Earning in place of burning

Certain large- and small-scale tech-based methods of putting paddy stubble to use so that farmers, industries, and governments gain, are already in place, while others require due emphasis

- RAJWINDER SINGH & MAHESH PATEL

Paddy straw burning is considered a contributing factor to the dense haze that envelops the national capital and neighbouring states of Punjab, Haryana, and Uttar Pradesh during October and November each year.

In recent years, the Union as well as state governments have imposed multiple rules and regulations to dissuade farmers from stubble burning. Measures such as subsidies have also been introduced to promote crop residue management machines like Happy Seeder. Yet, these have had little impact on the farm fire cases. This shows an urgent need to identify alternative utilisation of rice straw and thereby increase the value of the crop waste for farmers.

Here are some technologies that can help farmers, industries, and government gain from paddy straw, while mitigating the problem of stubble burning.

Large-scale technologies

Direct combustion: This facility burns the rice straw in particular conditions to eliminate the massive piles of rice straw, while at the same time making the generated heat available for cooking and other purposes. Although the calorific value of rice straw (15 MJ/kg) is comparably less than that of petrol (45.8 MJ/kg) and diesel (54.5 MJ/kg), it is higher than the other agricultural waste. Currently, such facilities have not gained much attention in India.

Pyrolysis and gasification: These two technologies involve the burning of rice straw for its conversion into fuel in the form of a gas with high heating value. In pyrolysis, rice straw is placed in a system with a temperature range of 200–760 degrees Celsius where it is processed in the absence of oxygen. In the case of gasification, the temperature could range between 480–1,650 degrees Celsius along with some restricted supply of oxygen.