As the world grapples with climate change, volatile oil markets, and the urgent need for cleaner energy, two of the planet’s most populous regions—California and India—are rethinking what goes into their fuel tanks. Recent developments in both places highlight how local realities shape biofuel policies, with California leaning on higher ethanol blends to cut emissions and India debating a pivot to residue-based biofuels amid water scarcity and rural economic pressures.
In California, a groundbreaking study by the University of California, Riverside (UC Riverside) has paved the way for a significant shift in the state’s fuel policy. According to UC Riverside’s College of Engineering Center for Environmental Research and Technology (CE-CERT), increasing the allowable ethanol content in gasoline from 10% (E10) to 15% (E15) yields a tangible reduction in harmful vehicle emissions. The research, completed in 2023 and led by Professor Georgios Karavalakis, found that the E15 blend cut emissions of carbon monoxide, total hydrocarbons, non-methane hydrocarbons, and, critically, particulate matter—those tiny airborne particles that can deeply penetrate the human respiratory system.
“Ethanol helps provide a much cleaner combustion because it has oxygen,” Karavalakis explained to Phys.org. “That’s why you have reductions in particulate emissions and in ultrafine particles, which are the very, very small particles that can be easily inhaled. They can also penetrate very deep into your respiratory system.”
This isn’t just a win for air quality. The study influenced Governor Gavin Newsom’s approval in November 2025 of legislation allowing the sale of E15 at California fueling stations. For drivers, the change could mean savings of up to 20 cents per gallon at the pump, according to a separate study by UC Berkeley and the U.S. Naval Academy. Since ethanol is typically made from domestically grown corn and soybeans, it’s less expensive than gasoline derived from crude oil, providing a rare bit of relief for motorists facing stubbornly high prices.
The UC Riverside team took a rigorous approach, assembling a fleet of 20 passenger cars and light-duty trucks representative of California’s diverse on-road vehicles. They sourced gasoline samples from three Southern California refineries and one in the Bay Area, blending them to mimic the fuel actually used across the state. The vehicles were then put through their paces on a chassis dynamometer, using federal testing protocols to ensure the results would stand up to regulatory scrutiny.
Interestingly, while nitrogen oxides (NOx)—a key ingredient in smog—showed no significant change between E10 and E15, the reductions in other pollutants were clear. This has important implications for California’s so-called ethanol blend wall, a regulatory cap that has limited ethanol in gasoline to 10% due to fears about worsening air pollution in already-vulnerable regions like the South Coast Air Basin and the San Joaquin Valley.
But the new evidence may help regulators reconsider. “Higher ethanol blends, as well as other low-carbon and zero-carbon biofuels, must be part of the mix for a sustainable and clean transport sector that will coexist with other proven clean technologies, such as battery electric vehicles,” Karavalakis said. He added that the benefits extend beyond consumers to American farmers, who will see increased demand for their crops, and to national energy security, since ethanol is a renewable, domestically produced fuel.
From a climate perspective, ethanol’s appeal lies in its lower carbon footprint. Made from corn or cellulosic biomass, ethanol’s combustion releases carbon dioxide that was originally absorbed from the atmosphere during plant growth—essentially recycling the carbon, rather than adding new fossil-based emissions.
California’s move is part of a broader U.S. trend. The Environmental Protection Agency already allows E15 for use in all vehicles from 2001 onward, and the blend is available in 31 states at more than 3,000 gas stations. The UC Riverside study could provide the data California regulators need to support wider E15 adoption, helping the state meet its ambitious clean air goals.
Meanwhile, on the other side of the globe, India faces a very different set of biofuel challenges. As reported by Policy Circle on November 26, 2025, the country is debating whether to push its ethanol blend beyond the current 20% threshold. But unlike California, India’s primary concern isn’t just air quality—it’s the intersection of energy security, rural livelihoods, and environmental sustainability.
India can’t simply copy the global playbook. Brazil, for example, is often held up as the gold standard for ethanol production, thanks to its rain-fed sugarcane fields that yield about 6,500 liters of ethanol per hectare. But Brazil’s model is deeply water-intensive, consuming about 2,800 liters of water for every liter of ethanol produced. With India’s per capita water availability having dropped by more than 70% since independence, and arable land at a premium, scaling up first-generation (1G) biofuels from sugarcane or corn just isn’t sustainable.
Instead, India is looking to its massive supply of agricultural residues—over 750 million tonnes annually, according to NITI Aayog. These include paddy straw, sugarcane bagasse, and cotton stalks, which could yield about 42 billion liters of ethanol-equivalent each year without diverting land from food production. Second-generation (2G) biorefineries, which convert these residues into fuel, also produce valuable co-products like lignin, biogas, and fertilizer blends, supporting rural incomes and reducing the scourge of stubble burning.
Yet, the economics are daunting. Producing 2G ethanol in India currently costs between ₹85 and ₹110 per liter—much higher than 1G biofuels. Private investment has been slow, hampered by the lack of long-term purchase agreements, viability gap funding, and the logistical challenge of aggregating, storing, and transporting bulky, seasonal residues. These hurdles are familiar worldwide; several 2G projects in the U.S. and Europe have shuttered after running into unexpectedly high enzyme costs and inconsistent feedstock supplies.
Despite these obstacles, experts argue that India’s residue-based strategy offers superior environmental benefits. Unlike 1G biofuels, which can trigger indirect land-use changes (and thus offset their carbon savings), residue-based fuels avoid these penalties, require far less water, and help preserve biodiversity. “India’s residue-based model delivers a more balanced environmental return per hectare, even if ethanol yields are lower,” wrote Dr. Akanksha Jain and Dr. Debajit Palit for Policy Circle.
Biofuels also offer a powerful economic multiplier, especially in rural areas. Studies show that biofuels can generate up to 100 times more rural employment per megawatt equivalent than solar energy. When factoring in co-products and avoided pollution costs, the broader benefits become even clearer.
Looking ahead, India’s experts say the country should channel biofuels into hard-to-electrify sectors like aviation, long-haul trucking, shipping, and inland waterways, rather than passenger cars. Success will depend on building the right investment conditions: predictable pricing, long-term purchase commitments, robust biomass supply chains, and financing for integrated biorefinery clusters. As a leader in the Global Biofuel Alliance, India is also pushing for international standards on sustainability certification and financial frameworks to make residue-based biorefineries viable at scale.
The stories of California and India reveal that there’s no one-size-fits-all solution to the world’s biofuel puzzle. Local context—be it air quality, water scarcity, or rural livelihoods—matters. But if there’s a common thread, it’s that biofuels, when crafted to fit regional realities, can be a powerful tool for cleaner air, stronger rural economies, and a more sustainable energy future.
