Sub-Saharan Africa (SSA) is a key testing ground for the future global bio-economy, as it lies at the heart of the “biomass-poverty belt,” i.e. the tropical and sub-tropical regions of the world where extreme poverty and energy insecurity coincide with great bioenergy potential. It is important to recognise that developing this bioenergy potential often needs to occur through both domestic AND export markets. Domestic markets by themselves are often too small to achieve economies of scale or are poorly articulated due to lack of governing legislation; export markets can attract the much-needed investment and infrastructure to support domestic markets.
Bioenergy trade with SSA is attracting considerable interest due to its mutual advantages, but the lack of infrastructure and strong institutions means that investment needs to be focused on those options with near-term commercial prospects. Bioenergy from sugarcane offers such an option, especially in southern Africa, which already has some of the world’s most competitive sugar industries. The region has significant climatic advantages for growing sugarcane, but with a few exceptions the crop has thus far been mainly optimised for sugar production. An expansion in bioenergy and biomass-based products from sugarcane will bring new economic opportunities to rural areas while supporting a more sustainable economy.
A multi-product renewable resource
The sugarcane crop has high photosynthetic efficiency and is currently the world’s most commercially important energy crop. However, the long historical emphasis on sugar (sucrose) accompanied by preferential trading arrangements have contributed to the result that only a few countries have made significant progress in optimising the crop’s overall productivity. Sugarcane offers an example of a versatile resource for food, feed, fuel, fibre and various specialized products, which together can reduce the dependence on fossil fuels in favour of low carbon development paths. Figure 1 provides an example of the energy and non-energy products that can be developed from the different biomass resource streams; as these products and processes are developed further in various world regions, sugarcane complexes are evolving into the world’s most successful and efficient models for the biorefinery of the future.
As suggested in Figure 1, the modern concept of a biorefinery has drawn considerable inspiration from the case of sugar cane as a feedstock. Such a biorefinery can provide many different energy and non-energy products and services, which are produced in tandem and with the maximum level of energy and water efficiency, recycling and ecological resource management.
Fig. 1 – Sugarcane- a muti product renewable source
Figure 2 illustrates the co-product strategies and lists the average yields for the key energy co-products. About 100 kg of sugar is recovered from each tonne of sugarcane processed, while the fibrous fraction (bagasse) can provide around 130 kWh of surplus electricity for export to the grid. Advanced technologies can increase the available electricity production to five times this level. Approximately 8 litres of bioethanol can be produced per tonne of cane in distilleries using the final molasses by-product as a feedstock. The yield of bioethanol can be increased by devoting less of the cane juice to crystalline sugar production: up to 80 litres per tonne of cane when all of the juice is used directly, as is common in Brazil. Downstream facilities can potentially provide dozens of bio-based products, ranging from fertilisers to bio-plastics. Sugarcane is among the few first-generation biofuel crops that achieve highly significant GHG savings, due to its excellent energy balance and the efficient cascading of resource use in modern sugarcane processing systems.
Fig. 2 – Development strategies and sugarcane co-products
Although Brazil, Mauritius and a few other countries have developed sugarcane as a significant renewable energy resource during the past few decades, the emphasis is still almost exclusively on sugar in many countries. Southern Africa is among the regions where the renewable energy potential of sugarcane remains largely untapped Investment in the renewable energy and biomass products’ potential of sugarcane in this region will support the global transition away from non-renewable resources and towards climate-friendly energy options. The global structure of supply and demand in these markets means that North-South and South-South cooperation is therefore needed in technology transfer, infrastructure investment, institution-building and removal of trade barriers.