Recycling Green Waste into Black - Biochar

Biochar offers some strong positives for use in agriculture, and not only in boosting highly durable long lasting soil organic carbon.

There are many articles on the subject, and Wikipedia has a good overview - http://en.wikipedia.org/wiki/Biochar.  I have some previous blog posts as well on soil carbon and biochar.

The article below comes from the online edition Qld Country Life and due acknowledgement is made to them.

But it is a report on a forum in which the message is being delivered to Australian farmers that biochar is not some pie in the sky airy fairy technology.......it might be real, very soon and here.

It is true that delivering adequate carbon to larger farms is a difficult and costly issue with even the logistics expensive.  But systems similar to that below will evolve, and maybe quicker than peope realise.

Using pyrolysis is a reasonably well understood process system so marrying that into a field suitable system requires application and not inconsiderable $$.  But doable.

This is a reasonable step on an evolving process.

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Revolutionary recycling

       

14 Feb 2013

 

 

TO farmers in the Burdekin it may have looked like something out of a Dr Who episode - but it is possibly the forerunner to one of the most revolutionary machines to hit the agriculture industry in decades.

A farm may never use one, but research shows that the product the unusual looking machine produces – biochar - can increase the fertility of the soil, increase moisture retention and reduce greenhouse gas emissions.

Biochar is a form of charcoal and is produced by heating organic matter in a low oxygen environment. The process is termed pyrolysis which is “a thermochemical decomposition of organic material at elevated temperatures without the participation of oxygen”. Pyrolysis can even be achieved by microwaving.

Biochar has the potential to help mitigate climate change, via carbon sequestration. It can increase soil fertility, increase agricultural productivity and provide protection against some foliar and soil-borne diseases.

The man behind the biochar producing machine at the Ayr CFI forum is Dr James Joyce. Dr Joyce did his PhD on biomass gasification and, noticing a great biomass in sugar cane trash, set out to design a pyrolysis unit that met the criteria of low capital and operating cost, mobility, flexibility and ability to handle un-shredded cane trash.

The result to date has been a series of biochar machines of various sizes. His company BIG (Black is Green) presently has two machines in Canada, one in Hawaii, Germany and Wales and two in India.  The machine not only turns potentially methane emitting, green waste into stable charcoal or biochar, the heat it produces during the process can be used to generate electricity.

One problem he has come across is finding locations with a good supply of biomass where electricity generated can be uploaded into the main grid.  The machine can convert 1.2 – 1.5t/hr of green, agricultural or industrial waste (7000-10,000t per annum) into 0.2-0.3t/hr of biochar.

Currently there is a gate price of $700/t for biochar with most outlets selling biochar at $1000-$2000 per tonne.

In Europe 80 per cent of the biochar produced is being mixed into stock feed with experiments revealing impressive weight gains and health benefits in ruminant animals.

In India biochar has become extremely popular in home gardens from which owners not only feed themselves but obtain an income from selling the produce.

Whichever way you look at it, biochar production appears destined to become a major industry throughout the world for use as a soil conditioner/ fertiliser, stockfeed additive and as a way of mitigating greenhouse gas emissions. Investors in this technology are surely on a win-win situation.    

What is biochar?
Biochar is a stable form of charcoal produced from heating natural organic materials (crop and other waste, woodchips, manure) in a high temperature, low oxygen process known as pyrolysis. Biochars can be produced from a variety of organic sources or feedstocks.

Due to its molecular structure, biochar is chemically and biologically in a more stable form than the original carbon form it comes from, making it more difficult to break down. This means that in some cases it can remain stable in soil for hundreds to thousands of years.

The production of biochar via pyrolysis also yields bioenergy in the form of synthesis gas (or ‘syngas’). Syngas consists of a variety of gases which in turn can be captured and used to produce heat and power.

Not all biochars are created equal

There are many different types and qualities of biochar. The key chemical and physical properties of a biochar are greatly affected by the type of material being used and the conditions of the pyrolysis process (i.e. temperature and time).

For example, biochar made from manure will have a higher nutrient content than biochar made from wood cuttings. However, the biochar from the wood cuttings will be more stable over a longer period of time. The two different chars will look the same but will behave quite differently.

Similarly, biochars produced at higher temperatures (700°C compared to 400°C) are more porous and more adsorptive. These biochars have greater potential to adsorb toxic substances and could be used to help rehabilitate contaminated environments

Understanding the characteristics of a particular biochar is important to match it to the requirements of its end use.