During different harvesting seasons, crop residues of rice, wheat, sugarcane, maize, cotton, soya bean, mustard, among others, are burnt in the crop lands in various areas of India. More than 683 million tonnes (Mt) of crop residues of different crops are produced, of which a major part is used as fodder, fuel, and in various industrial processes.
Despite this, about 178 Mt of surplus crop residues are available around the country. An estimated 87 Mt of surplus crop residues is burnt in different croplands. Some studies have estimated that more than 8.5 Mt of carbon monoxide is emitted to the atmosphere during the burning of crop residues. Studies have also reported the several ill-effects of crop residue burning on soil organic carbon and fertility including reduction in the productivity in the long run.
On an average, 1.8 to 2.5 times higher rice straw is produced compared to grains. The usage of mechanical harvesters leaves at least 15 cm of standing crop in the field along with large amount of straw and this straw bed is not suitable for the establishment of wheat seedlings. The narrow timeline between rice crop harvest and sowing of wheat seed vis-à-vis intensive use of mechanical harvesters force farmers’ to burn crop residues in preparation of the land for the next crop.
Moreover, certain rice varieties, such as basmati, are always hand-harvested; while certain varieties such as parimal are machine harvested. The variety of wheat also affects the burning of rice crop residues as some wheat varieties (e.g. CSW18) require early sowing.
Almost no use and no attractive monetary return of the surplus crop residues and the labour cost associated with the collection of crop residues demotivate farmers in collecting the residues from the field and instead they burn it in situ.
In situ management of crop residue
During March 2018, the Cabinet Committee for Economic Affairs approved Rs 1151.80 crore under the central sector scheme (CSS) on ‘promotion of agricultural mechanisation for in situ management of crop residues in the states of Punjab, Haryana, Rajasthan, Uttar Pradesh and NCT of Delhi’ to tackle air pollution and subsidise farm machineries required for in-situ management of crop residues.
Various opportunities are available for managing paddy residues as evident from Figure 1. Accordingly, different variants of machineries were included in the scheme for individual farmers and through custom hiring centre (CHC). However, in 2018–19, 16.9% of total rice straw residue (7.93 Mt) in Haryana and nearly 50% of total rice straw residue (20.17 Mt) in Punjab were burnt in situ.
Turbo happy seeders have been included in the above scheme with 50% subsidy, keeping in view its reported effectiveness in increasing wheat production under the rice–wheat cropping system. It is reported that 1 happy seeder can manage 7–8 acres of rice straw residues for the sowing of wheat seed per.
During 2018/19, 9758 happy seeders were distributed in Punjab, and 2376 happy seeders in Haryana; in 2019–20, 2936 and 1500 happy seeders were distributed in Punjab and Haryana, respectively. Accordingly, these happy seeders addressed about 50% of unmanaged paddy crop land area in Punjab (19.3 million ha) and about 42% of paddy crop land area in Haryana (7.31 million ha).
The 6000 combined fitted with Super–Straw Management System (S-SMS) can, likewise, harvest 0.7 million ha at the rate of 12–15 acres daily over 25 days. It becomes evident that these machineries are not sufficient to manage the entire paddy crop residue within 25–30 days time. Farmers’ have however raised concern about investment in one machine that can be used only during one season rather than investing on a machinery, such as tractor, that can be used year long.
Managing crop residue ex situ
The existing in situ crop residue management machineries can manage only upto 2 to 4 tonnes/ha of crop residues while far higher crop residues are produced. Keeping this obligation of in situ crop residue management in view, governments have formulated different opportunities to manage the crop residues ex situ:
- The Punjab government announced ‘New and renewable sources of energy policy’ in 2012 to promote renewable energy in the state. » Under this policy, a capacity target of 600 MW from biomass and 500 MW from cogeneration (both bagasse and non-bagasse) has been set by 2022. However, only 62.5 MW has been commissioned till date through 7 power projects which annually use 0.5 Mt of paddy straw. In addition, another 58 MW projects are in various stages of planning and implementation, which can utilize 0.72 Mt of paddy straw annually. The Punjab Energy Development Agency (PEDA) has invited expression of interest from the interested project developers for setting up of 150 MW capacity 100% rice straw-based biomass power plants on viability gap funding-based competitive bidding.
