CleanJoule has begun the process of having its CycloSAF sustainable aviation fuel (SAF) meet ASTM International’s D4054 standard for blending with jet-A/A1 fuel. The Utah-based company, which announced the move this week, is aiming to start production of what it said will be a 100% drop-in fuel for aircraft in 2026.
According to CleanJoule, its synthetic blending component will deliver 10% greater energy density than jet-A and is made from a feedstock of waste biomass. Its process is based on increasing the proportion of cycloalkane hydrogen molecules in its SAF to eliminate the aromatics that cause contrails and boost energy density.
After establishing an industrial demonstration plant in 2026, CleanJoule aims to scale up the output of its SAF between 2029 and 2030. It plans to establish plants in multiple locations worldwide, including the U.S., Brazil, India, and Thailand.
Biomass waste sources will include corn residue left behind on farms once the wheat is harvested. According to the Billion Ton Report on renewable carbon resources published by the U.S. Department of Energy in March 2024, about 1.3 tonnes of biomass are available each year and are not being harvested.
The Promise of 100% Drop-in Fuel
To date, eight production processes are compliant with ASTM's D7566-22 specification for aviation fuel containing synthesized hydrocarbons. According to CleanJoule founder and CEO Mukund Karanjikar, CycloSAF is currently the air transport sector’s only option for a 100% drop-in fuel and represents a near-term path for SAF use to cut the industry’s carbon emissions by 65% as it strives to meet its net-zero target in 2050.
Both the U.S. Departments of Energy and Defense have provided funding for CleanJoule’s work as part of efforts to establish options for decarbonization that also avoid price volatility, foreign energy dependency, and supply chain risks. The company’s investors include Frontier Airlines, Wizz Airlines, and Volaris.
Karanjikar told AIN that currently approved SAF processes are limited to blends of 50% and that delivering a 100% drop-in fuel will be a force multiplier scaling up the reduction of carbon from flights. “For density, meaning how much the fuel weighs per unit volume, the current [ASTM] requirement is between 0.775 and 0.84 kilograms per liter,” he explained. “Currently 'approved' SAF is 0.75, and we are focused on achieving 0.81 to 0.84.”
Blending is a technical requirement of the majority of SAFs today. According to CleanJoule, it is possible to produce SAF that exceeds the current requirements and has the energy density properties to be a 100% drop-in replacement for jet-A. Until regulations permit this approach, the company needs to get CycloSAF approved as a blended fuel.