Imprimir Print

* Colombian industry only exploits the fruit of the cocoa, equivalent to just 30% of the product, discarding the rest for natural decomposition. Photo: AFP

Cocoa: From Chocolate to Fuel

May. 10 de 2012

By: Johanna Ruiz Bolaños, Unimedios

Biogas and syngas can be made using cocoa wastes, an underused product in Colombia that ends up being a significant environmental contaminant.

Cocoa is thought of and used as a fruit with gastronomic for cosmetic purposes, but the Clean Development and Energy Management Mechanisms Research Group at the Universidad Nacional de Colombia (National University of Colombia) decided to use it as a potential element for gas production.

And they were successful. Behind this "dream" was their director, Professor Fabio Sierra, who along with his team and after many months of research was able to create clean fuels derived from this fruit.

According to Sierra, when the industry works with cocoa for its traditional uses (production of chocolates or cosmetics, among others), they only exploit the fruit, which is equivalent to 30% of the product. The rest is thrown away. "After peeling the seed, the waste is left to naturally decompose", he says.

The problem is that in this process, lixiviates (liquids with organic contaminants) are produced, which leak into the soil and end up not only infecting it but also affecting the water due to their high concentrations of ammoniac nitrogen.

This waste also releases methane gas, which is naturally produced through the decomposition of organic substances in oxygen–poor environments and is much more damaging as an agent responsible for global warming than even carbon dioxide. In fact, its potential is 62 times greater than CO2 in generating that effect.

Stopping the contamination

The researchers’ main idea was to avoid such a harmful process. They therefore took the waste, dried it and placed it in ovens specially built at the mechanical workshops of the University, with the aim of warming the material to release the gas.

The procedure produced two types of fuels: syngas, obtained from carbon–rich substances, and biogas, the product of the different biodegradation reactions of the organic material, through the action of microorganisms and other factors in the absence of air.

Each has a practical function applicable to daily needs: syngas is mainly used as an intermediary in creating synthetic natural gas (SNG) and to produce ammonia or methanol.

It is also used as an intermediate product to make synthetic petroleum for use as fuel or lubricant and to convert methanol into gasoline.

It is made by subjecting a compound of carbon monoxide, hydrogen, ethane and methane to a temperature of 800ºC until it has decomposed.

Biogas is used to produce electrical energy using gas generator plants or turbines, as well as in stoves, dryers, ovens, boilers or other combustion systems.

To generate this type of inflammable substance, low–temperature ovens are used, which oscillate between 25ºC and 70ºC. The gas is made up of carbon dioxide (CO2), carbon monoxide (CO), methane (CH4) and other gases in smaller quantities, which means that it is produced with a different caloric potential.

The benefits

These substances are renewable, because they are naturally and continuously produced, as long as human beings contribute to this effect.

They are ecologically supportive because the atmospheric carbon dioxide emissions produced during the combustion process are the same ones that the plant absorbed during its growth through photosynthesis.

They are more economical in comparison with other fuels, and the creation of biomass can be increased without affecting the environment. For example, compared to the production of petroleum derivatives, there is around a 40% savings.