Biofuels get green signal

The biofuels industry has the potential to make significant contributions to meet the world’s energy needs and help reduce the dependence on fossil fuels. However, there are many challenges that face the implementation and acceptance of biofuels.

To promote this emerging renewable energy option and to address the larger environmental and social impacts of adopting biofuels technology, Winrock International India (WII) organised the sixth International Biofuels Conference in New Delhi from March 4-5. The two-day conference saw experts, academicians and scientists debate policy perspectives on biofuels, their use in the transport sector, the food versus fuel debate and next-generation biofuels.

According to WII, India is making efforts to supplement petro-based fuels by indigenously produced renewable feedstock. The country's current biodiesel technology of choice is the trans-esterification of vegetable oils. Based on the findings from extensive research, the Indian government plans to use non-edible oil from jatropha curcas and other tree-borne oil seeds as feedstock for biodiesel. The ambitious National Biodiesel Mission plans to meet 20 percent of the country’s diesel requirements by 2011-2012.

The experts however noted that the Indian biodiesel market trails its global counterparts by a long way. Lack of large scale availability of feedstock is the greatest challenge that the industry is grappling with. They believe that possibly after four years and many plantations later, the country many have the feedstock necessary for large-scale production of jatropha oil for use in biodiesel. Also, the absence of a clear government policy on jatropha oil production has inhibited biofuel manufacturers from entering the market.

The ethanol industry, though mature, can benefit from improved agricultural practices in sugarcane cultivation, more efficient production processes and the use of alternate feedstock including cellulose material. While the biodiesel industry is at the incubation stage, large scale jatropha cultivation and the infrastructure for oilseed collection and oil extraction must be established before the industry can be placed on a rapid growth track, they argued.

Jatropha oil as a popular fuel feedstock

Dr George Francis of Live Energies GmbH, Germany, in his presentation maintained that the oil produced from jatropha seeds is an ideal feedstock for high quality biodiesel production. The hardy jatropha is resistant to drought and pests, and produces seeds containing up to 40 percent oil.

When the seeds are crushed and processed, the resulting oil can be used in a standard diesel engine. Jatropha biodiesel is comparable in most fuel properties to petro-diesel and causes lower particulate emissions when used as fuel in automobiles. Its advantage over other crops could become more obvious only if potential for viable production of oil from wasteland is fully realised, he noted.

“The long term experience with jatropha in the past has been in its establishment as a survivor plant. Its seeds were harvested, if at all, in a very low intensity manner and there is little experience with the post- harvest handling of all the seeds. The present interest in jatropha is based on the assumption that it can grow and produce seeds at a commercially viable level on land that is not suitable for commercial agriculture,” he said.

He, however, said that there is little experience regarding the routine cultural practices required for raising a “production plantation” of jatropha on such lands. Standardised seed material is currently not available in the market. The agronomic best practices as they exist now for spacing, pruning, fertilisation, irrigation and pest management in jatropha need to be tuned to the local terrain and climate, he emphasised.

“Logistical and mechanical support to increase the harvesting efficiency is necessary for the system to be viable, particularly in large scale, intensively managed plantations. The success of jatropha as a commercial crop would therefore depend on an orderly transfer and adoption of critical scientific information and improved agronomic practices,” he noted. Dr Francis spoke about the project undertaken by Daimler AG and the German government-owned DEG where two Mercedes-Benz C220 CDIs with manual and automatic transmissions and fuelled entirely with biodiesel made from jatropha oil made a cross-country trip from the factory in Pune through to Leh, without any adverse effects.

“Their performance was more or less indistinguishable from that of similar cars run on fossil diesel. Average fuel consumption was around 12km per litre in all cases, which was surprising considering the fact that jatropha biodiesel has a lower energy content compared to petro-diesel. The only negative aspect of jatropha oil that appeared in this study was that, being based on a vegetable oil, it tended to deteriorate if stored for long periods. Fuels that have been stored for more than 16 weeks performed slightly worse in the emission tests than freshly-produced fuel,” he pointed out.

Scope for vegetable oils

According to Avinash Kumar Agarwal of the Department of Mechanical Engineering, Indian Institute of Technology, Kanpur, considerable experimental work has been carried out in various countries for utilisation of vegetable oils in compression ignition engines. Vegetable oils and their derivatives in diesel engines lead to substantial reductions in sulphur, carbon monoxide (CO), polycylic aromatic hydrocarbons, smoke, noise and particulate emissions.

Furthermore, contribution of biofuels to the greenhouse effect is insignificant since carbon dioxide (CO2) emitted during the combustion is recycled in the photosynthesis process in plants. Vegetable oils, Agarwal described, have about 10 percent lower heating value than diesel due to its oxygen content. The kinematic viscosity of vegetable oils is however several times higher than that of diesel.

Higher viscosity of vegetable oils as against diesel leads to problems in pumping and atomisation, ring-sticking, carbon deposits on the piston, cylinder head, ring grooves, etc. In addition, higher viscosity is responsible for various undesirable combustion features of straight vegetable oils.

Since straight vegetable oils are not suitable as fuels for diesel engines, they have to be modified to bring the combustion-related properties closer to mineral diesel. Four well-known techniques are proposed to reduce the viscosity levels of vegetable oils, namely heating/pyrolysis, dilution/ blending, micro-emulsion and transesterification, explained Agarwal.

Potential of biobutanol

Demand for cleaner and sustainable alternative fuels for vehicles is growing worldwide in the wake of environmental concerns and rapid depletion of petroleum stocks.

Alcohols like methanol and ethanol have been tried in internal combustion engines in various forms including fumigation, dual-fuel and blends etc. Recently butanol, produced by fermentation, known as biobutanol, has emerged as a new alternative fuel for spark ignition engines.

In a paper prepared by MK Shukla, AK Jain and SK Singhal of the Indian Institute of Petroleum (IIP), Dehradun, it was mentioned that the most valuable and versatile liquid energy carriers are ethanol and biodiesel. However, other solvents including butanol are equally useful and, for special purposes, superior to ethanol. Butanol could gradually replace petrol as well as diesel due to its high energy content, miscibility, better combustion characteristics, low volatility and other positive qualities. Describing its fuel properties, Sunil Pathak of IIP explained that butanol can be mixed with petrol or diesel fuel in any proportion without phase separation.

Ethanol and butanol can be mixed in higher ratios with petrol for use in existing cars without the need for retrofitting as the air-fuel ratio and energy content are closer to that of petrol. The kinetic viscosity of butanol is several times higher than that of petrol and about as viscous as high quality diesel fuel. Butanol, he noted, is a very versatile fuel and a fuel extender in both petrol and diesel engines.

Pathak concluded that butanol is a clean alternative fuel for SI engines. However, unless cost competitive technologies are in place, it is difficult for butanol to establish itself as a transportation fuel. Also, before actually putting butanol to use as an alternative fuel, detailed material compatibility studies and its effect on human health have to be evaluated. Given proper research and governmental policy aid, butanol has the potential to emerge as an alternative fuel.

Overall, what is clearly established is that biofuels have much lower emissions and no net carbon dioxide emissions. They are not dependent on fossil fuel resources and some will run in unmodified engines. But the fact is that they are difficult to obtain and some cars cannot run on them without modification. And the amount of land needed to produce the plants to make the fuel in suitable quantities may be prohibitive. The expert view is that biofuels will conserve fossil fuel stocks, but viability will depend on availability and cost. In the final analysis, biofuels certainly have a future, but it is unlikely we can ever be totally reliant on them.