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In our struggle to tackle climate change, reducing short-lived climate pollutants (SLCPs) must play a crucial role. SLCPs are potent emissions that include black carbon, methane, tropospheric ozone, and hydrofluorocarbons (HFCs) and are commonly associated with refrigeration, diesel-fuelled vehicles, and biomass burning. Despite their short persistence in the atmosphere with respect to carbon dioxide (CO2), they account for up to 45% of current global warming.

A recent webinar, organized by the Climate and Clean Air Coalition (CCAC), discussed approaches and opportunities to mitigate SLCPs in India in the different economic sectors. In India, where 68.7% percent of GHG emissions come from the energy sector (FAOSTAT 2018), one of the major sources of air pollutants is open burning of crop residues. While wheat residues are used as animal feed, rice straw are generally burnt in the fields, causing severe air pollution spikes. FAO recently carried out a study through the Bioenergy and Food Security (BEFS) Approach, to assess if rice straw can be turned into alternative fuels, thus avoiding open burning and ultimately reducing emissions.

A preview of this assessment, which is due to be published at the beginning of 2022, was presented at the CCAC webinar. In presenting a model of rice straw value chain to mobilize rice straw in Punjab, one of the regions where open burning is a major issue, FAO answered two questions.

How to collect rice straw?

In Punjab, around 15.4 million tonnes of rice straw are burnt in the fields and collection must be done in 20 days, the time available between rice harvest and wheat sowing. FAO developed a model value chain of rice straw and estimated the type of equipment needed and the total costs required to bale, transport and store the straw after it has been harvested.
The results suggest that large amounts of machinery and manpower would be needed and estimated that to mobilize 30 percent of the rice straw produced in Punjab an investment of around USD 309 million would be needed to collect, transport, and store it within a 20-day period.

Can rice straw be turned into alternative fuel?

In the context of India’s efforts to reduce imports of fossil fuels, the government’s bioenergy policy has specific targets to increase local production of bioenergy. This includes ethanol to achieve E20 blending by 2025, production of Compressed biogas (CBG) to replace natural gas used as transport fuel, and production of biomass pellets to cofire with coal in thermal power plants. The techno-economic viability assessment carried out by FAO highlighted that rice straw can be used to produce all three energy carriers. Of these, pellets and CBG production seem more viable, since 2G ethanol needs very high investment.

Conclusions

Rice straw is a valuable resource that can support India by increasing its local supply of energy while reducing its reliance on imports. In addition, mobilizing crop residues to produce alternative fuels would help India reduce its GHG emissions. With agriculture currently accounting for around 19.6% of total emissions, innovating the supply chain of one of its main agricultural residues’ productions would result in a reduction of GHG emission of about 12 million tonnes of CO2 equivalent and around 66 000 tonnes of PM2.5 emissions.