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November 14, 2019

From stubble-burning to smog


November 14, 2019

Smog has arrived once again – as it comes down this time of the year. Children have not gone to school. Air flights and normal road traffic will probably be disturbed.

We had discussed in this space earlier the role of petroleum, automotive vehicles and road traffic in causing air pollution and smog in Punjab and elsewhere. In the following, we will deal with the role and impact of stubble burning and will explore ways and means of handling and mitigating the issue as well.

The issue is full of controversies. On both sides of the border in our region, blame is being leveled that the stubble burning pollution is travelling from the other side. Both may be right as the area is contiguous and the wind direction keeps changing.

At least in India, farmers are downplaying the role of stubble burning in causing smog and are shifting the blame on other sectors. They are also contesting the role of machines in recycling stubble into the soil – terming it ineffective, expensive and unaffordable. High courts have been issuing edicts banning stubble burning but the ban has not been effective. A subsidy of IRS100 per quintal (100 kg) has also been ordered by the courts to help farmers meet the expenses of machinery in recycling the stubble.

There is no doubt that stubble burning is not the sole reason for smog. Traffic emissions, brick kilns, industrial pollution especially burning of dirty fuels and no pollution controls, dusty construction activities, all are contributors to the problem. However, in the autumn when rice is harvested on both sides of the border and the stubble has to be cleared within fifteen days in order to be able to sow a new crop – both the volume and the time enhance the intensity of the problem. So the cheapest and fastest way is to burn the stubble.

Expensive equipment and technology is around which can be used to clear the stubble without burning it. But only rich farmers can afford it. However, without a useful use of the stubble, nobody would have the incentive to invest in it. Indian Punjab alone produces 20 million tons of stubble, most of which is burnt in a month in October. A recent study in Pakistan estimates stubble burning at some two million tons appears to be an underestimation for a six million ton annual production of rice.

Overall, 60-80 million tons of agricultural waste and residue is generated in Pakistan annually. This can be a resource rather than a liability. It contains energy as is readily seen by the burning flames. Instead of wasting it, it can be usefully employed and can be used in producing electricity, and in the industrial and domestic sectors. Bio-fuels are a new product that is being increasingly produced from rice straw and other agricultural waste.

Raw stubble is, however, a liability and its burning is inconvenient and wasteful. For efficient and convenient use, it is converted into briquettes or pellets. The biomass is to be dried, crushed and pressed into pellets with or without the help of binding additives. Densification reduces volume, reducing transportation costs, and increases volumetric calorific value. It also slows down burning; raw biomass burns too fast making it uncontrollable and wasteful. Also storage becomes easier reducing volume requirements and increasing stackability. While biomass/stubble may be generated in a short time, it cannot be consumed instantaneously; it has to be stored for later sustained consumption.

Raw biomass is currently used by the rural poor in domestic cooking and even heating. In its raw form, it causes indoor pollution affecting women especially. In pellet form, it is less polluting and manageable. All rural areas are not equally endowed agriculturally. Pellets can make biomass transportable and tradable and converted into a saleable commodity. Currently, it has no value, except in some special cases such as Bagasse. If it has a value, it won’t be so mercilessly burnt as stubble is burnt currently.

Only 20 percent of the population in Pakistan has access to gas where a pipeline network is available. In other areas, charcoal, LPG and kerosene are used which are much more expensive. Gas is subsidized (cross subsidy) to small and medium consumers. Gas availability is going down and it is getting costlier, especially due to the advent of LNG.

Biomass pellets can be affordable. Biomass pellets have almost the same energy content as Lignite (Thar coal). Thar Lignite is being produced at a cost of $47 per ton. The government of Pakistan could encourage small, medium and large-scale utilization of biomass including stubble – paddy waste. Small pellet producing plants can be installed on farmlands. Model and demonstrating plants could be installed and easy credit terms provided.

Third parties like the cement industry can install medium to large sized plants. Some progressive cement producers are already lifting municipal solid waste to burn in their kilns. Brick kilns can be encouraged to use biomass briquettes in place of coal and other dirty coals. Thus biomass briquettes can be introduced as another fuel in the fuel market of the country which would improve the quality of life and contribute to rural economies. A curse can be converting into blessing.

Ethanol production from food crops (first generation technology) is not new. However, producing ethanol from Cellulosic materials like rice straw is a relatively new phenomenon. Rice straw can now be converted into biogas and bio liquid fuels. In Italy, Romania, the US and Brazil, rice straw is utilized in producing bio-ethanol. Ethanol is mixed with gasoline in without affecting engine performance or requiring modification.

Policies are in place in most advanced countries requiring 5-10 percent ethanol in gasoline. It is a separate matter that Pakistan produces ethanol but exports it. India is going ahead with several bio-refineries base on rice straw. It is time to examine the feasibility of a similar bio-refinery in Pakistan. It would produce much required petrol, save foreign exchange and would provide incentives to farmers not to burn rice straw. However, varying and low oil prices have put all such proposals into question. Bio-char (a fertilizer) can also be produced from rice straw and other agricultural waste. Gas and bio-CNG is another option and attractive enough in the context of falling local gas production. Agri-biomass including raw straw is often mixed with sewage to produce biogas. This partly solves sewerage issue as well.

Economics is the final constraint in technology choice. Economics varies regionally with location and resource endowment. If smog and pollution health effects are internalized in economic calculations, the aforementioned solutions may possibly become more attractive.

Finally, it is said that it is easier to build and finance a bio-refinery than to collect rice straw and biomass from the farmer, as he has his own constraints and economics. Capital investment in collection by third parties and conversion of rice straw into useful products as mentioned earlier offers a practical solution. If all of it is found too difficult to implement, de-zoning, prohibiting rice production near large cities may have to be introduced. There can be alternative crops. Health is more important than money.

The writer is a former member of the Energy Planning Commission and author of ‘Pakistan’s Energy Issues: Success and Challenges’.

Email: [email protected]