Fighting the smog in India: biomass instead of air pollution

Year after year, rice and wheat fields burn in many regions of northern India – and dark smoke clouds pollute the already smog-polluted air of Delhi even more. Now, a new technology from thyssenkrupp could put an end to the so-called “stubble burning” that was born out of the plight of local farmers. And it could also supply the Indian power grid with green energy.

While Europeans like to take a time out for a walk in the cold, fresh autumn air during the last months of the year, many people in Delhi, India, leave their homes during this time only with a respirator mask. One reason for this is the smog that shrouds the metropolitan region 365 days a year. A study by the University of Chicago shows how dramatic the situation is: In Europe, the life span is shortened by an average of one to two months due to fine dust pollution – in India, it is 4.3 years. It is the country where many of the world’s most polluted cities are located.

However, it is the November days in particular when the smog of the megacity becomes even denser and more oppressive. As soon as the rice fields in the states of Punjab, Haryana, and Uttar Pradesh bordering New Delhi have been harvested, the fine dust from traffic mixes with the black smoke from millions of tons of plant residues that go up in flames within a few days. The cultivated farmland for rice, a sacred food for many Indians, burns – lit by the owners themselves.

Phenomenon stubble burning: for Indian farmers, it’s about their existence

The federal state of Punjab is considered the breadbasket of India. About 140 million tons of paddy rice are harvested here alone annually . The reason why local farmers set their fields on fire after harvesting is that they sometimes have to harvest up to three crops a year, and have to prepare their fields for the new seed between harvests. This leaves farmers with only a minimal window of opportunity. Compared to the expensive and time-consuming clearing of the fields by special agricultural machinery, burning is much cheaper and more efficient.

Stubble burning is a relatively new phenomenon: While Indian farmers were still harvesting their crops by hand until the 1980s, more and more fields were left with plant stubble about 30 centimeters high after the introduction of the combine harvester . There are two million farmers in Punjab alone, most of them living at subsistence level. Despite government support, few can afford new field machines to speed up the time-critical work. Out of necessity, the majority choose fire to destroy the stubble in time – even if the soil quality deteriorates year after year as a result.

Politicians are trying to reduce the fires and the oppressive smoke with a number of measures . However, despite the official banning of this practice, which is harmful to the environment and humans, despite digital appeals and educational campaigns and financial injections for field machines, every year the smoke is still spreading through the cities.

Biomass technology: green energy instead of burning fields

For the stubble burning to end in the long term, innovative technologies are needed. This can only succeed if the farmers are not forced to set fire to their land because of poverty, do not have to fear punishment, but rather receive economic incentives. And action is being taken : More and more companies are looking for ways to buy plant residues from farmers and recycle them – into bio-plastics, paper, furniture, or as raw materials for green energy production. An Indian team of experts from thyssenkrupp has also set itself the goal of transforming the plant residues into a valuable resource for the transformation of energy systems.

For this mission, they bring a lot of experience with them: Especially in India, thyssenkrupp has been working for decades on the question of how biomass technologies can make local industry more sustainable. “Our commitment to clean energy based on biomass goes back to the beginnings of our business activities in India. Back in the late 1970s, we started manufacturing boilers for sugar factories,” says Vivek Bhatia, CEO of thyssenkrupp Industries India.

“Our boilers processed sugarcane bagasse, a biofuel that was still a waste product for the sugar factories at the time. We were the first to bring about the concept of cogeneration for the Indian power industry. In the late 1980s, we moved our focus to eco-friendly solutions for the combustion of fuels with low-quality value with much lower emissions compared to other technologies of the time. We have been at the forefront of offering highly efficient equipment for a wide range of industries, including the cement, mining, and mineral processing industries.”

Water-cooled vibrating grate: processing crop residues – without damaging biomass boilers

In particular, one special technology recently licensed by thyssenkrupp from its Danish partner Babcock & Wilcox Vølund A/S could greatly contribute to the end of stubble burning now: water-cooled vibrating grates. The biomass, in this case the harvest stubble, is first shredded and then evenly distributed on a continuously vibrating grate. A water-jacket system provides cooling. The remaining ash is collected and disposed of underneath the grate. At the end of the process, climate-neutral energy is produced from the plant remains from the fields.

In contrast to conventional technologies, the central biomass boiler is specially designed for harvest residues that are difficult to process – and thus unique on the Indian market. “The fertilizer fed to the crops, biomass from wheat and rice, is rich in chlorine, potassium, and alkaline. Because these deposits are highly corrosive, they damage the inside of the boilers. Ultimately, this leads to the functional failure of the system because proper heat transfer is prevented,” explains Vivek Bhatia. “With our technology, we can handle even such difficult biomass and ensure that the boiler design is safeguarded from a long-term operational perspective, meeting all emission norms – with no additional costs for briquetting as the biomass can be fed directly into the grate for combustion.”

Durability instead of corrosion damage: the first customer was convinced quickly

The team around Vivek Bhatia has already convinced the first Indian customer with its promising technology: The food manufacturer Sukhbir Agro Energy Ltd. (SAEL) will install the water-cooled vibrating grates in two new high-pressure boilers that process a total of 80 tons of biomass per hour. Initially, SAEL relied on conventional systems, but due to the corrosion damage inside its boilers and the resulting failures, thyssenkrupp’s innovation quickly landed on the Delhi-based company’s table. In the future, the new SAEL plants will generate energy from rice straw. Rice straw from the fields of Punjab, Haryana, and Uttar Pradesh are no longer burnt, but collected, sold, and used sustainably.

Sustainable solution for climate-neutral energy that avoids smog

“For a long time, the burning of crop waste in the fields has been a major cause of winter air pollution in northern India. Now, we have a sustainable solution to this issue by utilizing this crop waste for clean energy generation.” For Vivek Bhatia, this is a win-win situation: “Farmers are able to earn more through sale of their waste biomass. Consumers in turn have the benefit of carbon-neutral energy by biomass power generation. At the same time, we are able to create local jobs.” In the future, the boiler system promises to inspire customers in other Asian countries to convert biomass into energy in a more efficient and durable way, for example in Sri Lanka, Bangladesh, and Thailand.

But first and foremost, the citizens of New Delhi are now hoping that their air will soon contain considerably fewer toxins. In addition to thyssenkrupp’s new biomass systems this hope is also nourished by another extremely encouraging development: In May 2019, the Punjab Pollution Control Board reported that the number of burning stubble fields had clearly decreased compared with the previous year . It seems that the educational work of the Indian government is having an effect for the first time. In conjunction with thyssenkrupp’s new biomass technology, the sky over Delhi is gradually clearing up. And not only in a figurative sense.