning a lot of smoke—all derived from the wood that the retort is turning into charcoal.

Here’s the process we use to make char in the process of producing a clean-burning gas that is used to generate electricity via an engine:

Biochar is not sequestering CO2; it is sequestering carbon itself. Making solid carbon, and taking it out of the carbon cycle by burying it in the ground is akin to “reverse-coal mining.” Since the mining and burning of coal (and other fossil fuels) is what contributed the bulk of the CO2 in our atmosphere, sequestering carbon is what is needed to fix the problem.

Note that we’re emphasizing the sequestration of *carbon*, not carbon dioxide. If you sequester carbon dioxide, every carbon atom you take out takes two oxygen atoms with it. Carbon dioxide, in gaseous form, is prone to leaking if you sequester it in caverns, and geological events can release it as well. Carbon dioxide, sequestered in minerals such as various carbonate minerals, is only possible at very specific locations where the geology permits it. But sequestering carbon in the form of biochar can happen anywhere there is soil.

Charcoal (which is basically what biochar is) consists largely of carbon that is *recalicitrant*; it is not biologically active and does not revert to the atmosphere as CO2 without combustion. The half-life of the decay (as in returning to the carbon cycle, not radioactive decay) of carbon in this form is measured in hundreds to thousands of years. This is not a *temporary* removal of the carbon from the carbon cycle system; this is removing carbon from the carbon cycle for time periods considered on the geologic time scale.

When you char biomass the burning process releases its volatile carbon fraction but the fixed carbon is instead converted into char, and the char is essentially taken out of the carbon cycle because it does not revert back to carbon dioxide unless it is combusted. The labile fraction of this char takes decades to decay, and the recalcitrant fraction essentially does not participate in the carbon cycle at all.

Contrast that with mulching; mulching leaves the biomass to decay and decompose. Most folks aren’t aware of this, but when biomass decomposes, virtually all of it reverts to carbon dioxide within a couple of years. Also, it is not true that more nutrients are saved compared to pyrolyzing the biomass into char; the mineral fraction of woody biomass does not vaporize; it remains as ash in the char.

What pyrolysis does is vastly increase the surface area and porosity of the substrate biomass, making more habitat for soil microbes, increasing air and water permeability, and turning the biomass into chemically adsorptive charcoal, which then participates in nutrient exchange all while not being consumed as part of the carbon cycle.

In the field of soil science, the number of scholarly articles on biochar overtook the number of scholarly articles on compost roughly two years ago, and it is only accelerating. This is because biochar has been found to be broadly applicable with many agronomically beneficial effects.

Up to a point, yes, but too much CO2 does not. Here is an article from Scientific American that explains why. Increased CO2 concentration in our atmosphere also harms the nutritional value of our food crops. Our crops appear to produce more sugar when CO2 is more concentrated. This article discusses the possible causes and impact of these changes: Politico.com: The Great Nutrient Collapse

Given that the primary carbon-bearing gas in the atmosphere is carbon dioxide, even scientists will occasionally refer to CO2 in shorthand as “Carbon”.

Plants uptake carbon dioxide (CO2), and release oxygen (O2). Even though the oxygen plants release actually comes from water, and the oxygen from CO2 is indirect in its route to becoming O2, this is still a net removal of C (Carbon) from the atmosphere while increasing the O2. Therefore it’s actually accurate to say that plants take Carbon out of the atmosphere.

Our method of producing char is strictly to use waste biomass. It is neither cost-effective nor environmentally friendly to cut down fresh trees to make biochar. We’re not doing that, nor would we advise anyone to do that. There’s more than enough waste wood from prunings and dead trees to supply us with feedstock.

California currently has a tree-mortality crisis; the forestry service cuts down the dead trees, and either leaves them to decompose or disposes of them in controlled bonfires, which produce high levels of pollutants but are safer and cleaner than uncontrolled forest fires fueled by the dead trees and consuming surrounding healthy forest as well. Our alternative to this is the use of these dead trees as feedstock for producing energy and biochar. No trees are harmed in the obtaining of the feedstock we use to produce biochar.

