Handling agri waste the remunerative way

Vijay C Roy

WITH a view to curbing stubble fires, the Punjab Government decided in 2013 to finetune its policy for the management and utilisation of paddy straw to focus on a multi-pronged, integrated approach.

One of the technical measures highlighted at that time was straw mulching in the fields by using specially designed machines. In this procedure, the residue is assimilated into the field itself and is thus used to increase the nutrient value or fertility of the soil. The in situ mechanism of paddy straw was expected to reduce fertiliser consumption by 25 per cent.

The second measure pertained to the use of straw. During a meeting in 2013, the Punjab State Council for Science & Technology (PSCST) told the state government that paddy stubble can be converted into briquettes which can be used as a substitute for coal or furnace oil to fire boilers and brick kilns. The fuel included 60-70 per cent paddy straw and the rest were other forms of biomass. Having got encouraging results, project proposals were submitted to the Centre. In 2016, a grant was received from the Ministry of Environment to set up two demo fuel plants to convert paddy straw into briquettes. One of the plants was commissioned in Moga in 2019 and the other will be commissioned soon.

Keeping in view the increasing menace of burning of crop stubble, several initiatives for its proper management have been taken, but still the problem persists in Punjab and Haryana. Both states together produce around 35 million tonnes of paddy straw every year. Some estimates say around 80 per cent is burnt. Farmers set afire a major portion of the straw due to lack of affordable solutions. Its storage, collection and transportation is a costly affair. The straw has a useful heating value of 3,200 to 3,500 kcal/kg, which is closer to that of coal used for power generation in thermal power plants.

In Punjab, with the support of the Centre, over 50,000 machines have been provided on subsidy to paddy growers for the management of crop residue in the past two years, including happy seeders, Super Stubble Management Systems (Super SMS), an attachment with the existing combine harvester, choppers and mulchers, balers etc.

According to experts, there is a 20-day window available to the farmers after the culmination of paddy harvesting and the start of wheat sowing. During this period, these machines cannot cover the total area under these crops. The affordability of the machines is also a big issue.

Biomass units

Currently, at least a dozen biomass units are using paddy straw as raw material in the two states, besides a few cardboard manufacturers. Considering the biomass generation, the usage by the industry is minuscule.

Last year, during the Progressive Punjab Investors’ Summit, the state government invited investments from industrialists, citing huge potential for utilising paddy straw. “Almost 20 million tonnes of stubble is being produced every year, of which only a small portion is processed, leaving surplus with farmers who have no option but to burn it,” the then Additional Chief Secretary (Development) Viswajeet Khanna had told the gathering during the summit.

Straw-based projects

Paddy straw is an alternative to coal and crude oil for producing energy. The Punjab Renewable Energy Systems Private Limited (PRESPL) has set up a plant in Patiala district to convert paddy straw into briquettes. The plant, which has the capacity to handle 150 tonnes per day of straw, will be inaugurated soon. This will be entirely a straw-based unit. The total cost of the project is Rs 9 crore. The grant from the Centre is to the tune of Rs 65 lakh.

“This will be the first-of-its-kind project in Punjab. We will supply the briquettes to the industry as an alternative to coal and we will also use it for our own captive consumption as part of our backward integration plan,” says Lt Col Monish Ahuja (retd), managing director, PRESPL.

“We provide balers and chippers to the farmers to assist them in pre-processing the agricultural waste before it is transported to the company warehouse. Apart from providing raw material, the farmers are responsible for transporting the waste from their farms to the warehouses and then to the plant site using tractor trailers. They get paid for this effort,” he adds. “So, in a way, we are making them village-level entrepreneurs.”

The agricultural waste collected then goes to the briquetting facility owned by the company, and briquettes from these facilities are transported to the steam generation plants. At these plants, biomass briquettes are burned to form steam. This steam is then sold to industries. The steam generation plants are set up either inside such factories or nearby. By selling steam directly to the industry, PRESPL is also able to bypass the issues faced while working with the distribution company.

The company started biomass aggregation and supply in India in 2011. In March 2020, it commissioned the first-of-its-kind 100% raw biomass-fired boiler for steam generation and the sale of energy on a steam purchase agreement (akin to a PPA) for a 10-year tenure. The company will sell steam to industrial consumers by firing boilers from briquettes.

A2P (agri to power) Energy Solution Private Limited seeks to offer ways to deal with the pressing issue of stubble burning. It is working with farmers in Punjab by buying the crop residue and helping them earn additional income from farm waste by converting it into pellets which are then put to industrial use for fuel.

“Last year, we converted 1,400 tonnes of paddy waste into fuel pellets and sold it to industry to fuel their boilers,” says Sukhmeet Singh of A2P Energy. The company has a unit in Rajpura. The farmers can earn Rs 2,500-Rs 3,000 per acre by selling paddy straw.

Oil companies’ plans

Oil companies are proposing ethanol bio-refinery plants using paddy straw. Hindustan Petroleum Corporation Limited announced to set up a second-generation (2G) ethanol bio-refinery in Bathinda. Once operational, it will use over 400 tonnes of paddy straw per day in addition to other forms of biomass. In Haryana, the Indian Oil Corporation (IOC) has proposed to set up a 100-kilolitre per day capacity bio-refinery at Bohali village in Panipat. Once functional, it will use 700 tonnes of paddy straw daily and produce 100 kilolitres of ethanol per day. According to experts, there is a need to establish more plants that consume paddy straw and convert it into ethanol or bio CNG. The success of these projects calls for making them economically viable, so that the farmers get good prices for paddy straw.

IIT initiative

• In December 2019, Indian Institute of Technology (IIT-Madras) had announced academia-industry collaboration with Sukhbir Agro Energy Limited (SAEL) for technology development in thermal power generation using paddy straw as fuel.
• SAEL approached the NCCRD (National Centre for Combustion Research and Development) at IIT-Madras for a tieup to conduct research & development.
• Speaking about targeted outcomes of the collaboration, Satyanarayanan Chakravarthy, Professor in-charge, NCCRD, had said: “IIT-Madras will meet technical requirements such as design of the prototype boiler, conducting trials and providing the criterion for the design of new power plant boilers, while the whole project will be funded by SAEL.” Prof Chakravarthy had also talked about conducting trials in a laboratory-scale combustor.