RFNBO

Renewable fuels of non-biological origin (RFNBO), term introduced by the EU Renewable Energy Directive 2018/2001 (RED II), are a category of fuels produced from hydrogen derived from renewable energy (except biomass sources) in the form of heat or electricity, and CO2 deriving from flue gases or from direct air capture (DAC) techs, or N2 captured from the air [EC, 2022].

  

H2 with CO2 or N2

  

Since CO2 and N2 are not energy carriers, all energy transferred into such carbon- or nitrogen-based fuels derive from hydrogen [EC, 2023].  Fuels that may be produced by combining H2 and CO2 or N2 are hydrocarbons, alcohols, and ammonia.  Together w/ advanced (or 2nd gen) biofuels, RFNBO consist in a ready alternative to fossil liquids fuels for the market, being fully drop-in.

  

Within the category of RFNBO, in addition to pure hydrogen, derived from water and renewable energy (except biomass sources in the form of heat or electricity, there are i) e-fuels (H2 plus CO or CO2), ii) solar-derived fuels (when H2 uses the sunlight as energy source to split hydrogen from water), iii) other fuels derived from renewable heat, and iv) fuels from microbes thru synthetic biology, cyanobacteria or chemical catalysis.

  

Indeed, RFNBO may designate renewable hydrogen itself but also its derivatives, i.e., advanced fuels based on renewable hydrogen.  One of the main techs to produce RFNBO is electrolysis powered by renewable electricity to produce H2 [TE, 2023].

 

Food security

  

Since food security, according to UN FAO (Food and Agriculture Organization), has multiple dimensions, such as availability, accessibility, stability, and utilization, the production of the renewable fuels of non-biological origin contributes to enhanced economic conditions of rural communities, new job opportunities, increasing overall food availability, food accessibility & affordability [FAO, 2020].

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Certification

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Renewable hydrogen deriving from renewable electricity needs harmonized, coherent, and consistent certification schemes which deliver guarantee of origin (GoO) that can be recognized and used at a global level.  Such certification schemes could allow us to use a single methodology to calculate the GHG emissions and life cycle assessment (LCA) of hydrogen [EC, 2022].

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Viability

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The production of RFNBO will depend on the availability of surplus renewable electricity and its price.  The availability of economical CO2 (concentrated in flue gases, or from industrial process, or from DAC) or N2, as well as the green hydrogen supply, are crucial to reduce the production costs.  RFNBO conversion pathways are at early TRLs, and still need tech improvements, demonstration, de-risking, and commercial validation in the future.

  

Automotive industry promote e-fuels as an alternative solution to the phasing out of the ICE (internal combustion engine) for cars & trucks.  But there are opposing views due to its poor efficiency & high-cost for drivers & manufacturers.  First incentives are targeting aviation & maritime transport sectors [TE, 2023].