THE local manufacturing and industrial sector is showing increasing interest regarding switching to biofuels as a fuel source. However, the biomass fuels market is mostly still in its infancy, making it extremely challenging for South African companies to make the right decisions when moving away from traditional fossil fuels.
“Quite often the available information on biofuels is varying and it can be difficult to get the facts – based on experience – to support a decision.
Therefore, a local energy optimisation partner’s knowledge can be invaluable,” says Dennis Williams, commercial director of Associated Energy Services (AES), a leading operations and maintenance service provider to the steam and boiler sector.
“In AES’s case, clients benefit from our hands-on experience and knowledge of fuel sources and thermal energy options. The final decision depends on individual clients’ needs and their short-, medium- and long-term objectives,” Williams explains.
‘Chipping in’ on the biofuels debate
Although the drive for a switch to biofuels is the reduction of emissions, Williams says carbon accounting can be a contentious topic, with the view that biomass is carbon neutral, resulting in the promotion of the use of biomass, even though more carbon dioxide is emitted than the same energy plant would using coal: “This is because the actual stack CO2 emission per unit of thermal energy is higher. However the CO2 emitted from biomass combustion is deemed to be absorbed by biomass that grows to replace that which has been used,” he points out.
In practical applications, it should also be considered that the chemical composition of wood includes alkaline metals such as sodium, potassium and high chloride levels.
Chemical interaction between the fuel components and the furnace refractory lining at high temperatures increases corrosion levels, elevating maintenance costs.
“Furthermore, biomass can be contaminated with sand, grit and dust. Silica-based, this interacts with the biofuel components inside a furnace, resulting in fouling and slag formation,” points out Ray Lund, operations director of AES.
Lund advises that biofuels also present ethical challenges to some companies: “When asking clients which operate on biomass why they had strict and narrow policies when sourcing fuel, we learnt that they wanted to ensure they were sourcing ‘genuine waste’ as fuel – rather than residue that was produced by cutting down trees specifically for fuel.”
One prospective client presented AES with a sliding scale of the most appropriate to least desirable choices of biofuels. Going forward, Lund believes that blue chip companies will increasingly drive ethical sourcing and require biomass to be certified as a fuel.
Even then, due to the quantum of energy required for the thermal process, larger industry has limited choices of fuels which can support the significant level of energy supply required.
“An added consideration is the ability of biomass-fuelled boilers to respond to changes in load or steam demand. “Solid biofuels, in general, respond slowly. If you have a very erratic steam profile on a pressure-sensitive process, solid biofuels are less suitable,” points out AES projects director, Gavin Evezard.