- The Haryana government formulated the Haryana Bioenergy Policy 2018 to utilise its surplus crop residues to generate bio-CNG/bio-manure/bio-fuel. It is proposed to achieve a target of 150 MW biomass-based power generation (or equivalent) by 2022. The Haryana Renewable Energy Development Authority (HAREDA) agency, which promotes renewable energy in the state, has identified and awarded a cumulative of 50 MW capacity biomass power projects based on 100% paddy straw technology in the districts of Fatehabad, Kurukshetra, Jind, and Kaithal. These biomass power plants will be able to utilise about 0.3 Mt of paddy straw annually.
- Central Electricity Authority (CEA), Government of India, has issued a policy advisory for biomass utilisation for power generation through co-firing in pulverised coal-fired boilers (CEA 2017). The document highlights successful demonstration of co-firing of 7% blend of biomass pellets with coal by NTPC. In order to promote the use of biomass pellets, all fluidised bed and pulverised coal units (coal-based thermal power plants) of public- and private power-generating utilities are advised to use 5–10% blend of biomass pellets, primarily agro residues, along with coal. With the overall thermal power generation capacity 203 GW (CEA 2019), the estimated daily biomass pellets requirement would be about 146,498 tonnes (assuming 2.75 lakh tonnes of biomass pellets for 7% blending in a thermal power plant of 1000 MW capacity). This would utilise about 53.5 Mt of crop residues annually, which is about 30% of the total annual surplus crop residue in the country.
- The Ministry of New and Renewable Energy (MNRE), Government of India launched a programme on energy from agricultural waste/residue in the form of biogas–bio–CNG, enriched biogas/power. Projects based on biowaste from urban and agricultural waste (paddy straw, agro-processing industry residue, green grasses, etc.) are eligible for Central Finance Assistance (CFA) in the form of capital subsidy and grant-in-aid under the programme.
- The Ministry of Petroleum and Natural Gas (MoPNG), Government of India brought out the National Policy on Biofuels on 8 June 2018. The policy promotes the target of 20% blending of ethanol in gasoline by 2030. The policy categorises biofuels as (i) basic biofuels viz. 1G bio-ethanol, bio-diesel and (ii) advanced biofuels viz. 2G ethanol, bio-CNG, etc. Under the policy, a viability gap funding for 2G ethanol refineries of Rs. 5000 crore will be made available in 6 years besides additional tax incentives and higher purchase price (in comparison to 1G ethanol). Also, oil marketing companies are in the process of setting up twelve 2G bio-refineries with an investment of Rs 10,000 crore.
The Indian Oil Corporation (IOCL) is setting up 100 kilo litre per day (KLPD) of ligno-cellulosic 2G bioethanol plant at Baholi in the Panipat district of Haryana with an investment of Rs 700 crore. It is estimated that about 0.2 Mt of agricultural biomass will be utilised annually by this plant.
Hindustan Petroleum is setting up another 100 KLPD ligno-cellulogic 2G ethanol plant at Nasibpura in the Bathinda district of Punjab. This plant will utilise paddy straw as the main feedstock with an investment of about Rs 1000 crore. It is estimated that the plant will utilise about 500–600 tonnes of paddy straw per day.
The estimated utilisation of surplus crop residues under different government policies are given in Table 1. However, still large amounts of non-addressed surplus crop residues (about 120 Mt) are available. The successful implementation of the above initiatives is also required to develop a road map for sustainable utilisation of crop residues. There are different opportunities to manage crop residues; however, it is required that a road map be developed by which sustainable utilisation of crop residues occurs through different management options.
