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Advanced Fuels

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  • Welcome! Willkommen!

    You´ll get all important information to start the learning arrangement advanced fuels here!

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      Welcome!

      This learning material gives an overview of the production processes of different types of fuel that are already available or will play a greater role in the substitution of petroleum-based fuels in the future. Information is also provided on the feedstocks for advanced fuels.

    • This learning material gives an overview of the production processes of different types of fuel that are already available or will play a greater role in the substitution of petroleum-based fuels in the future. Information is also provided on the feedstocks for advanced fuels.
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    • Definition Advanced Fuels

      An advanced fuel is one considered to be capable of curbing greenhouse gas emissions by at least 50% as compared to crude oil based fuels (Lima & Bacchi, 2018). Most of the today already produced advanced fuels are based on biomass resources and are called biofuels. In the future, synthetic fuels based on abiotic renewable energy sources (e.g. renewable electricity) will gain greater importance.

      Biofuels:
      In 2018 154 billion liter of biofuels were produced worldwide (IEA, 2019). Large amounts of currently used biofuels are derived from vegetable oils. Bioethanol is the most widely used biofuel worldwide. 28.4 billion gallons have been produced worldwide in 2019, which are approximately 107.5 billion liter. 57% of this amount was produced in the USA (60.9 billion liter) and 28% in Brazil (30,2 billion liter). The European Union produced as much as 5.4 billion liter which are 5% of the total volume (Renewable Fuels Association 2020).

      The world production of biodiesel from vegetable oil is much lower. Around 5.5 billion liter were produced on 2018. Advanced biofuel output, i.e. produced from non-food feedstocks, was 13.5 billion liter. Mostly waste fats, oils and grease were used for that. Novel advanced biofuel production from municipal solid waste or forestry and agriculture residues amounted to 1.4 billion l in 2018 (IEA 2019).

      There are many different methods of biofuel production available. Some are already tested and in use, others are still at an experimental stage or in the trial phase. Therefore biofuels can be grouped into 3 types, also known as generations. The characterization is related to the feedstocks used and the state of their technological development:

      1st generation fuels:
      • Conventional biofuels
      • Based on sugar, starch or vegatable oil, i.e biomass that is also used as food 
      • Processing technology is well understood and already widely used and commercialized

      2nd generation fuels:
      • Based on non-food cellulosic biomass (like straw or corn stover) but still demand land resources that compete to food production because they have similar requirements to soil, water, light and nutrient supply 
      • Mostly they have higher energy yields per hectar
      • Processing technology is partly immature and costly because cellulosic material has to be pre-treated before conversion

      3rd generation fuels
      • Use special microorganisms like algea
      • Algea are a large group of photosynthesizing organisms with approximately 30 000 known species (Aziz et al. 2019)
      • Small-scale algea biofuel production is well-established but the industrial scale is not yet economically feasible
      Whole book about §rd generation biofuels:
      Baijpai, Patima (2019). Third Generation Biofuels. Springer Singapore.
      https://doi.org/10.1007/978-981-13-2378-2

      Meanwhile also a 4th generation of fuels is being identified. Herewith biofuels produced via genetically engineered algea (or other crops) are considered. Genetical modification can overcome the constraints of "normal" crops, i.e. low lipid contents or low groth rates.
      In some cases also biohydrogen, biomethan, synthetic biofuels and electro fuels or solar-based fuels, sometimes in combination with carbon capture and storage, are considered as 4th generation fuels.

      An overview of the maturity of various biofuel production processes you can also find in the following publication at page 5:
      Ebadian et al (2020). Overview of the maturity of biofuel production processes.
      https://www.ieabioenergy.com/wp-content/uploads/2020/11/Production-Technologies-and-Costs.pdf

      Synthetic fuels:
      A characteristic of synthetic fuels is that they are synthezied (e.g. via Fischer-Tropsch-Sysntheses) from other resources than crude oil, which is usally cracked into its fractions by destillation or rectification. Resources can be biomass (BtL - biomass-to-liquid) but also natural gas (gas-to-liquid) or coal (coal-to-liquid). But also further fuels can be derived from synthesis gas, e.g. methanol, dimethyl ether, synthetic natural gas or hydrogen. Therefore the term "synthetic fuels" is somtimes used synonymously to electrofuels (e-fuels).

      Electrofuels and solar-based fuels:
      For electrofuel production electrical energy, preferably from renewable sources, is converted into chemical energy in liquids or gases with the help of water and carbondioxide (CO2). The products are e.g. gases like hydrogen, methane or butane or liquids like dimethyl ether (DME), ammonia, butanol or methanol.

      Issues and fuel types covered by this material  

      • Feedstocks for bio-based fuels
      • Conversion routes for 1st and 2nd generation biofuels
      • Electrofuels

  • 1. Feedstocks for biofuel production

    Feedstocks for biofuel production encompass crops, agricultural residues, and waste materials utilized to produce renewable biofuels. Crop-based feedstocks like corn and soybeans, along with agricultural residues such as corn stover, are commonly used. Waste materials like used cooking oil and forestry residues also serve as valuable feedstocks. In this section you learn about different types of Feedstocks.


