The Sustainable Aviation Fuel Grand Challenge Roadmap recognizes the importance of the aviation industry and its impact on the overall economy. Decarbonizing this transportation system segment is critical to support the continued growth of the aviation industry and economy. Among many goals set in the roadmap is the U.S. aviation industry reaching net zero carbon by 2050. While light-duty cars and trucks are making a slow transition to electric power, there is no easy electrification option for the aviation sector, which is why deploying new SAF technologies is critical.The roadmap lists various renewable feedstocks that could be used to make SAF, including biomass sources such as fats, oils and greases (FOG), algae oil and wet waste. Estimated volumes of renewable fuel that can be produced by established technology pathways include: 48.8 billion gallons per year (BGY) from biomass and municipal solid waste; 1.85 BGY from FOG; 3.28 BGY from wet waste; and 24 BGY from algae oil. Thus, the total resource base provided in the roadmap can generate about 78 BGY. These projected yields are conservative with respect to the conversion technology, but it is aggressive to assume 100% of potential feedstocks can be gathered and processed. According to the U.S. EIA, projected U.S. transportation fuel demand in 2050 is about 183 BGY.&nbsp;To date, projects have been difficult to scale due to distribution of feedstocks. &nbsp;Proposed plants using biomass or MSW tend to be in the 15 million gallons per year (MMgy) to 75 MMgy range. The projects based on FOG have the potential for larger scale, as the feedstock is more easily gathered and transported to a central plant. However, this option is very limited.&nbsp;Soy oil is an example of an SAF Grand Challenge Roadmap feedstock, but it and other FOGs only account for a portion of 1.85 BGY. Soy oil is extracted from the soy plant leaving meal, which has a market, as does the oil. Farmland is used to plant major crops like soybeans, and the products are used in food markets. Shifting production to increase soy oil for fuel production could disrupt or imbalance food markets, and this tends to limit growth for this feedstock.Biomass and MSW are more complicated feedstocks to utilize. Once gasified to make synthesis gas, they can be converted into liquid hydrocarbons via Fischer Tropsch (FT) synthesis and further refined into jet and diesel fuel products. Biomass from forest products or crop waste are not as sensitive to the food vs. fuel balance, but they still must be managed. &nbsp;They also have a cost to generate, gather and deliver to a plant. Transportation costs limit the practical size of biomass to renewable fuels projects. Small, distributed projects located near a particular feedstock will be the norm for most plants. Assuming an average size of 35 MMgy, utilizing the total biomass resource base of 48.8 BGY will require about 1,400 biofuel plants. While there is enough fuel potential from this resource base to completely decarbonize the aviation sector, this is only enough fuel for about 27% of our total transportation fuel needs. Based on biomass-to-liquids projects that have been built, an average capital cost of about $350,000 per barrel of daily capacity requires investments nearing $1.2 trillion to transition just 27% of our hydrocarbon products to renewable sources.In recent years, there has been growing interest in capturing CO2 from ethanol plants, smokestacks or directly from the air or seawater, to split to yield carbon monoxide (CO) and oxygen. Water can be split by electrolysis to make hydrogen. Hydrogen and CO (synthesis gas) are the building blocks for FT hydrocarbon products. This pathway represents a virtually unlimited method to recycle fuel products, making them carbon neutral, but it requires a lot of carbon-free energy. With this option, we have no limits on decarbonization. What can be directly electrified will be; the rest can be indirectly electrified with efuels. &nbsp;As a reference point, consider this: &nbsp;Our current electric grid generation capacity is about 1.1 million megawatt-hours (MWh). &nbsp;It must grow to 1.9 million MWh by 2050 to accommodate the anticipated electric vehicles and market growth, and at least an additional 1.1 million MWh to make the liquid transportation fuels needed to completely decarbonize the U.S. &nbsp;And it is only truly decarbonized if the electricity comes from carbon-free sources.These carbon-neutral fuels will require trillions of dollars in capital investments, resulting in a much higher price than we have been accustomed to paying. Therefore, government incentives in the form of penalties or taxes for not adopting them, or in the form of credits and direct payments to producers, will be required to enable production and growth of these fuels.The level of commitment from industry and government alike to transition from fossil fuels to electricity or carbon-neutral fuels has grown substantially in recent years. This effort to decarbonize may be led by the aviation industry, but will not stop until all segments are substantially converted.Author: Kenneth Agee&nbsp;&nbsp; Founder and President,&nbsp; Emerging Fuels Technology

The Hurdles of SAF

Upcoming Events

2024 International Fuel Ethanol Workshop & Expo

Biodiesel Summit: Sustainable Aviation Fuel & Renewable Diesel

Carbon Capture & Storage Summit

North American SAF Conference & Expo

2025 International Biomass Conference & Expo

The Hurdles of SAF .css-7jxktu{position:absolute;bottom:0px;left:0px;right:0px;height:3px;border-radius:3px;background-color:var(--chakra-colors-brandBlack);}

Upcoming Events

2024 International Fuel Ethanol Workshop & Expo

Biodiesel Summit: Sustainable Aviation Fuel & Renewable Diesel

Carbon Capture & Storage Summit

North American SAF Conference & Expo

2025 International Biomass Conference & Expo

The Hurdles of SAF