Pre-treated pine needles produce more biogas, prevent forest fires

Kolkata, Aug 4 (IANS) Pre-treatment of pine needles -- a common source of domestic fuel in the Indian Himalayas -- with a microbial mix can enhance biogas production and help prevent forest fires, scientists say.

Pine needles are a difficult forest waste. They cannot serve as fodder and do not lend themselves to decay like other biomass and are a major source of wild forest fires as they are highly inflammable.

"Additionally, dry pine foliage stops water from being absorbed by the soil and thus causes depletion of groundwater table. But they are a good source of biofuel and by harnessing them for sustainable energy, one can prevent forest fires," Ravi Pratap Singh of the department of Farm Machinery and Power Engineering College of Technology, G.B. Pant University of Agriculture and Technology, Uttarakhand, told IANS.

To enhance utilisation of pine needles as a green energy source, the scientists deployed Trichoderma and Pseudomonas species.

It was found that a biomethane yield of 21.3 litre/kg pine needles can be obtained from pretreated pine needles which was 300 per cent higher compared to untreated pine needles substrate, the researchers said in the study published in Current Science in July.

Pine needles are categorised as lignocellulosic biomass (plant dry matter) which is still a predominant fuel harnessed for domestic purposes in the mid-altitude villages of the Indian Himalayas region (Uttarakhand, Himachal Pradesh and Jammu and Kashmir) which produces about 159 lakh tonnes of pine needles every year, said Singh.

Pre-treatment renders the chemical structure of the pine needles accessible to microbial activity to achieve high biogas yields.

"The bio-treated pine needles can be mixed with available cattle dung and fed to biogas plants in nearby village to generate biogas rich in methane," Singh said.

The present paper (co-authored by R. K. Dwivedi and TK Bhattacharya) is an outcome of a series of ongoing research involving variety of additives or treatment including other species of Trichoderma.

"Scientists are taking interest in exploration of naturally fallen foliage for generation of biofuels through briquetting, gasification, pyrolysis, alcoholic and anaerobic fermentations to produce briquette, producer gas, bio-oil, bio-alcohol and biogas. Out of these, biomethanation seems to be quite economical as each of its end product is useful, as biogas, as biofuel, digestate/sludge which can be used as manure,a Singh added.