Biochar Origins, Generation from Organic Waste, Applications and Benefits: A Review

Odette Varela Milla ； Wu-Jang Huang

《國際創新發明大會》 2010 (2010/10) Pp. 53-54

並列摘要

All living matter contains carbon; you and me are a carbon-based life forms. When plants photosynthesize they absorb carbon dioxide and emit oxygen. It is how oxygen comes to be on the planet in sufficient quantities for us to breathe. If the biomass from plants is heated in a closed container with no or restricted oxygen, in a process known as pyrolysis, it creates charcoal, or biochar. This is simple and ancient technology and is historically not a new practice. It has re-emerged after the study of the Terra Preta do Indio, which are highly fertile soils. These soils were created by Amerindian populations in pre-Columbian times. Plants have known how to absorb carbon dioxide for roughly 3,000 million years; mankind has known how to make biochar since prehistoric times. But modern technologies do play a part; old style charcoal-making tended to be rather a dirty business. The modern twist is that the gases that the carbonizing wood gives off can be fed back into the burner to fuel the heating process. This means that instead of methane emissions all that is given off is a little carbon dioxide and steam, far less than if the biomass were burnt or allowed to decompose. One tonne of dry biomass will create 400 kilos of biochar which will be 80% to 90% carbon. So roughly for every tonne of biomass, you get about a third of a tonne of carbon. That carbon capture is tangible, you can see it; you can touch it; you can weigh it.
Biochar provides a singular mechanism to absorb carbon dioxide from the atmosphere and store it back in the soil. Biochar can aid in: nutrient retention and cation exchange capacity, decreasing soil acidity, decreased uptake of soil toxins, improving soil structure, nutrient use efficiency, water-holding capacity, and decreased release of non-CO2 greenhouse gases. Many forestry and agricultural residues can be used to produce bio-char and applied to agricultural soil both to sequester C and to improve the production potential of crops. In many cases, these spent materials have little value and their disposal incurs costs. Organic wastes originate from plant or animal sources, food scraps, garden waste, sewage, paper and wood. Organic waste can be recycled. Compost, biochar, soil conditioners and biogas are some of the products that can be produced from recovered organic waste. When organic waste decomposes in landfills it produces a gas known as landfill gas, which consists of about 55 per cent methane. Methane gas has a global warming potential 25 times that of carbon dioxide, is odorous and highly flammable. There is great potential for biochar production and application to have positive outcomes through carbon sequestration, and improved soil health.

並列關鍵字

agricultural waste ； biochar ； biomass ； CO2 ； carbon sequestration ； organic waste ； Terra Preta do Indio