Publisher: Langmead &
Baker Ltd. Managing Editor: Margaret Thompson.
By Prof F.D.Yamba, Centre for Energy, Environment and Engineering, Lusaka
Recent events related to global uncertainties in fossil fuel supplies and high world oil prices, on the one hand, and the need to reduce poverty, particularly in Africa, on the other hand, have intensified the motivations to shift to biofuels use.
There is now a growing frenzy of interest, especially among both small-scale and large farmers in Africa, to grow energy crops from different sources.
This interest is being induced by the realisation that biofuels can be used for heating, power generation and transport purposes. Because of this motivation and interest, an excellent opportunity now exists to propel biofuel production for sustainable development.
Despite this potential, there exists local, regional and global challenges which need to be considered.
In some cases, the challenges can be taken advantage of to enable agricultural biomass, a huge resource in Africa, to be converted into a variety of biofuels such as ethanol and biodiesel.
Ethanol can be made directly from sugar-bearing crops, and indirectly by converting the cellulosic portion of biomass into sugar . Biodiesel can also be produced from vegetable oil seeds through use of extraction technologies, and a chemical process known as esterification .
Challenges and Opportunities
From a global perspective, growing concern about the sustainability of energy supplies (especially in the transport sector), supply security and the need to take action on climate have all served to increase interest in biofuels . As regards security of supply, both biodiesel and ethanol can play an important role to increase use of domestic resources in the transport sector, and at the same time address local, regional and global environmental concerns.
The key driving forces for biofuels in the European Union (EU) are the Directive for Promotion of Biofuels and Directive of Fuel Quality [3, 4]. The former, which requires member states to set indicative targets for biofuels sales in 2005 (2 per cent) and 2010 (5.7 per cent) is motivated by the need to cut greenhouse gases and increase energy security by reducing dependence on imported fuels . As a result of this directive, it is estimated that a market demand of 10.5 billion litres of biofuels with be created .
As regards meeting the Directive on Fuels Quality, biodiesel has useful properties as it is known to release fewer solid particles than conventional diesel, and contain no sulphur and release no SO2, which contributes to acid rain. Biodiesel also has rapid biodegradability qualities, low toxicity to people and the environment, and a high flashpoint. Ethanol, on the other hand, is CO2 neutral because the carbon diode released during combustion is absorbed from the atmosphere by the next generation of crops. It can also compete with methyl-tertio-butyl-ether (MTBE) as an octane enhancer in addition to having less impact on the environment (both air and ground), and being less harmful to health.
Due to limited land availability, and relatively high cost of the feedstock rape seed, it is unlikely the anticipated demand of 10.5 billion litres of biofuels in the EU will be met by domestic supply. This market is of significance to creating a biofuels industry in Africa.
National Regional Perspectives
Apart from high world petroleum prices, two other factors beginning to have an impact on biofuels development in Southern Africa are the EU Preferential Trade Agreement Sugar Reform, and the Africa Dakar Declaration on replacement of lead as an octane enhancer for gasoline fuels. The Dakar Declaration, which came into effect at the end of 2005, requires substitution of lead as an octane enhancer.
Some refineries in the region as a short term measure have resorted to use of MMT a manganese based additive. But MMT also raises different concerns over potential health risks, and is thus viewed as controversial . Another approach is for refineries to manufacture high-octane gasoline through use of catalytic reforming units. For many refineries in Africa, this will require upgrades, and large capital outlays, which will not be affordable . In the medium-term, most countries in the region are seriously considering use of ethanol as a substitute for both lead and MMT.
The recent announcement under the EU Sugar Reform to reduce the EUs intervention price by 36.0 per cent will have an impact on the competitiveness of sugar industries within the African, Carribean and Pacific regions (ACP). For them to survive this will require innovative diversification plans into other core products such as ethanol and co-generation.
Production Technologies/ Processes and Economics
Various technology configurations are available on the market for ethanol production. Their concepts are largely influenced by the feedstocks used and composition, whether anhydrous or hydrous. The former is suitable for production of fuel as a transport fuel. The type of technology used can either be annexed or autonomous. For Southern Africa, annexed distillation has the greatest potential, in view of the structure of the sugar industry.
Ethanol can be obtained from many different feedstocks, in fact from any sugar-containing raw material. Feedstocks can be classified into three main groups:
(i) Sugars: (i.e. sugarcane, molasses, fruits, etc) that can be converted to ethanol through fermentation and distillation
(ii) Starches: (i.e. grains like maize, root crops like cassava), which must be first be hydrolysed to fermentable sugars
(iii) Cellulose (i.e. woody material, agricultural waste, black liquor from pulp and paper which must be converted to sugars by action of mineral acids
From an economic point of view, very few materials can seriously be considered as feedsock. And from Southern Africas perspective, sugarcane and sweet sorghum offer promising feedstocks (examples: Brazil, Malawi, India, Kenya and Zimbabwe) . Quantities of ethanol and feedstock required depend on the demand, which in turn is influenced by the level of blending (5 per cent, 10 per cent, 15 per cent). At present, most of the ethanol is produced from cane molasses, which, however, has limited availability, being a by-product of sugar factories and has limitations on waste water control.