This list of 100 drawdown solutions lists biochar at #72. But the thing that is distinctive about biochar (when produced in the course of generating power with biomass) is that it removes carbon from the carbon cycle while producing renewable energy, and continuing to add drawdown value by enriching the soil and reducing nitrous oxide emissions, a greenhouse gas 298 times more powerful than that, by 10-90%. This conjunction of several benefits is what makes biochar compelling as a solution. Biochar is not, by itself, a comprehensive solution to the climate problem, but the role it plays in removing carbon from the carbon cycle is particularly valuable: Drawdown.org: Food Biochar

Aggressive tree planting is necessary, there is no doubt about that. However, taking carbon out of the carbon cycle while improving the soil absolutely has a role to play. Planting a tree isn’t enough if the soil is depleted or isn’t retaining water well. Biochar can help restore the soil’s fertility, which can help make soil resilient against some of the threats facing trees.

There is a serious tree mortality crisis in the western United States right now; this shows that established trees can die and return the carbon content embodied in them right back to the carbon cycle. On our part, our method of taking biomass waste and carbonizing it at the very least removes a large portion of the fixed carbon from the feedstock from the carbon cycle. Much of our feedstock comes from trees that have died due to drought or climate-change-related reasons. If this biomass were simply left to decompose, all of that carbon would be back in the air within a few years.

Please consider the case made by Dr. Johannes Lehmann of Cornell University. It’s not biochar instead of planting trees; it’s biochar to take biomass waste and remove the fixed-carbon fraction of it from the carbon cycle.

We concur on the matter of animal agriculture being a huge exacerbating factor for climate change, given that 83% of the large scale farming in the world is being used to produce feed to support animal agriculture, whereas animal products only provide 18% of the calories eaten worldwide. Switching to a plant-based diet would result in a massive net reduction in large scale farming. Vegans simply do not eat anywhere near as much plant material as livestock. Replacing meat with beans and greens is hardly as impactful as feeding 12 times that amount of food to an animal to produce the same weight of meat.

Map showing livestock use

Here’s a breakdown of how we use our land by Bloomberg. Observe that the amount of land we use for raising animals *vastly* outsizes the land we use to raise our own food crops. Look at the amount of land we use for livestock feed and feed exports compared to what we use to raise our own food crops. Yes, vastly reducing if not eliminating animal agriculture is one of the biggest impacts we can make, greater in impact than the entire carbon footprint of the transportation sector.

Even if you start with vegan diets, why stop at that only? Reducing animal agriculture only addresses emissions. It does not address the question of how to deal with the CO2 emissions that are already in the atmosphere. CO2 may not be as potent as methane and nitrous oxide, but it is, by sheer volume, the biggest contributor. Biochar has a significant fraction of its carbon in the form of recalcitrant carbon; it does not decompose nor revert to carbon dioxide but behaves more like a mineral. Unlike the carbon in compost, which all reverts to CO2 within a year or two, recalcitrant carbon in biochar is essentially sequestered, having been taken out of the carbon cycle. But while doing so, it can enrich the soil and offer compelling agronomic benefits. See this article by Dr. Johannes Lehmann.

By making recalcitrant carbon and burying it in the ground, the production and use of biochar is analogous to “reverse coal-mining”. Since the mining and burning of coal was one of the biggest factors contributing to climate change, it would seem to us that a productive reversal of this would have to play a role in fixing the problem.

This is not a matter of biochar vs. other solutions; we need all hands on deck to address the matter of the climate crisis.

This is our Carbon Accounting Spreadsheet and a research paper: Sustainable biochar to mitigate global climate change (Nature Communications volume1, Article number: 56 (2010))  as well as an explanation on our Local Carbon Network page. This solution can make a significant impact and be used in conjunction with other drawdown solutions.

No, we do not – we use the wood in a process called gasification to produce the biochar and no external electricity or heating is required. The heat comes from burning the smoke (tar gases) that comes off of the wood as it chars. Our char is not made in a way that wastes the energy; our char is the co-product of a biomass gasifier. We take biomass waste, generate electricity and heat from it by using a gasifier genset to produce a gas from the biomass which we burn in an engine to generate electricity.