Prescribed Strategy
- Crop rotation in the IGP region needs to be reevaluated by encouraging farmers to other cropping cycles rather than rice–wheat cropping system. $
- Conservative farming needs to be promoted all over the country (like lower lignin ((<20%) crops) for rice, wheat, maize, sugarcane to reduce soil compaction and to maintain soil fertility: —*Crop residues of 30 to 40% of lower lignin content (<20%) should be left in the crop land after harvest and managed with in situ crop residue management machineries.
*Crop harvesting machineries need to be developed that retain 30–40% crop residues in the field while bailing the rest of the amount.
Utilisation of crop residues in state-level power plants: The total installed capacity of state-owned thermal power plants in Punjab and Haryana is about 2640 MW and 3160 MW, respectively (Table 2). The state governments can mandate existing thermal power plants to use 5–10% paddy straw in co-firing mode which can then utilise about 0.72 and 0.87 Mt annually.
Enable mechanism of crop residue biomass aggregation: The central government and state governments of India have notified several policies to manage the surplus crop residues. Additional policies are still needed on crop residue collection and aggregation that will encourage private investment in crop residue collection business and further provide options to the farmers in disposing their crop residues and build viable business models to establish a crop residue supply chain mechanism. This will allow the private sector in investing in processes to crop residue valorisation through production of briquettes, char briquette, paper, tableware, fabric production, etc.
Some of the specific recommendations are as follows:
- Create infrastructure for setting up biomass depots for the storage of bailed crop residue
- Mandate state/national organization (such as NAFED, HAFED PAIC) to aggregate crop residue
- Create special credit line/scheme for financing of farm equipment and high working capital for private sector participation
- Create market for crop residue-based briquettes: a) Decentralised model of production of crop residue briquettes or char briquette involving farmer producer organisations (FPOs), farmers’ cooperatives, etc. need to be prioritised. b) The use of crop residue briquettes or char briquette in local industries and hotels/dhabas need to be promoted.
Decentralised use of crop residues: Gasification of coal and biomass has been known for over a century. India is one of the few countries having an active research and demonstration programme on small-scale biomass gasification technologies. In a gasifier, solid biomass fuels (wood, agriculture residues, briquettes, etc.) are converted into gaseous fuel (producer gas) by a series of thermochemical processes. The producer gas has a calorific value of about 1000 to 1200 kcal/Nm3 and consists mainly of carbon monoxide, hydrogen, and nitrogen.
The producer gas can be used as fuel in internal combustion engines to produce mechanical power and electricity. About 1.2 to 1.4 kg of biomass is required for producing 1 kWh of electricity (using 100% producer gas engine). The gasifier packages having capacities ranging from 10 kW to 1000 kW for various applications include those for electricity generation, by running an engine generator on producer gas; mechanical shaft power when the producer gas is used as a fuel in an engine and the engine is directly coupled to the appliance (e.g. water pump, grinder) or thermal applications in which the producer gas is directly burnt in a stove, furnace, or boiler to running cold storage.
Crop residues can be utilised as fuel for running biomass gasifier for trigeneration applications including electricity, agro-processing, and running decentralised cold storage at the village level. This can also provide farmers an alternate option to shift to horticulture crops for which farmers currently are reluctant owing to limited cold storage capacity at the local level. A 250 kWe capacity biomass gasifier plant can utilise about 2000 tonnes of paddy straw annually and support 50 tonnage refrigeration (TR) cold storage facility besides producing electricity.
A suggestive sustainable business model for the utilisation of the crop residues is developed based on the discussions above (Figure 2).
Village-level cold storage with gasification unit; V1 to V5 are villages; CRC: Crop residue company under FPO. Solid arrow indicates crop residue/crop residue based product flow and dashed arrow indicate flow of money.
The cost-benefit analysis of various options for management of agricultural residues is being carried and will be further discussed with the stakeholders for finalisation.
Source: The Energy and Resources Institute (TERI), teriin.org
