Although the South African sugar industry is still considered one of the world's low cost producers, it is a mature industry, showing signs of decline and it is facing a changing and increasingly competitive marketplace. In order to reverse this in the medium to long term and enhance the sustainability of the industry, the challenge is to maximise the value potential of the entire crop and generate additional revenue through product diversification that would be distributed throughout the value chain, right back to the growers and the rural communities that they support (Figure 1).
Figure 1: the sugarcane to sugar value chain
The challenges facing the South African sugar industry are not unique. Both the South African and the international sugarcane industries have been moving towards the integrated biorefinery approach (see Figure 2), in which sugarcane is viewed as a source of biomass that can be processed to produce a diverse range of value-added chemical and energy products, that may range from crystal sugar to biomaterials to fuels such as ethanol or important feed-stocks for the production of chemical and other materials, within an integrated approach which optimises the overall profitability of the industry.
Figure 2: the Integrated Biorefinery concept
For example, a component analysis of sugarcane indicates that value is currently extracted from essentially only a small proportion of the sugarcane stalk: sucrose represents only approximately 15% of the stalk mass, whilst fibre represents a similar value and a further approximately similar amount of potentially valuable fibre is currently left or burnt in the field. The maximum value potential of the fibre in the cane can be realised by considering it as a raw material for beneficiation by either chemical, thermochemical or biochemical modification to produce “building block chemicals” which can be subsequently converted to high-value, bio-based, chemicals or materials. This would stimulate a reinvestment into sugarcane growing which would have a knock-on effect of increasing the availability of the biomass for processing and value creation. However, such technologies and platforms will require considerable further long-term investment into research, development and innovation (RD&I), while the industry needs short and medium term solutions to remain sustainable until such advanced solutions are discovered and commercialised. A public:private partnership programme (STEP-Bio), funded by the SA sugarcane milling industry and the national Department of Science and Innovation's Sector Innovation Fund programme from 2014 to 2019, focused on the short-to-medium term RD&I interventions that will allow the industry to maximise returns in the near future, although further investment into the development of higher value products from the beneficiation of sugarcane and its products will be required. As part of its biorefinery approach to its research strategy, the SMRI identified a number of key focus areas where Research & Development is required, in three core technology areas: fractionation/preparation, separation and conversion (Figure 3). Some of the specific technologies that have potential are shown, such as ionic liquids, enzymatic fractionation and conversion, membrane technology, gasification and Fischer Tropsch catalysis. In addition, there is a need to consider technologies to convert the factories from being energy sufficient to being energy efficient, so that the full value of the potential energy in the biomass may be realised. Furthermore, the integration of processes, products and technologies must be considered with an over-arching Biorefinery Techno-economic model in order to identify the best options for deriving maximum value from the sugarcane. For further details on the STEP-Bio Programme, click here.
Figure 3: elements of an integrated sugarcane biorefinery
