In 2000, Pro Natura initiated an ambitious new project: the creation of a “green” and sustainable alternative to firewood and charcoal. Two years and 5 million euros later, the result of this initiative, Biochar, won the Altran Foundation Prize for the world’s best new technology for developing nations. The process uses agricultural residues or biomass like savannah weeds, reeds, straw, stems, husk and bamboo, which would otherwise go to waste, to produce up to 5 tons per day of sustainable “green charcoal” or Biochar.
For the last decade, Pro Natura has incorporated Biochar into its climate-smart agroecology through its innovative, ecological and highly productive Super Vegetable Gardens (SVG). The result of 15 years of research, the SVG is a mode of intensive and ecological vegetable cultivation that yields up to one and a half tons of foodstuff per year on only 60 m2 of land, providing families with a nutritious diet and surplus food to sell at their local market.
The SVG production is constant throughout the year irrespective of seasons, producing a new crop of short cycle vegetables every 5 weeks. Pro Natura’s agroecological breakthroughs allow a reduction in water consumption of over 80% while reducing the labor required to about two hours per day.
The black earth discovered in Amazonia, that dates well before the Conquistadors, was nourished with ground charcoal and organic residues. Several thousand years later, this enriched soil is a lot more fertile than the normal one and the charcoal is still present, proving the stability of that type of carbon.
It is the International Biochar Initiative of Cornell University that started promoting that technology around 10 years ago and has shown that biochar stimulates the soil metabolism and immune defences of the plants that protect them against diseases and insects.
On top of that, biochar acts as a water retention agent and is particularly effective in arid soils.Today biochar is produced by pyrolysis of biomass (heating it to around 500°C in the absence of oxygen), generally crop residues. It is composed of small black fragments, light and porous.
The pyrolysis process produces a combustible gas and biochar.
Ploughing in the soil 300 gr to 1 kg of biochar per m2 increases crop productivity to levels that range from 50 to 200%. Just one application provides and maintains long-lasting soil fertility benefits that enhance carbon sequestration in the soil, thus fighting climate change.
Today, biochar research shows measurable, replicable improvements in soil productivity:
– Enhances soil biology (40% increase in mycorrhizal fungi)
– Improves nutrient retention in soils (50% increase in Cation Exchange Capacity)
– Improves the water retention capacity of soils (up to 18% increase)
– Increases the pH of acidic soils (1 point pH increase)
– Increases soil organic matter
Biochar could also be useful for breeding, by its capacity to make animals healthier and to increase the productivity, for decontaminating soils or even for filtering wastewaters.
As plants grow, they draw down atmospheric carbon dioxide (CO2) to produce biomass that contains carbon. Rather than allowing plant matter to decompose and emit CO2, pyrolysis transforms around half of the carbon stored in plant tissue into a stable and inactive form of carbon.
Biochar is also achieving the following:
– Delays oxidation of soil organic matter
– Reduces emissions of nitrous oxide (N2O) and methane (CH4)
– Increases soil organic matter sequestering carbon
– Increases plant growth
– Economises water
– Provides an option to produce renewable electricity by cogeneration
A recent study has estimated that 12% of current annual anthropogenic greenhouse gas emissions could be compensated through biochar.
Pro Natura won the Altran Foundation’s first prize for technological innovation with its pioneering pyrolysis unit. The most recent CarboChar machines are producing very high quality biochar in an ecological way from unused and renewable agricultural and forest residues.
The process is:
– Continuous: 7 days per week, 24 hours a day
– Autonomous: after ignition, the machine produces its own energy by recycling the pyrolysis gases released by the carbonisation process
– Polyvalent: all kinds of vegetal biomass can be turned into biochar. If necessary, a dryer and a crusher can be added in order to prepare the biomass for pyrolysis
– Configurable: the temperature and time that the biomass stays in the machine are optimized to make the most suitable biochar out of every type of organic waste
There are 3 models of CarboChar with daily productions ranging between 1 to 5 tonnes with yields around 40%.
The CarboChar-1 is producing 1 tonne of biochar per day and is transportable since it only weights one tonne.
The CarboChar-3 allows recovering 45% of the heat produced for co-generation. With an installation consisting of two machines of this type it is possible to produce 1.6 MW of electricity using only the co-generated heat to run a steam turbine and a generator.
In an African context, electricity can be sold at a price of 30 € the MWh and the investment gives a payback of 2 years and an internal rate of return of 29%.