6.6. Biofuels for Transportation
Sub-Saharan Africa has nearly 200 million hectares of cropland. Yields are generally low. Only seven million hectares are irrigated, while there is a potential for 30 million hectares of irrigation. If better farming techniques were applied, crop yields could be raised substantially. In combination with reduced wastage of harvested food crops, there is room for biomass crops. But enhanced agriculture and water management are prerequisites.
The production of, and possibilities for investment in, biofuels in Africa requires consideration of such factors as geographical location, land use patterns, preferences, income distribution patterns, as well as cultural and social aspects. Provided that work is done, there is much scope for improving agricultural productivity. Furthermore, many countries already have policies in place, or are developing them, in order to regulate biofuels production. These policies are sophisticated, but the capacity to implement and monitor them may be limited (Chavez-Diaz et al., 2010).
Improved management practices could triple yields on land currently under cultivation. This would, potentially, free up land for biofuel production. But, given rapid population growth and increasing consumption of richer food, the remaining surplus land and biomass quantities may be limited. At the same time, some countries only cultivate a small part of available arable land (for example, in Mozambique, only 10% of arable land is currently under cultivation).
A number of crops are being considered. It is estimated that the area under sugar cane in the region could be doubled without reducing food production or destroying valuable habitats. Sweet sorghum shows promise for integration with sugar cane and extending production into drier areas. Both crops can be used for ethanol production. As for oil crops, jatropha (a diesel substitute) is being planted in southern Africa with plans for expansion, but is relatively unproven and has yet to reach commercial-scale oil production. Prospects for jatropha on marginal lands in Rwanda are considered marginal (DB). Oil palm is the crop with, by far, the highest biofuel yield. Today oil palm is mostly grown in West Africa but cold-tolerant varieties have been successfully demonstrated in southern Africa (Edkins, 2010).
These are all first generation biofuel options. Second generation biofuels are produced from wood, grasses and food crop residues. This opens up a different resource potential. However, the available residue quantities are unclear and more analysis is needed. Also, the technologies are not yet mature and the second generation fuels are still considerably more expensive than first generation fuels. It is projected that second generation biofuels production could grow worldwide to around five million litres by 2015, about 5% of total biofuel production. Enzymatic hydrolysis (ethanol production) has, at present, a production cost of 0.9-1.1 USD/lge. Rapid technology improvements are occurring that may bring cost down further, such as co-fermentation of Xylose C5 sugars. Gasifica-tion for the production of biodiesel costs at present 1.4-1.9 USD/lge. Cost reductions are more challenging but important economies of scale exist.
If a ten million hectare potential is assumed for Africa as a whole, with an average yield of 5 t biofuels per hectare, the biofuel potential is around 50 bn litres, more than half of current total global biofuel production. This is equal to around 50 Mtoe or two-thirds of total African transportation fuel demand (Figure 1). However, these numbers are speculative and more work is needed to assess bioenergy potential.
UN Photo/Sebastiao Barbosa © Bundles of sugarcane from which sugar can be extracted.