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Small-Scale Biochar a Realistic Answer to Such a Big Problem?

Small-scale biochar: making it alleviates big problems and using it alleviates more.

Cool the Climate, Clean the Environment, Improve Public Health, Reduce Rural Poverty with Small-Scale Biochar – Part 5

small-scale biochar


The Case for Small-Scale Biochar

So far, I have focused on the effects of burning corn waste and what to do about it. Here I examine small-scale biochar itself to show why it is the only means available to address the problems posed by all crop waste burning. Without it, we cannot avoid the consequences of burning for the global climate, the environment, and the lives of billions of people.

How Big Is the Bigger Problem?

In 2015, developing countries produced 1.5 billion tonnes of corn stalk, 705 million tonnes of rice straw, 200 million tonnes of soy hay and 310 million tonnes of wheat straw. The big four food crops generated 2.7 billion tonnes of crop waste. Farmers may have burned 10% or 25% of this, 270 million or 674 million tonnes. Burning this much crop waste was bad for the global climate and the environment in which the global poor live. (Data FAOSTAT.)


small-scale biochar
A scene from anywhere.

Who Is Affected?

Climate change affects everyone; it is harder to estimate how many people smog and particulates from burning affect. The Food and Agriculture Organization (FAO) believes that 3 billion people live in the rural developing world, 2 billion in 475 million small farm households. If we count only the farmers who burn, we are talking 200 million (10%) or 750 million (25%) people. If we include all rural inhabitants – but not, for example, inhabitants of Delhi, Lahore or Shanxi – burning affects the lives of all three billion rural inhabitants. If we add urban areas surrounded by burning fields, we might add another 500 million. This is more than one-half the world’s population.


small-scale biochar
Crop waste fires burning across northern, central and southern China with smoke plumes running east.


Is Small-Scale Biochar a Realistic Answer to Such a Big Problem?

Not all developing world farms are small and in places even small farms permit crop waste collection. Where there are large landowners, tractors plow waste back into fields. Elsewhere state programs permit large-scale collection and processing for biochar or power.

One option is distributed biochar production. Prof. Pan Genxing at Nanjing Agricultural University, for example, has developed a system of local crop waste collection depots that serve pyrolyzers that operate year round. His system permits farmers to replant fields within days, minimizes collection, keeps capital equipment operating at capacity, provides farmers local biochar inputs and eliminates burning. On the great rice growing plains of China, Pan’s system cuts the amount and cost of synthetic fertilizer farmers require and binds up the heavy metals that contaminate many Chinese fields.


small-scale biochar
Chinese biochar-amino acid-microbe fertilizer mixer, the end point of large-scale distributed biochar production. The machine can produce 20 tonnes per year.


A second option is distributed biomass power. Locating small (1 MW) biomass power plants in areas with easily collected crop waste can provide power where needed and slash grid costs. Plants do not produce biochar, but eliminate burning and earn farmers new income. The short fuel collection radius minimizes the carbon footprint of transportation. Small size permits the use of gasifier technology that requires no local water while clean burning 17,000 tonnes of waste annually. A string of strategically placed plants could save billions of dollars and avert the environmental damage of grid construction.

So Why Care about Small-Scale Biochar?

Because neither big biochar nor biomass will go where most burning occurs.

The 475 million households farming two ha or less will never own a tractor. Their fields are too small, too steep, too rocky for anyone to want the little biomass they generate.

small-scale biochar
No one wants to harvest the corn stalk up here. Much easier to burn.


Collectively, however, small farmers produce and burn a lot of waste. (Data. FAOSTAT)

small-scale biochar

How much crop waste do they generate? Starting with conservative assumptions:

  • Real average farm size is just one ha.
  • Only one-half of all small farmers grow a big four food crop.
  • This one-half of farmers divide growing these crops equally among themselves; one-quarter grow corn, one-quarter rice, etc.
  • This gives us 475 million ha, of which one-half (237.5 million ha) is used for big four crops and this is divided into four equal portions of 59 million ha.

Even with these very stringent assumptions, small farmers are perfectly capable of accounting for more than 100% of total burning (294 million tonnes v. 270 and 737 v. 674). (See Table 1. Data, FAOSTAT)

small-scale biochar


Small farmers burn lots of biomass and will burn until offered a better alternative.

Small-scale biochar is that better alternative and it benefits everyone.

How Big Are Those Benefits?

To put eCO2 emissions from crop burning and CO2 sequestration in context (see Part 2 for the Emission Factors and data sources that generate these figures):

  • Burning 270 million tonnes of crop waste emits 289 million tonnes of eCO2. In 2015, Poland emitted 295 million tonnes.
  • Burning 674 million tonnes of crop waste emits 772 million tonnes of eCO2. In 2015, Germany emitted 778 million tonnes.
  • Biocharring 270 million tonnes of crop waste sequesters 810 million tonnes of CO2 annually. This one third as much CO2 as India, the world’s third largest emitter emitted.
  • Biocharring 674 million tonnes of crop waste sequesters 2 billion tonnes of CO2 annually. This is one third as much CO2 as emitted by the entire European Union in 2015.

The rural income impact of biochar production is also big.[1] At a field price of $0.067/kg,

  • 270 million tonnes of crop waste will produce 68 million tonnes of biochar worth $4.6 million.[2]
  • 674 million tonnes of crop waste will produce 169 million tonnes of biochar worth $11.3 million.

The Benefits of Biochar Plus

Biochar is great stuff. Making it alleviates big problems and using it alleviates more. This series, however, has made the case for small-scale biochar for a reason. Farmers worldwide can use whatever biomass they have and homemade technology to make workable biochar. But not all biochar technologies can solve the big climate, environment, health and rural poverty problems addressed here. Large-scale pyrolyzers at timber mills and furniture factories avert eCO2, smog precursor and PM2.5 emissions that would come from waste wood burning. They cannot address the huge quantity of widely dispersed, otherwise worthless crop waste in poor farmers’ fields. Only small-scale biochar made by small farmers can do this.

Making biochar from any waste biomass is good. To address crop waste burning, however, biochar must go where the problem starts: in the fields of individual, small farmers at the rural fringe of the developing world. This means small-scale biochar because there is no room for scale out where the fires – and need – are.

[1] Specific impact depends on the number of participating households. Warm Heart experience suggests that, only 1 in 25 families will make biochar. Of 2,259 households where Warm Heart first tested the model, 100 participated. These families averaged $100 each, equivalent to household income for one month.

[2] Assumes 25% conversion rate in TLUDs.


Download PDF: Cool the Climate (5 Part Series)

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  1. Arthur
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    This is very good we need to find biochar electricity generators and get them cheap so that people will use them !

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