The process of burning the off-gasses from the charcoal-making process does release some CO2 (but no methane), however, because plants obtain the carbon in their structure from carbon dioxide in the air, this process is still carbon neutral because whatever carbon is released had been recently pulled out of the atmosphere, whereas the carbon released from fossil fuel sources had been out of the carbon cycle for eons.

The char itself, if used as biochar, is taken out of the carbon cycle (since unlike wood, the bulk of the carbon in charcoal does not decay and revert back to CO2); making solid carbon and burying it in the ground is akin to “reverse coal mining”.

It is unlikely. The transition to renewables seems ever closer. See the articles by Motherboard and by Altenevo. However, it is not sufficient to stop the increase of the use of fossil fuels; the use of fossil fuels needs to decrease to near zero, and carbon must be removed from the atmosphere to address the problem. The consensus reached at the Paris climate accord of limiting the temperature rise to 1.5˚C cannot even be reached without vast quantities of carbon being removed from the atmosphere.

This is why it is important to include carbon-removal technologies in a comprehensive climate change solution. See this Economist article for details on why it is not sufficient to cut emissions. There is already far too much carbon in the atmosphere. Carbon removal is absolutely necessary.

It depends on the problem. Hemp cultivation does not address the problem we are trying to solve. There are many hemp enthusiasts who believe this to be an effective climate change mitigation strategy but it is not. Hemp may be a less environmentally damaging crop for producing paper pulp and fiber for fabric, but like any agricultural product, its waste products still decay and release their carbon content into the atmosphere.

Making biochar from any suitable agricultural waste would take the fixed carbon content of that waste out of the carbon cycle, regardless of what that material is. Hemp cultivation simply does not address the same problems biochar addresses.

No. This question has the implicit assumption that biochar requires wood as feedstock, and that this wood must be obtained by cutting down trees for biochar. This ignores the massive quantities of wood waste from the lumber industry and the agricultural biomass waste stream which is just as fit for producing biochar.

The sustainable production of biochar, in the long run, must be done from agricultural waste. As long as mankind carries out agriculture, one pattern will be constant: tremendous quantities of biomass, far outweighing the quantity we harvest for food, will be produced as waste. Prunings from trees, grain chaff, corn stover, straw, husks, stems, old canes from vines, shells from various nuts, etc. all can be feedstock for biochar. Currently, our machines focus on woody biomass, although the R&D team is looking to increase fuel flexibility. Today non-woody feedstocks can still be charred and even if they cannot be used in our equipment to make electricity, they can still be used for heating and cooling of water, greenhouses and other applications.

What we’re trying to bring people’s attention to is the fact that there already exists a carbon capture system of global scope that captures massive quantities of carbon— agriculture!

We are not the ones who originally came up with the concept of using biochar as a way to park carbon in the soil. Johannes Lehmann, the Cornell soil scientist, originated this idea as described in paper: Sustainable biochar to mitigate global climate change (Nature Communications volume1, Article number: 56 (2010))

The impact of biochar is not merely from the carbon taken out of the carbon cycle by the recalcitrant fraction; it also increases the part of the carbon cycle that is not in the air via the increased capacity of soil to hold on to plant exudates (green carbon), which then support fungal mycelia (white carbon). Roughly speaking, and depending largely on the initial soil quality, an increase of one unit of black carbon supports an increase of ten units of green carbon in the soil on an ongoing basis and ten units of white carbon that develops by consuming the plant exudates. A large portion of carbon that is temporarily parked in the soil, even though it may still be in the cycle, will nonetheless help reduce the CO2 in the atmosphere.

Biochar was evaluated and ranked by Drawdown.org as being in the top 100 things that could be done to fight climate change. Their estimate is conservative and does not appear to account for the reduction in N2O (nitrous oxide) emissions caused by biochar.

