To help sugar cane farmers with excess stocks, the government in 2007 allowed companies to directly make ethanol from sugar cane juice for the first time and fixed the price of ethanol at Rs21.50 a litre. “By diversifying into related segments, sugar firms not only insulate themselves from price volatility, but also earn carbon credits and avail (of) income tax benefits from power generation,” said R. Sreesankar, head of research, IL&FS investmart Ltd, a brokerage firm, in an interview to Reuters.
Theory and practice
Getting cellulose from bagasse involves a step-by-step separation of long chains of sugar polymer molecules and its lignin components.
NCL scientists have perfected a steam treatment in which the lignocellulose is steamed in a reactor at a high pressure and at a particular time, the pressure is suddenly eased. “That shock blasts the bagasse into its constituents and thus in a single shot, we get nearly 99% pure cellulose, after which the chemical treatment begins for further purification,” said Varma.
According to data from agriculture ministry, the country produces nearly 300 million tonnes of sugar cane, a third of which, according to CSIR estimates, results in bagasse.
Several sugar mills in the country already use bagasse as fuel for their power mills. “It’s an excellent way to use the bagasse. We are doing that too,” said Somaiya. “But eventually we hope that is, so to say, the least best use of bagasse.”
To further enhance the productivity of the biorefinery, NCL and Godavari want to produce L-lactic acid, the useful form of lactic acid, from sugar cane juice. L-lactic acid is a base organic compound that’s widely used in the pharmaceutical and food preservatives industry. The technology for this has been developed by another group at the NCL.
“We’re helping farmers add value to sugar cane. While sugar cane juice, as of now, has only an edible benefit to it, we’re helping them with an alternative,” said Sanjay Nene, an NCL scientist involved with the lactic acid programme.
“Most of our lactic acid is imported,” he said.
Part of the sugar cane biorefinery, the lactic acid facility is expected to scale up to an annual 300 tonnes by the end of the year, Nene added.
Across the globe, policy makers as well as scientists have blamed governments and affiliated agencies for encouraging their farmers to grow crops for fuel rather than food and contributing to the recent global food crisis.
“So the real challenge,” said Varma, “would be to ensure that the fuel and all value-added products are not at the expense of food. We are the second largest producer of sugar cane in the world, and nearly a third of all sugar cane ends up as bagasse. So with an annual 90 million tonnes of bagasse, we are talking huge potential.”
The ethanol rush
It might still prove elusive. But separate teams of scientists at NCL, along with researchers at Delhi University, IIT Bombay and other CSIR labs such as the National Institute for Interdisciplinary Science and Technology, Thiruvananthapuram, and the Institute of Microbial Technology, Chandigarh, are testing strains of some fungi and other organisms, and zeroing on enzymes that will break down bagasse into ethanol.
Though the basic principles of deriving ethanol from cellulose are known, they’re not yet financially viable and research institutions, worldwide are looking at ways to cut production costs.