Algae technology developed by South Africa’s Nelson Mandela Metropolitan University (NMMU) that could turn millions of tonnes of coal dust wasted annually in the country and elsewhere into high quality clean coal was publically demonstrated in South Africa in late January 2014.
One of the main areas of research at NMMU’s institute of chemical technology, InnoVenton, has been the conversion of waste coal into a usable high quality clean coal using algal biomass. Researchers have found that the microalgae can be combined with coal and charcoal and acts as an excellent binder for fine coal.
“If you mix coal dust and algae biomass, the algae adsorps onto the surface of the coal and binds the dust together,” InnoVenton’s professor Ben Zeelie says. The result is a coal-algae composite, for which the name Coalgae has been coined.
The Coalgae composites may be used as a substitute in applications that require coal, or may be further processed through a variety of additional technologies, such as pyrolysis (heating in the absence of oxygen). The result of the additional processing is a bio-fossil crude oil blend that may be processed into a variety of fuels, including gasoline, diesel, kerosene, aviation fuel, and heavy fuel oil.
Carbon sequestration, the upgrading of low grade coal and the production of clean water (a spin-off of the process) are among the advantages of the production of Coalgae, which, along with the production of the bio-crude oil, have presented commercial opportunities.
Consulting engineering firm Hatch-Goba recently completed a pre-feasibility engineering study on the microalgae technologies, which has resulted in a robust and cost-effective design for Coalgae production on a semi- and full commercial scale. A full feasibility study will be conducted in early 2014.
Aspects of Coalgae technology demonstrated at the public showing included the cultivation of microalgae (in the closed photo-bioreactor system developed by NMMU), the use of coal-generated flue gas to meet the microalgae’s need for carbon dioxide and fixed nitrogen, the harvesting of the microalgae, the production of the coal-microalgae composites, and their conversion into raw bio-crude oil.