To review, N2Ois a gas, which is released from soil and compost through denitrification of nitrogen added as fertilizer, that is 298 times worse than CO2. This is a huge source of greenhouse gas emissions from industrial agriculture. Biochar prevents the loss of nitrates to nitrous oxide, while the denitrification that does occur takes the route of becoming N2, which is harmless. While reducing denitrification, biochar also makes these captured nitrates available for plant use. Enhanced plant growth and increased plant exudate activity then captures even more CO2 in the form of soil carbon.

This article describes the process in detail: Plant growth improvement mediated by nitrate capture in co-composted biochar  (Scientific Reports volume5, Article number: 11080 (2015)).


Local Carbon Networks

You can start by putting together the right network of local partners; a waste wood source, a community garden, and a site where you can put the conversion equipment and use the energy and heat produced. You can contact us for coaching.

The conversion equipment will offset fossil fuel by producing electricity and heat from biomass. As it runs, it converts some of the carbon that was in the biomass into biochar. At full power (25kW electrical and 50kW thermal), the biochar output which is about 1.5kg per hour. Each kilogram of biochar has a potential climate impact of 20-40kg of CO2e (the “e” stands for “equivalent” of the CO2 heat-trapping effect in the atmosphere), some from the fossil fuel offset, some by preventing the emission of other greenhouse gases, such as methane and nitrous oxide which would be emitted if the biomass were to decompose naturally, and finally some by the sequestration of the biochar in soil along with its impact on soil fertility.

Our equipment, running 20 hours per day for 300 days per year, at this 1.5kg per hour rate, will therefore generate 9 tonnes of biochar in a year, while also generating 450,000 kWh’s of energy. All of these figures can vary depending on a number of factors, but if we use the middle CO2e figure (30kg CO2e per kg biochar) we get 270 tonnes of CO2e impact. For comparison, it would take approximately 12,000 trees to absorb the same amount of CO2 in a year.

LCN partners can be private companies, municipalities, non-profits or any combination of these. Funding can be by sponsorship, loans, grants, crowdfunding, or donations. Non-profits have an advantage in that donations are tax deductible. Crowdfunding can be a lot of hard work but if there are 3-4 partners with sizeable mailing lists it can be successful.

Any untreated wood is fine, such as tree trimmings from a municipality or utility’s urban tree maintenance, prunings from local farms or orchards, also some agricultural byproducts such as nutshells, as well as logging or forest-thinning slash, river bed cleaning, lumber mill and construction waste, etc.  You may want to start by seeing if you have any green waste recycling yards in your area or by speaking to your municipality or local farms.

The only requirement is that they have, or are willing to set up, a composting operation.

Due to the impact of transportation fuel and costs, the closer the better. We’ve found keeping everything within a range of 10 miles to be very efficient.


The char is a co-product of biomass gasification. Biomass gasification produces a clean burning blend of gases that can be used in an engine to generate power. In the process of producing gas, the biomass is turned into charcoal. A portion of the charcoal is used to “unburn” the combustion products of burning the wood smoke, producing the gas that is then re-burned in the engine. This “unburning” reaction is known as “reduction”. All of the remaining charcoal from this process, which comes through the very high-temperature processes involved in gasification, is what is used as biochar. The high-temperature processes result in chemically stable charcoal with very high surface area.

We are using All Power Labs’ biomass gensets to make this work, because we generate renewable electricity and heat while making the biochar – it makes it cost effective and has climate impact.

See the explanation of the process of gasification on the ALL Power Labs website page and the image below of the final stage of the process called reduction (scroll up on this document for the image of all the stages)

Not entirely. The ash from your fireplace is what’s left over when all that can be burned is consumed in the fire. The stuff that is left in your fireplace—that grey powder ash— is mostly oxidized minerals with some bits of charcoal in it. Our material is the other way around; it is mostly charcoal with some ash in it.

A large portion of the ash from burning wood is potassium and sodium oxides, with the remainder consisting of magnesium, calcium, and other minerals. These tend to be very alkaline. Our biochar has some ash in it, but it is over 80% carbon. It is not nearly as alkaline as straight ash.

