Food waste, yard trimmings, manure, and even human sewage can be turned into solid biochar to generate energy . If scaled up, they could help adjust industrial carbon demand and the need to get rid of organic waste as well as reduce greenhouse gas emissions.
Europe has a bio-waste problem . Instead of using carbon-rich material as fuel, millions of tons of organic waste are dumped in landfills, where they decompose and emit greenhouse gases.
At the same time, the European Union imports millions of tons of coal for industrial use and power generation . It is a raw material that is subject to vulnerable supply chains and that adds to the carbon emissions, on which Europe intends to reduce its dependence.
Efforts to compensate for these imbalances could find a solution in biochar, a carbon neutral commodity made from organic waste , which can be used as an energy source, as an industrial raw material or even as a form of storing carbon, rather than emitting it into the atmosphere.
“Biochar technology can play an important role in the market. Firstly because we recover a high-value material, secondly because it is fast, and thirdly because it can avoid CO2 emissions, “said Marisa Hernández Latorre, founder and CEO of the sustainable technology company Ingelia, based in Valencia, Spain.
To make this carbon substitute, a process known as hydrothermal carbonization (HTC) can be used, which uses superheated water under pressure to produce biochar in a few hours. In nature the geological formation of fossil coal takes millions of years.
“It is really a very simple and stable process because it acts as an acceleration of the natural formation of coal,” said Hernández Latorre.
Ingelia has developed its own HTC process for three biochar plants in Spain, the United Kingdom and Belgium, with a total capacity of 8,000 tonnes of biochar per year. Several more are awaiting regulatory approval and should double their capacity in the coming years.
“HTC’s biochar not only avoids the use of coal in industrial processes, but also the emission of methane from landfills,” said Hernández Latorre, adding that the technology can recover up to 95% of the carbon from organic waste.
Methane is a greenhouse gas even more powerful than carbon dioxide, and a notable source of it is landfills. Europe dumps millions of tonnes of biological waste into landfills every year, and even where there are methane capture systems, a substantial part of the gas can escape.
Pressure cooker
Several different HTC methods have been developed, but the process generally works according to the line of a pressure cooker, although the ingredients range from residues from food or beverage processing, agricultural waste, forestry industry discards such as chips and sawdust. , to corncobs and sewage.
The biological waste is introduced into a device known as a reactor, at temperatures of 180 ° C-250 ° C under a pressure of the order of 2 megapascals (MPa) or 20 atmospheres. This means that the water in the system is overheating, rather than turning into steam.
The reactor converts the solids from the organic matter into hard biochar (also known as hydrocarbon), while the liquids can be collected separately and used as bio-fertilizer. The gases that are released are captured and used to power the system.
Biochar has similar characteristics, regardless of the biological waste used, although the different raw materials influence the quality by determining the ash content. Conditions in the reactor destroy pathogens and the resulting products are sterile. Carbon slurry can also be processed to remove stones or glass or metal shards, before being compressed into briquettes or pellets.
Ingelia’s HTC core process can use food waste, for example, to produce biochar similar to fossil brown coal, which comprises around 60% carbon. This hydrocarbon can then go through additional steps to make higher value “designer” biochar, removing ash and volatiles to ensure a carbon content of up to 90%, capable of competing with premium quality coal.
“We can use post-processing to tailor the final product, to recover from the biomaterial exactly what is needed for industrial processes in a circular economy,” said Hernández Latorre.
Greenhouse gases
Hernández Latorre says that Ingelia’s internal research shows that per tonne of HTC biochar produced, between 6.5 and 8.3 tonnes of CO2 are avoided , compared to a landfill operation with or without a methane recovery system.
Hernández Latorre believes that biochar can have a market value of 170 euros per tonne for the most basic hydrocarbon and more than 400 euros per tonne for premium-quality biochar with the highest carbon content, depending on the use that is going to be made of it. give.
Ingelia has combined the results of several research projects in its HTC process and is targeting its technology at coal-dependent industries, wastewater processing, which has to deal with organic waste, and energy producers that are going through from power generation from coal to renewable energy.
With coal prices falling and demand in the economic slowdown caused by the COVID-19 pandemic , it may take time for biochar to displace fossil fuels in industry around the world. However, it offers a solution for those who are obliged to treat organic waste and to comply with the European Union’s plan to be carbon neutral by 2050.
Hernández Latorre, who on June 12 was named Champion of the EU Innovation Mission for her work in research on clean energy, believes that it will play an increasingly important role in the next 10 to 15 years.
“The market is really ready to accept or implement new technologies, all it needs is that they are sufficiently developed at scale,” he added.
Industries need sufficient availability of biochar on the market to plan ahead for the replacement of fossil fuels. And investors want to be sure they will have enough biowaste to process (and a commitment from users to use their products) before investing in sophisticated HTC units that could cost hundreds of thousands or even millions of euros.
Unsophisticated technology
These set-up costs are prohibitive in many developing countries, although biowaste is a problem worldwide.
However, a low-cost, low-tech version that uses human feces to make biochar and fertilizer could bring double benefits to places where people lack sanitation facilities, said South Korean researcher Dr. Jae Wook Chung.
Chung sees potential both to generate income for communities and to address their environmental and health problems caused by untreated excrement, citing WHO estimates that 673 million people have to defecate in the open (on the street, behind shrubs or in open water).
Research has shown that HTC reactors can be made for less than € 20,000, but Dr. Chung plans to use a project called FEET to develop an even simpler and cheaper model that can be used in poor, high-density communities. like the Kibera slum in Nairobi, the capital of Kenya.
It envisions a system the size of an oil barrel, made of stainless steel tubes, available as a construction supply in many developing countries. And he wants to monitor temperature and pressure from outside the reactor, avoiding expensive probes.
Dr. Chung will also focus on ways to ensure a sustainable supply of waste for processing (perhaps through organized emptying of pit latrines or portable sinks) and demonstrate the economic benefits of biochar and liquid fertilizer.
He believes that making a sanitation system profitable for the community is the key to making it sustainable, and to providing toilets in regions that currently lack them.
“The financial benefit would also help those who have a cultural barrier to using conventional toilets to stay away from open defecation,” he said.
Artículo original
This article was originally published in Horizon, the EU Research and Innovation Magazine
