Shamim Mia
Biochar and its concept:
Biochar is a term synonymously used for charcoal, char and agri-char. As described by International Biochar Initiatives (IBI), it is charcoal made from pyrolysis of biomass and purposefully applied to soil for soil fertility improvement and attaining environmental gain. Basically, biochar is pyrolysed biomass. Pyrolysis is the thermal decomposition of biomass i.e. biomass is conversed to char, syngas (mixture of H2, CO, CH4 and CO2) and bio-oil with heat energy in absence of O2. When biomass is subjected to heating under limited or absence of O2 it undergoes physical and chemical changes. The carbon chains in biomass are fused together and condensed to form aromatic moieties (as in graphite) which are connected via aliphatic chains and about (50%) of biomass carbon retains in the char. In contrast, during burning the biomass carbon is converted to CO2 in presence of O2 and 97% carbon is lost.
Biochar effects on climate change mitigation
When the climate change issue propped up, scientists devoted themselves to find out how to combat with incremental concentration of CO2 in the atmosphere. In close look to the carbon cycle, they found two-third of the carbon of the carbon cycle is in the soil. Then, the scientists tried to answer whether they could put more carbon in soil as it is the largest reservoir or whether they can increase the residence time of carbon in soil. In a study with Amazonian Terra Preta soil popularly known as Terra Preta de Indio, it has been found that there are some carbon which has been in the soil for >1000 years. This carbon was added as char by indigenous Brazilians. Professor Johannes Lehmann, Cornell University, USA took the lead of research about carbon sequestration in soil through biochar amendment. He published an article in the famous scientific journal “Nature” where he mentioned that carbon sequestration in plant is carbon neutral i.e. the amount carbon taken by the plant is as much it releases to atmosphere. However, if biomass is converted to biochar it is carbon negative. As it has been shown in the figure of Lehmann’s article, plant provides 50% of its biomass to the soil and this 50% biomass goes back to atmosphere by decomposition process. If 50% of the plant’s biomass is pyrolysed, 25% remained in the char. In many scientific studies it has been proved that the char is resistant to microbial decomposition and thus it stays in soil for 100- 1000 years depending on its quality. So, if we convert biomass to biochar and apply to soil, the carbon will remain in the soil for thousands of years. Thus the atmospheric carbon can be sequestered in the soil as biochar or char. It has been estimated that the world could be carbon negative using only 10% of its productive degraded land, which is capable of absorbing an estimated 6.1 Gt of CO2, if carbon is applied as biochar. After biochar amendment, reduced greenhouse gas such nitrous oxide and methane emission from soil has also been reported in a number of scientific studies. Therefore, biochar application to soil is a potential tool for climate change mitigation.
Biochar and bioenergy generation
Biochar is, in fact, bioenergy by-product. When biomass is pyrolysed, the biomass produces syngas (mixture of H2, CO and CO2) and huge amount of heat which can be utilized as power for cooking (for small scale plant) and electricity generation (large scale plant). If pyrolysis is conducted at high temperature (>700°C), bio-oil can be collected. Industrial bioenergy generation with simultaneous biochar production is growing quickly in the developed world for instance Pacific pyrolysis in Australia, IEA Bioenergy in Germany, Biomass Technology Group in the Netherlands, Bicarbo in Brazil etc.
Biochar effects on agricultural productivity
As it has been described above, the concept of biochar has been developed from ancient historical charcoal added Amazonian soil know as Terra Preta soils. This soil is called the black gold of Amazonian area as it is highly fertile and still sustaining high productivity. Considering the benefits of Terra Preta Soil, scientists devoted themselves to incorporate similar type of char (named as biochar) into soil and to harvest similar benefits. Indeed, they have succeed and abled to prove that artificial biochar can increase soil fertility and crop yield. A PhD student of Professor Johannes Lehmann, a leading scientist of biochar research mentioned in a YouTube video that an unimaginable increase of 880% in crop yield is obtained when biochar is co-applied with mineral fertilizer. In fact, an 880% increase in crop yield is fancy. Nevertheless, Dr. Simon Jeffery, researcher at the Wageningen University, the Netherlands found positive crop yield in a meta-analysis of many scientific articles. So, it would be interesting for us to produce and apply biochar in our soil to harvest the benefits.
Biochar effects on environmental reclamation
In a number of study, it has been shown that biochar has the potentials to trap both organic and inorganic pollutants including pesticides from environment. Like activated carbon, it can be used for water treatment. Moreover, if biochar is produced from waste biomass, environmental pollution can be reduced considerably. As compared to biomass burning, the release of smoke and gases is low in pyrolysis process. So, it could be a good technology for us, if we could utilize our municipal waste for biochar production.
Biochar Research in Bangladesh
Biochar research has opened a new avenue for scientists of the leading university of world. Those university which are rigorously looking into biochar technology includes University of Western Australia, in Australia; Wageningen University, the Netherlands; University of Bayreuth, Germany; China Agricultural University, China; University of Toronto, Canada and Cornell University, in the USA. United Kingdom has forwarded one step further by establishing UK Biochar Research Centre at the University of Edinburgh. As a result, a huge number of articles (>1000) has been published in scientific journal on biochar technology in the last 10 years. National and international research groups have also been formed. Unlike most of the leading universities and research organizations in the world, the biochar research in Bangladesh is quite new and poorly developed. I hardly find any articles from Bangladesh in scientific journals. The main constraint of biochar research in Bangladesh is the biochar production technology, although it is not too advanced technology. However, from my knowledge, I know few Bangladeshi who are working on biochar technology in the developed world. Recently, Christian Commission for Development in Bangladesh has started to work on biochar production and extension from January 2014. They have opened a blog, Bangladesh Biochar Initiatives. While pursuing MSc in Wageningen University, the Netherlands, I got idea about biochar production. After coming back to Bangladesh, we in a group devoted ourselves to make a biochar production kiln with the help of small funding from Patuakhali Science and Technology University (PSTU). We in needed have succeed and developed two biochar kiln; one for farmers’ use and another for semi industrial use. Two MS students of Department of Agronomy have completed their MS theses using our biochar. We have also tested our design in Chittagong Hill as a pit kiln. Of course we have to fine tune our technology before large scale use.
Prospect of Biochar Technology in Bangladesh
As a technology, biochar could be a very promising technology for Bangladesh. First, we have huge amount biomass waste, for instance, Dhaka city alone produces more than 3000 tons of waste per day. We also have poultry litter and huge amount of solid waste like apparel industry by-products. Furthermore, we also have wood biomass which we use for cocking purposes. These biomass can be used for dual purposes both for power generation (cooking and electricity) and biochar production. Second, the percentage of organic matter, the life of soil, is alarmingly low and decreasing for our intensive crop production practices. Application of biochar can solve this problem as it retains in soil for many years and can serve soil functions. Third, biochar increases fertilizer use efficiency especially the N by reducing leaching. So, fertilizer costs for urea might be reduced considerably if we can adopt biochar technology. In addition, it has been shown that P bioavailability increases with biochar amendment in highly weathered soils. So, it could be a very good soil amender for our red soils (ferrosol). Nevertheless, biochar can also be used as organic and inorganic pollutant absorber. Therefore, we might use biochar to treat industrial effluent which otherwise pollute our rivers. This is very simple and easy technology which can be used by anybody and in anywhere. So, shouldn’t not we explore this technology?
Author is a University Teacher and Researcher; Email:This email address is being protected from spambots. You need JavaScript enabled to view it.