Using ash from your fireplace does not sequester carbon the way using charcoal does. Charcoal also has the added benefit of remaining in the soil for the long term to contribute to nutrient exchange (IF you mature it properly by sending it through the compost or charging it with soil microbes), whereas the minerals in ash get consumed by the plant.

Our char is alkaline when taken straight from the bucket simply because there is some ash present; that is true. However, using raw char like that is the wrong way to use char, and in all cases, each gardener or farmer needs to determine whether the soil and the crop are appropriate for using biochar.

The proper way to use biochar is to mature it with compost. In many cases, compost benefits from liming. Compost has a lot of bacterial fermentation processes going on, and bacterial fermentation tends to produce acids (for example lactic acid fermentation in pickles and sauerkraut, acetic acid production by acetobacter in vinegar etc.), and these acids react with the alkaline minerals in biochar (potassium, magnesium, calcium—all of which are plant nutrients), and neutralize the alkalinity while making these available for plants as nutrients. I

If you properly mature biochar this way, it behaves like compost, and is not likely to raise the pH of neutral soil. If your soil is acidic, compost raises the pH by virtue of buffering. Compost can also lower the pH of alkaline soil for the same reason.

The short answer is “hundreds of years.” Here is a study published from Wiley Online Library describing how higher-temperature biochar decomposes more slowly than low-temperature biochar – ours is the high-temperature type. The labile fraction will take decades and the recalcitrant fraction will take thousands of years.

Our char is a blend of the two chars indicated in the screenshot of the lab test I attached here. We use char from the PP30 gasifier genset produced by All Power Labs. Our blend is 9 parts of the ACV char—coarse charcoal from the char-ash collection vessel— to 1 part of the CCC char—fine charcoal dust that is separated from being entrained in the gas at the cyclone catch-can.

Please note that the CEC (Cation Exchange Capacity) of the raw char is not going to be nearly as high as the CEC of char that has been properly matured by co-composting. (Namely wetting the char down, mixing it with material to be composted and letting it go through the decomposition process.) The CEC boost from co-composting comes from weak organic acids that are produced during the decomposition process, since the conjugate bases of weak organic acids are the actual sites where cations are exchanged in lieu of the hydrogen ion released from the weak organic acid when it comes in contact with moist, mineral-rich soil. The CEC of the raw char is going to be orders of magnitude lower than a matured char which is loaded up with these decomposition products.

Note that that bacterial fermentation tends to produce acids, such as acetic acid via acetobacter in the production of vinegar, and lactic acid in lactic acid fermentation that occurs in the production of yogurt and sauerkraut. In compost, there’s a tremendous amount of bacterial fermentation going on, and these weak organic acids which end up bonding to the char are what really increase the CEC.

Copy of soils lab report

Yes, absolutely. Actually, it does this phenomenally well. These photos we took of informal experiments at Gill Tract Farm show the plants in the biochar raised bed to have rich green leaves and be much more robust than those grown with plain compost. High access to nitrate is necessary for leaves to produce that kind of growth.

a pumpkin plant in soil
Pumpkin plant that has received biochar compost

a small pumpkin plant
A pumpkin plant that has received compost without biochar

Biochar does better than storing NO3 (nitrate); it prevents denitrification, where NO3 converts to N2O (nitrous oxide), which is a pollutant with 300 times the greenhouse gas impact of CO2. As a result of capturing NO3 from decay processes, and releasing the NO3 to the plants as nutrients, biochar that has been sent through the compost (as we recommend) has a double impact:

  1. Reduces the natural N2O emissions associated with composting by up to 90%.
  2. Makes abundant NO3 and more available to the plants.

Here are two scientific studies that back up this up. First:

Plant growth improvement mediated by nitrate capture in co-composted biochar
(Scientific Reports 
volume 5, Article number: 11080 (2015))
Excerpt from the above study:

Plant growth study
Compost addition and a higher fertilization significantly improved plant growth in all treatments (Fig. 2, Table 2). However, adding co-composted biochar always caused the largest plant growth increase (Fig. 2). The relative plant growth stimulation with BCcomp, within the respective compost-fertilization treatment, was the stronger the lower the overall nutrient supply level was, ranging from 139% to 305% of the respective controls (Fig. 2).

