Ethanol as a transport fuel has several merits. First, it acts as an oxygenate in petrol, thus reducing emission of carbon monoxide by taking combustion to completion. Its use does not require major changes in the existing petrol engines. In addition, ethanol production provides a boost to the rural economy and creates rural employment. For India, which is heavily dependent on imported oil, development of locally produced biofuels should be a priority. However, much more needs to be done for ensuring sustainable supply of ethanol and to realise its full potential as a transport fuel.
India has been experimenting with ethanol for several years. In January 2003, 5% ethanol blending in petrol was made mandatory in nine states. But the plan ran into trouble in 2004 due to a poor harvest of sugarcane and subsequent shortage in ethanol supply. In October 2004, the government made ethanol-doping conditional, highlighting the need for an assured supply of ethanol.
Unlike Brazil, in India sugarcane juice is not directly used for ethanol production. Ethanol is made from molasses here, a by-product of sugar production. It is estimated that utilisation of all the molasses produced here can yield 2 million kilolitres of alcohol every year, of which about 0.8 million kilolitres of ethanol can be spared for blending in petrol. If all the 0.8 million kilolitres of ethanol is made available, it can replace around 9% of the current petrol requirements.
For sustainable supply, production needs to be enhanced. One option could be to divert a part of primary or secondary sugarcane juice from sugar production to ethanol production. The other option would be to increase the area under sugarcane cultivation. However, India has limited potential to go for the latter due to constraints in irrigation and the competing requirement of irrigated land for growing other food crops. So emphasis should be on increasing sugarcane yield, at present stagnating at 60-70 tonnes per hectare.
Among alternate feedstocks, sweet sorghum is a potential option; compared to sugarcane, it is a less resource-intensive crop and is drought-tolerant. Several countries like China are developing their ethanol programme around sweet sorghum.
A distillery plant of 40-kilolitre-per-day capacity was recently commissioned in Andhra Pradesh. According to Icrisat (International Crops Research Institute for the Semi-Arid Tropics) scientists associated with this project, the production cost of ethanol from sweet sorghum has proven to be lower compared to sugarcane-based production. Thus, a comprehensive assessment of the potential of sweet sorghum for ethanol production is needed.
In the longer term, ligno-cellulosic raw materials (such as agro-residues, perennial grasses, etc.) offer great promise. Total agro-residue production in India in 2001 was estimated to be 800 million tonnes. Utilisation of 6% of this can theoretically produce around 9.0 million kilolitres of ethanol, which can meet 100% of the current petrol requirements. India also has a large number of grass species, which can potentially be used as raw material for ethanol production.
The governments plan to make blending of 5% ethanol with petrol mandatory from October 2006 is a welcome step. But for a steady supply, we need a long-term, comprehensive policy on biofuels with clear targets, a well-defined pricing policy and a road-map to develop a variety of feedstock options for biofuel production.
The writer is director, energyenvironment technology division, Teri