Stubble & the biomass magic bullet

PADDY stubble burning by farmers remains a problem this season despite the policies and measures taken by the government, including incentives and punitive measures, as well as awareness campaigns by civil society and voluntary action by farmers. The challenge persists in Punjab, Haryana and western Uttar Pradesh, contributing to poor air quality in this region.

We focus on Punjab, where farmers produce about 24 million tonnes of paddy, producing about 20 million tonnes of paddy straw as a byproduct, which can either be incorporated in the soil (in situ) by ploughing it back or utilised outside the field (ex situ) by cutting, baling and transporting it for use outside. About 1 million tonnes of this paddy stubble is used as animal fodder, 13 million tonnes is managed in situ and 6 million tonnes ex situ for purposes such as factory boiler fuel, compressed biogas, bioethanol and power generation. However, this data may not be reliable because a portion of the paddy stubble continues to be burned in the fields after paddy harvesting.

About 1.17 million tonnes of paddy straw is used in Punjab to generate power at 11 plants with a total capacity of 101.5 MW (megawatts). Some straw is converted into briquettes for mixed use in the state's coal-based thermal power plants. Can the government facilitate the setting up of more biomass-based power plants to utilise paddy straw? It would perhaps have financial implications for the Punjab State Power Corporation Ltd (PSPCL). As per the order of the Punjab State Electricity Regulatory Commission (PSERC), biomass power costs Rs 8.52 per unit when purchased by the PSPCL from the biomass power plants. This cost is significantly higher than the average cost of purchasing renewable power, which was Rs 6.76 per unit last year.

Now, considering that the electricity consumption in Punjab last year was about 60,000 million units, if the PSPCL were to agree to purchase biomass power from 500 MW of newly installed capacity, the additional cost per unit would be Rs 0.10 to 0.125. Further, if 500 MW of new plants are set up over five years, it would lead to an annual increase in power costs of only 2-2.50 paise per unit. This increase is comparable to the cost implications of the current mandate for thermal plants to use biomass briquettes for power generation by mixing them with coal.

Technological advancements have largely resolved the issue of boiler choking in biomass power plants using paddy straw as feedstock. Hence, the time may be right to invest in new biomass generation capacity based on paddy straw. If paddy-straw-based biomass power-generating plants of 500 MW are set up over five years, it will enable the annual utilisation of about 5-6 million tonnes of straw.

If each such power plant has a capacity of 10 MW, it would consume 1,20,000 to 1,40,000 tonnes of straw, generated over an area of about 20,000 to 25,000 hectares. Therefore, it is practical to 'reserve' an area with a radius of about 10 km for each power plant.

The location of such new plants will matter since paddy straw is difficult to transport due to its bulk; the plants will need to be spread out across the state's paddy-growing regions, roughly 18-20 km apart. Each plant must also be located near an existing or proposed 66-kv power grid substation to facilitate easy power evacuation and reduce transmission losses.

The additional cost of power to consumers will be offset by several benefits, including cleaner air. An investment of about Rs 4,000 crore, employment for about 10,000 persons (including paddy straw aggregators) and an additional income of Rs 12,500 per hectare to farmers are additional benefits, as is the enhanced capacity for renewable energy generation in the state.

We suggest that Punjab should promote 500 MW of biomass power generation capacity over the next five years, enabling additional ex situ management of 5-6 million tonnes of paddy straw. Given the issues around the cost of biomass power, the aggregation and storage of paddy straw, the reservation of paddy-growing areas for each generating plant, the offtake of power, etc, this programme will require active facilitation by the state government. Multiple state agencies need to collaborate effectively to reach the goal.

While Innovate Mission-Punjab can inform and encourage entrepreneurs to invest in new biomass power plants using the latest technology, Invest Punjab can facilitate regulatory clearances. The PSPCL can offer standard power purchase conditions, and the Department of Agriculture can earmark the minimum distance between such new plants to avoid 'poaching' of paddy straw. Punjab Energy Development Agency (PEDA) and the district administrations can facilitate clusters of local entrepreneurs who aggregate, manage and store paddy straw.

Thus, along with other ex-situ management initiatives, such as compressed biogas, bioethanol and industrial uses, we can achieve the target of clean, sustainable management of paddy straw.

Part of the solution to stubble burning lies in biomass-based power generation. What makes this solution feasible is the abundant availability of paddy straw, improved access to subsidised rakers and supply chains for biomass-based power plants and additional income for farmers. The challenge would be to ensure that consumers can comfortably absorb the modest increase in power costs, supported by a well-coordinated, collaborative institutional effort.

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