In layman’s terms, they saw an increase in output between 139% and 305% for quinoa grown in soil that had been amended with composted biochar (note that the sample here is given a variable name BCcomp, for “BioCharcompost”. They also describe how Water holding capacity was significantly improved. Another excerpt:

Water holding capacity and initial N retention
The addition of either compost or biochar significantly increased the WHC of the poor sandy soil mixture (Supplementary Fig. S3. BCpure and BCcomp increased the WHC, and when applied together with compost, BCcomp was significantly better than BCpure, ranging between increases of 10 and 15%, respectively (Supplementary Fig. S3).

They report that bare, un-composted biochar is better at capturing nitrate and preventing it from entering groundwater, but composted biochar, having already captured nitrate from compost, is better for delivering it to the plants. If one’s objective is to help the plants as much as possible, use composted biochar. If one is strictly interested in capturing nitrate, put raw biochar under or downstream from where nitrate containing run-off is coming from. However, be aware that raw biochar will reduce plant growth by up to 60%. This method of application is not good for the plant, and is strictly for nitrate pollution control.

Second, this related article in the same journal by other authors on how biochar reduces N2O emissions:

Biochar and denitrification in soils: when, how much and why does biochar reduce N2O emissions?
(Scientific Reports volume3, Article number: 1732 (2013))

Layman’s summary of this is that biochar prevents the loss of nitrate (NO3) while holding on to it, and that which is denitrified decays to N2 rather than N2O.

Yes. Don’t add biochar after anaerobic digestion; add it before. Biochar that is conductive (that is, biochar that has gone through a process in excess of 800˚C) significantly improves the production of methane from anerobic digestion.

See this scientific publication on the matter.
Enhancing methane production from food waste fermentate using biochar: the added value of electrochemical testing in pre-selecting the most effective type of biochar
Cruz Viggi et al. Biotechnol Biofuels (2017) 10:303 https://doi.org/10.1186/s13068-017-0994-7

This happens because there is a process bottleneck where different species of bacteria involved in the process either accumulate excess negative charge or excess positive charge, and cannot proceed until they neutralize that charge. Typically, they carry out the neutralization by forming “pili”, which are little “fingers” that reach out to touch other bacteria to obtain or give away these electrons. Conductive biochar, and paramagnetic biochar (which is usually associated with a high proportion of oxygen-bearing functional groups on the surface of the char) significantly improve the production of methane by giving the bacteria a chance to simply conduct their electron transfer through the char rather than by this slow process of finding other bacteria by growing pili.

See this also:
Promoting Interspecies Electron Transfer with Biochar
Scientific Reports volume4, Article number: 5019 (2014)

Note that this strictly applies to conductive biochar. Non-conductive biochar does not exhibit this effect. Conductive biochar is formed only through high-temperature processes ad we are part of this category.

Due to bioturbation (biological processes which mix the O horizon, where all the organic matter is, with the A horizon, where the mineral fraction of soil is mixed with organic matter) the biochar will be spread into deeper layers of soil. The principle organisms responsible for deep mixing are a type of worm that travels vertically between soil horizons present in many soils. (The other two types are the type that resides primarily in the organic horizon, and a type that resides in the A horizon that mostly travels horizontally.) The other type of organism that is responsible for much deep mixing is the dung beetle, which often burrows two-thirds of a meter deep. The biochar will very gradually be spread through all this soil, so it can hold a tremendous amount of biochar. You could probably add biochar compost for decades and still see it be incorporated into the subsoil.

At some point, there may be a point where there is too much biochar, but we don’t know exactly where that ceiling is. Agricultural soil keeps benefitting from soil organic matter (SOM) up to concentrations as high as 18% or more. In the soil science documentary, Symphony of the Soil, an organic farmer in the UK has soil that i