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June 27, 2023

eJet potential is big but it needs more renewable energy & CO2 sources

If we want eJet fuel to step into the SAF conversation big time as a productive pathway -and we do - what needs to happen and what do producers need to consider? asks Sandra Winter-Madsen, Product Line Director at Topsoe. 

eJet fuel is considered to be one of the Sustainable Aviation Fuel (SAF) pathways with the most long-term potential. It is produced using renewable electricity to produce hydrogen from water, with the hydrogen then combined with carbon dioxide (CO2). This CO2 can be from different sources with the most sustainable from the atmosphere via Direct Air Capture (DAC) or via biogenic CO2, which comes from biological sources such as biogenic waste incinerators, ethanol plants or biogas production plants.

As eFuel production methods use biogenic or DAC CO2 and employs renewable, zero-emission energy (as a feedstock and in production), it means eJet can be produced with close to zero GHG emissions. In the short term, however, the industry must overcome a renewable energy resource squeeze and CO2 scarcity from sustainable sources (for instance, DAC has still to reach full commercialization). 

However, with supply limitations on biomass feedstock constricting the amount of SAF that can be produced this way in the long term, the SAF industry must diversify the types of feedstocks and pathways to upscale production and ultimately decarbonize the aviation sector. eJet will be key to this.

We need to increase the capacity for renewable energy

Renewable energy and sustainable CO2 availability are critical for eJet fuel production. The production of eJet fuel is energy intensive and needs a significant amount of renewable power and while wind, solar, hydro, waves, and tidal energy are environmentally friendly, they are not yet readily available in large enough quantities. There is also a lot of demand for their output from other industries and uses which makes it competitive to secure a reliable and affordable supply of renewable power, even as supply increases.

Renewable energy sources can also be intermittent, meaning that the eFuels production process needs to adapt to these intermittencies. With no grid connection, this may require energy storage capacity or a backup source of energy to ensure consistent and reliable production. 
So yes, there are challenges, but already today significant infrastructure investments are in the pipeline, while renewable energy production only continues to grow. Meanwhile, if an energy source is grid-connected, it may provide stable source of power for eFuels production. However, specific legislation may need to be followed in this case, so many producers plan to operate "island" plants, and many renewable sources of power may never be grid-connected. 

Alternatives are also under development with a focus on overcoming intermittency issues. These include improvements in renewable energy configurations, H2 geological storage and buffering. 

Optimizing and maturing CO2 sources

There are four main CO2 sources that can be employed to produce eFuels. Their feasibility depends variously on factors such as scalability, technological maturity, costs, supply, and legislation. The four sources are: Unavoidable CO2 from flue gas released by industries such as cement plants; captured CO2 from flue gases in refineries; Biogenic CO2, which is carbon dioxide derived from biological sources such as biogenic waste incinerators; and Direct Air Capture (DAC), which captures CO2 directly from the air.  

For producers and would-be producers, regulation, incentives and cost, local availability of CO2 sources, and the concentration and purity of the source need to be considered in detail. eFuels regulation is likely to be a fast-changing landscape over the coming years so producers also need to be aware of alterations during the energy transition to securely de-risk and future-proof production. For eJet/eSAF, most of the projects will be based on biogenic sources, and in the future on DAC.

Ramping up electrolyzer capacity 

Electrolyzers are essential equipment in the production of eFuels because they are used to split water molecules into hydrogen and oxygen using electricity from renewable energy sources. The electrolyzer market is experiencing a supply squeeze worldwide due to the rapid growth of the green hydrogen industry and the increasing demand for electrolyzers.  

The positive development is that manufacturers have begun to ramp up their production capacity based on the expectation of future demand growth. The ramping up of both electrolyzer and renewable energy capacity are ensuring more green H2 molecules and also driving down the cost down for green H2. This is critical for eJet/eSAF operating costs, as a significant part of the cost is from green H2. 

The journey ahead for eJet

Key to eJet fuel production is to secure an increased and economically attractive supply of renewable energy. The “island” approach favored by some producers means a more predictable supply of renewable energy, while location, infrastructure maturity and local policy support are key factors to be considered. In an energy grid scenario, reliable agreements between suppliers and for a predictable supply of renewable energy will be necessary, as well as transparency around energy production. 

The other eFuel feedstocks, water and CO2, also need to be considered through the lens of local availability, though for CO2, the development and commercialization of DAC will in the future provide a sustainable and reliable CO2 source. It is worth noting, energy and carbon management will be crucial to reducing costs. Innovative and integrated technologies that utilize waste heat from one process unit and reuse it in another can deliver high utilization of energy and feedstocks.

Finally, it is critical that governments provide financial and regulatory support to encourage investment and innovation in eJet fuel production, especially in areas such as renewable energy, CO2 sourcing and electrolyzer capacity scale up. This includes tax incentives, subsidies, mandates. All industry parties across the value chain need to work together to accelerate production and bring eJet fuel to the market as soon as possible. 

This blog was based on one of the eight challenges facing the SAF industry identified by industry experts in the Voices from the Sky report. Click here to read the report >> 

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