Char2Cool: Turning a Rapidly Spreading Invasive Plant Into Climate-Friendly Biochar


An organisation has developed a way of turning an invasive aquatic plant - the water hyacinth - into useful biochar. The so-called C2C biochar destroys weeds, improves soil yield, protects the climate and generates new sources of income for communities.

Author Lena Strauß:

Translation Mark Newton, 11.11.20

The thoughtless introduction of a non-native species can have an astonishing, and frightening, impact on the environment. The water hyacinth is a perfect example. Introduced from the Brazilian tropics to areas of Asia and Africa in the late 19th century as an ornamental plant, it began to spread rapidly. An invasive aquatic plant, it’s regarded as the fastest growing plant in the world, as its biomass can double within two weeks. You can see the devastating extent of this spread at Lake Victoria, the largest freshwater lake in Africa. Natural predators are lacking and the growing conditions are ideal, partly due to the excessive use of fertilisers in local agriculture.

The water hyacinth can cause huge ecological, economic and social problems when it grows outside its natural home. It can destroy entire ecosystems, paralyse ships and hydroelectric power stations and put fishermen out of work. Its dense plant cover displaces the native flora by consuming nutrients and oxygen at the surface and limiting the amount that penetrates deeper. As a result of the lack of food supply, fish stocks are also reduced. The plant also impacts the water suplly in the region, as its lush foliage causes increased surface evaporation and, in addition, hinders the circulation of water. This results in ideal breeding grounds for malarial mosquitoes and increased soil erosion. But that’s not all; after dying off, the aquatic weeds sink to the bottom of the water and rot there without oxygen. This leads to the formation of methane, a greenhouse gas that is around 25 times more harmful to the climate than CO2.

Added Value Instead of Outright Extinction

The Char2Cool e.V. association, based in Reisbach, Germany is convinced that simply removing the plant will never be sustainable solution. They want to turn its removal into something constructive. That’s what led them to the idea of producing biochar. Like charcoal, biochar is carbon residue that results from decomposing biomass at high temperatures, in a process known as pyrolysis – or charring. This process is of course nothing new, but what is innovative is the use of water hyacinth as a source material. The non-profit organisation, which has officially only been in existence since February 2020, initially planned to enter biogas production, but rejected this project due to the lack of demand and infrastructure in the target countries. Olivia Thierley of Char2Cool, developed a “frugal innovation” to carbonise water hyacinth instead. The C2C-Kiln, that allows: “Anyone, anywhere, to make biochar from anything,” she tells RESET.

The materials for building the three-part C2C-Kiln, a kind of oven, cost between 20 and 80 euros and are also readily available in regions that don’t have access to a lot of resources. The operation of the kiln is intuitive, safe and requires no physical effort, explains Thierley. The individual production steps for charring are simple and can be done by hand: After the harvest, the water hyacinths are dried for about a week before being placed in the C2C kiln where it is carbonised at high temperatures (300-600 degrees) and under oxygen deficiency. Two kilns can produce 65 kg of biochar.

Natural Soil Improvement and a Permanent Carbon Sink

C2C biochar kills several birds with one stone. First of all, it can be added to soil to limit weed growth and improve soil quality. In Nigeria, for example, nutrients in soil are often leached out by state-subsidised synthetic fertilisers. Water hyacinth charcoal can compensate for this acidification, while its porous structure enables it to absorb water very well and the nutrients dissolved in it. After being added to the fields, it gradually releases these valuable substances to the plants as required. It is therefore a carrier of nutrients rather than a fertiliser itself and, in addition to other positive properties, can promote the presence of microorganisms. In Ghana, Char2Cool has been able to observe a fourfold increase in maize yields through its use.

Secondly, the charring of the water hyacinth also creates a permanent carbon sink. This happens because the CO2 absorbed during plant growth stays bound in the form of a “carbon skeleton” after carbonisation and remains stable in the soil for more than 1,000 years. Biochar is therefore a form of negative emission technologies, albeit a “low-tech” one.

And thirdly, harvesting this almost inexhaustible resource reduces the production of methane too. According to Char2Cool, one ton of water hyacinth biochar produces 200 to 300 tons of CO2 equivalents. This corresponds to the annual CO2 footprint of up to 30 people average Europeans.

A Business Model With a Difference

C2C’s biochar is made by independent producers and in a decentralised way. “Our model is to support local entrepreneurs who then manage their production independently,” says Thierley. This creates new jobs within the communities. The three-member association team passes on its know-how directly to anyone who is interested in becoming a biochar producer, by telephone, electronically or in person. “What we do isn’t driven by millions of euros, but by the motivation and entrepreneurial spirit of the local people. We do not actively seek out producers, but support those who take the initiative and contact us,” she explains.

This is how local producer Peter Bassey from Nigeria started his C2C biochar production with a start-up capital of just 50 euros. After five months, he had already produced six tons of water hyacinth biochar and hired three employees. Char2Cool has in the meantime had even more positive experiences working in Uganda, Kenya, Ethiopia and Peru. A future challenge will be to create a local market for the biochar. Many farmers are simply unfamiliar with the product and its benefits, namely faster plant growth and higher yields with less water and nutrient consumption. For this reason, they are setting up a training centre and demonstration area in Nigeria where they’ll offer workshops on the subject of biochar and its benefits.

And because biochar helps fight climate change, it will in the future also be possible to buy carbon offsets directly through Char2Cool – without any middlemen and with calculations based on verified CO2 savings per tonne of water hyacinth biochar. So far, Char2Cool’s CO2 carbon offsets are only being sold within its own network and to individual companies, but they’re organising a crowdfunding campaign right now to fund the project’s development and to reach new markets.

Digital 3D Soil Maps Help Make Farming More Environmentally Friendly

A young company from Berlin wants to use 3D soil maps to make agriculture lower in emissions and more resource-efficient. Satellite and aerial photographs provide the data. Co-founder Suvrajit Saha explains to RESET in an interview how the soil maps are produced and who is benefitting from this new knowledge.

How Social Networks Are Helping Indian Farmers Hit By the Coronavirus Lockdowns

When strict coronavirus restrictions were introduced throughout the country, Indian farmers' crops began rotting in the fields. But thanks to the innovative use of social media, they're connecting directly with their end consumers - and finding a way out of the crisis.

An AI-Powered Plant Doctor Helps Farmers Tackle Crop Pests and Plant Diseases

The Plantix app uses machine learning to detect crop pests and diseases and provides tips on how to treat them - helping ensure greater food security and secure the livelihoods of small farmers.

The Dutch Community Farm Looking to Tackle Climate Change By Reconnecting People with Food

In an attempt to promote sustainable, local agriculture, Dutch families are banding together to create new community farms based on age-old farming ideals.

© Meike Engels
RESET’s Keynote on Vertical Farming

At the end of 2018 RESET writer Indra Jungblut gave a keynote all about Vertical Farming. Here's a look back at the event.