After every harvest season, U.S. corn fields lay strewn with husks, leaves and stalks — waste left behind after corn kernels are collected. Some farmers feed these leftovers, known as ‘stover,’ to animals, or use it as a natural fertilizer. But much of it goes underutilized.New WRI research shows that this corn stover could be put to better use by helping reduce emissions in one of the most difficult sectors to decarbonize — aviation. The Future of Sustainable Aviation Fuel in the Midwestern United States Finding: Alternatives to Crop-Based BiofuelsView FindingMaking Jet Fuel from Corn Stover Can Meet Growing Demand without Contributing to Climate ChangeThe price of conventional jet fuel made from crude oil recently doubled after the war on Iran closed the Strait of Hormuz, tightening global supplies. But the race to develop alternatives to petroleum jet fuel predates the war for a different reason: the need to clean up the industry’s pollution. The aviation industry already accounts for 2.4% of the world’s greenhouse gas emissions, a figure projected to triple by 2050 as demand for air travel grows. Aviation is one of the hardest sectors to decarbonize. Unlike in electric vehicles, batteries are currently too heavy to work for most flights. The world will need clean alternative fuels, alongside increases in aircraft efficiency, operational improvements and, ultimately, new propulsion technologies to make flying more climate-friendly.Some governments have responded with measures such as the U.S. Sustainable Aviation Fuel (SAF) tax credit and the EU’s SAF mandate. But not all alternative jet fuels are actually sustainable. Growing conventional bioenergy crops, such as corn and soy, to produce fuel could divert millions of acres of prime farmland away from food production while only supplying a small share of jet fuel demand. Doing so would not only hike up food prices, it would drive deforestation in other parts of the world to satisfy the demand for food. In other words, some ‘sustainable’ aviation fuels will actually produce more emissions over their entire lifecycle than traditional fossil-based jet fuel!Our research finds corn stover to be a better alternative — for both people and the planet.An estimated 90 million tons of corn stover is available every year after accounting for the fraction that should be left on fields to maintain soil health. This is more than enough to produce 3 billion gallons of truly sustainable fuel, an amount that would meet short-term U.S. SAF targets and satisfy about 10% of U.S. jet fuel demand.Making jet fuel from corn stover is a win-win: It turns underutilized waste into an energy resource without expanding our agricultural footprint. Moreover, using stover can reduce airplane emissions by 75% or more compared to planes powered by fossil fuel. This is in sharp contrast to converting vegetable oil or corn ethanol into jet fuel, the primary approaches currently being pursued in the United States. Corn Stover Fuels Could Create Jobs and Other Economic BenefitsAnd it’s not just the climate that would benefit. A corn stover SAF industry could support jobs in the U.S. Midwest, a region also known as the Corn Belt, at a time when rural areas of the U.S. are experiencing lagging incomes and job growth. Moreover, it could help struggling farmers by providing another income source. According to our research, investing in 3 billion gallons of corn stover SAF production per year could support as many as 99,000–214,000 jobs. This includes jobs for constructing and operating new SAF facilities, jobs that are indirectly connected to SAF production up and down the supply chains (such as manufacturing jobs to build equipment used in SAF facilities), and service jobs like restaurant workers, which are generally supported by more economic activity. (These numbers don’t account for the possibility that investing in SAF could shift some jobs away from other industries.) This number of jobs would support $7 billion-$15 billion in labor income and contribute $9 billion-$32 billion to the region’s GDP, which is used as a general indicator of economic health. Additionally, this level of economic activity would support $4 billion-$10 billion in tax revenue for the region. The potential contribution from a 3-billion-gallon-per-year corn stover SAF industry to the Midwestern economy is comparable to that of corn ethanol, an industry with great support. But importantly, it would come without the negative impacts on the climate and food production. However, these economic impacts will only be possible with a concerted effort to invest in new technologies. WRI research estimates that the capital investment needed to make a 3-billion-gallon-per-year industry a possibility ranges from $39 billion-$131 billion.This is because the technologies for turning corn stover into jet fuel are nascent and not yet cost-competitive with conventional jet fuels. But the gap is narrowing as traditional fuel prices spike from geopolitical conflicts like the war on Iran, making new forms of SAF more attractive to investors and airlines alike.How to Make Corn Stover Fuels a Reality Corn stover’s potential to reduce emissions and support the regional economy won’t be realized without policy support for research and development as well as deployment incentives.Research is already underway to determine the best technology options for harnessing corn stover in aviation. Some technologies are more developed, like alcohol-to-jet facilities that can take advantage of existing ethanol industry infrastructure. Fischer-Tropsch synthesis can more efficiently convert stover into jet fuel. Other technologies, like power-to-liquid or power- and biomass-to-liquid, have more potential to scale and become cost-effective, but need significant research and development to mature. Another option doesn’t entail converting waste into jet fuel, but would instead compensate for aviation emissions via corn stover carbon dioxide removal (CDR).Our research shows that there is no silver bullet technology. Rather, policy should support research and development of a diverse portfolio to understand which technologies have the most potential.Governments can also help channel more investment into corn stover fuels to help reduce costs as the industry scales, all the while creating a more stable fuel supply for airlines. The U.S. could, for example, mandate that airlines purchase low-carbon SAF or CDR. Regardless of the type of policy, support should be limited to only those SAF pathways that take advantage of wastes like corn stover or use e-fuels made using additional renewable energy, to ensure true sustainability. Securing a Better Jet Fuel Airlines need to find alternatives to petroleum and cut their emissions. Turning waste into fuel is a great way to start. Corn stover is the U.S.’s most abundant agricultural waste. A stover-based SAF industry can help contribute to our energy security, reduce aviation emissions, and support the economy of the Corn Belt.