In view of such limitations, there is a need to exploit new agro-based feedstocks. For such feedstocks to be attractive, they need to have the following characteristics: sugar-bearing, remunerative for the farmers, low cultivation costs, viable for alcohol production and giving zero discharge of waste water.
Taking into account the climate and soils in southern Africa, one such feedstock that can be effectively exploited is sweet sorghum. It has the following characteristics:
Short cycle crop 3.5 months
Can be grown across warm climate regions
Easier to grow and handle (vis-à-vis sugar cane)
Low cultivation costs
Known to farmers robust crop- practices similar to sugarcane
Gives fodder for cattle
Gives bagasse similar to sugarcane energy for distilleries
The production of biodiesel is well known. Three basic routes to diesel production from oils and fats exist, and are listed below:
Base catalysed transesterification of the oil with alcohol;
Direct acid catalysed esterification of the oil with methanol;
Conversion of the oil to fatty acids, and then to alkyl esters with acid catalysts.
The most commonly used and most economical process is called the base catalysed esterification of fat/oil with methanol, typically referred to as the methyl ester process, due to the following :
Low temperature (65.6oC) and pressure (20psi) processing;
High conversion (98%) with minimal side reactions and reaction time;
Direct conversion to methyl ester with no intermediate steps;
Exotic materials for construction are not necessary.
The amount of feedstock requirement in the region to produce biodiesel depends on the amount of diesel consumed and the percentage of blending. Traditionally, conventional major feedstocks for the methyl ester process are cotton seed oil, soybean and peanut oil.
Another suitable feedstock for the methyl ester process, which can be used and grown in southern Africa, is Jatropha, attractive in view of uncertainty of conventional feedstocks and also to avoid conflict between energy and food, since it is a non-edible oil.
The characteristics of Jatropha that make it superior to conventional feedstock are listed below :
Jatropha curcas L. belongs to the family euphorbiaceae;
Growing period = approx. 100 days;
Grows on well drained soils with good aeration, and is well adapted to marginal soils with low nutrient content;
Yield ranging between 5 to 10 tonnes per hectare;
Oil content = 40 per cent;
Grows as a shrub, and needs no fertilizer.
Given in table 1 is a comparison of local ethanol prices and other international prices.
Prices obtained from local production compare favourably with Brazil, and are more competitive than the USA. depending on the feedstock.
Table 1: Comparison of Local Ethanol Prices and Other International Producers
Country Ethanol Price (Gasoline Equivalent)
US cents Feedstock
Southern Africa 20-25 Molasses
Sweet sorghum juice
Brazil 25-30 Molasses
USA 40-50 Corn
EU 50-90 Cellulose
As in the case of ethanol, biodiesel prices are equally comparative with other producers in Europe as shown in table 2.
Table 2: Comparison of Biodiesel Prices
Country Biodiesel Price (diesel equivalent), US cents Feedstock
Southern Africa 30-35 Jatropha
EU 40-80 Rape seed
EU 25 Waste oil
Southern Africa has great potential to greatly benefit from the use of its natural resource endowment base to produce biofuels, and if such projects are implemented they will go a long way to achieving a sustainable energy path, and contribute significantly to poverty reduction through creation of numerous jobs from agriculture, processing and marketing.
1. Deborah W. Cornland, Francis Yamba, Francis X. Johnson, Et al (2001): Sugar Resources for Sustainable Development: A Case Study in Luena, Zambia, Stockholm Environment Institute, Sweden, ISBN-91-88714-71-3.
2. National Biodiesel Board (2003): www.biodiesel.org.
3. Larsen, H. Kossman J., and Petersen, L. S: New and Emerging Bioenergy Technologies, Risoe Energy Report 2, Riso R-1430 (EN). ISBN 87-550-3261-5.
4. Wood, P.: Out of Africa, Could Jatropha Vegetable Oil be Europess Biodiesel Feedstock? Reforms July/August 2005. 1471 0 846105 2005. Eisevier Ltd, 2005.
5. Yamba, F. D. and Matsika, E. (2004): Factors and Barriers Influencing the Transfer and Diffusion of Biofuels Producing Based Technologies With Particular Reference to Southern Africa, presented at the Industrial Technology Development, Transfer and Diffusion IPCC Expert Meeting, Tokyo, Japan, 21-23 September 2004.
6. Yamba, F. D. (2003): CARENSA Working Paper : Benefits From Sugarcane Co-Products And Policy Issues, Durban.
7. Shumakar, G. A, McKissick, J., Doherty, B. (2002): A Study on the Feasibility of Biodiesel Production in Georgia.
8. AREED (2003): Feasibility Study on the Production of Biodiesel in Chavuma, Western Province, Zambia.
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