    • Different feedstocks from agiculture and forestry are available as renewable raw materials for biofuel production. Since the varoius materials have different chemical properties, they require different types of conversion processes. Many of the materials discussed below are primarily used in food production. Therefore, the actual availability appears to be high, but after taking into account other uses, the actual remaining potential is much lower. We therefore distinguish between different types of the term “potential” (definition according to Roth et al. 2018).

      The geographical potential reflects the physical and biological limits of plant growth, i.e. land, water, solar radiation and nutrient availability.

      The technical potential is lower than the geographical potential and takes technical issues like conversion efficiencies and other exisiting technical, infrastuctural or legal restrictions for cultivation, harvest, transport and conversion of biomass into consideration.

      The economic potential not everything which is technically feasible is also economically viable. Therefore the economic potential can only be a part of the technical potential.

      If not already considered in the other categories, the sustainable potential also takes social and environmental restrictions into account. For example nature reserves, territorries of indigenous peoples, recreational areas and land required for the cultivation of food and feed cannot easily be used for expanding feedstock production for biofuels.

      Results of studies examining biomass potentials for biofuel production vary greatly if they are based on a different understanding of the term "potential".

      For further information see the chapter of Roth et al. (2018) for an estimation of potentially available biomass resources for biofuel production.

      Read a detailed review of the current knowledge of factors influencing the competion of biomass use for food, feed and bioenergy (Muscat et al. 2020) by following the link:

      Muscat, A. et al (2020). The battle for biomass: A systematic review of food-feed-fuel competition. Elsevier.
      https://doi.org/10.1016/j.gfs.2019.100330

      Current fuel demand and supply from bio-based resources
      Almost 378 EJ of final energy were consumed worldwide in 2018. Only around 11% of this demand was supplied by bioenergy (IEA 2020). The biggest proportion of bioenergy is used for cooking and heating. 
      Globally 121 EJ of energy were consumed in the transport sector in 2018 (IEA 2020). Only around 3% of this demand was supplied by biofuels (IEA 2019), i.e. 3.6 EJ of bioenergy were used in the transport sector as liquid fuels. The biggest proportion (62%) of these biofuels was produced from sugar or starch rich crops (bioethanol).
      A forcast of the International Energy Agency pojects a 24% increase of biofuel output until 2024 (IEA 2019). The biggest increase in growth is forcasted for biodiesel and vegetable oil based fuel (e.g. HVO). Hydrotreated vegetable oil (HVO) is mostly based on waste fats, oils and grease. Novel advanced fuels, based on non-food crops like municipal solid waste, forestry or agriculture residues currently have a low market share (1.4% of all biofuels in 2018) but their use is expected to double by 2024.

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      1.1 Sugar and starch rich crops Book

      The book "Sugar and Starch Rich Crops" focuses on crops with high sugar and starch content.

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      1.2 Vegetable oils and animal fats Book

      In this book you get to know different types of oils from plants and animal fats.

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      1.3 Lignocellulosic biomass Book

       This book highlights lignocellulosic plants, characterized by their woody tissue composed of cellulose, hemicellulose, and lignin.


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      1.4 Alternative feedstocks Book

      This book presents algae and wastestreams from housholds or industry like municipal solid waste, landfill gases or sludge from wastewater treatment. 

  • 2. Biofuel production pathways

    This section describes the most important process pathways for converting the biomass feedstocks described above into biofuels.

    • Depending on their chemical composition, different processing technologies are required. Various types of fuel can be produced from the different components of biomass feedstocks (i.e. carbonhydrates or lipides). The following figure provides an overview of the different ways of obtaining biofuel from biobased feedstocks.

      

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      2.1 Bioethanol (sugar or starch-based biofuel) Book

      In this book you´ll read about the sugar, starch, and nowadays also lignocellulosic-based biofuel ethanol.

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      2.2 Biodiesel (oil and fat-based biofuel) Book

      The book on biodiesel provides a comprehensive overview of this renewable fuel source.

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      2.3 Lignocellulosic-based biofuels from synthesis gas Book

      The book on Lignocellulosic-based biofuels from synthesis gas explores the conversion of lignocellulosic biomass into biofuels.

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      2.4 Algal or waste-based fuels Book
      Fuels from algae or organic waste can be produced with similar processing routes. Therefore they will be discussed together in this book.

  • 3. Electrofuels

    Electrofuels are a type of synthetic fuel produced by using renewable electricity to power the conversion of carbon dioxide (CO2) and water into liquid or gaseous fuels. This process, known as electrochemical or power-to-fuel conversion, has the potential to offer carbon-neutral alternatives to traditional fossil fuels and help decarbonize the transportation sector. In this section you learn about different types of electrofuels.

    • Electrofuels are advanced fuels based on electric current. The term is therefore more referring to their production process than to the fuel itself. The processing is always based on hydrogen that is obtained from the electrolysis of water. The hydrogen can then be converted into gaseous or liquid fuels using many different processes (see the following figure).

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      Technologies for electrofuel production are existing but mostly they are still in the demonstration phase. Therefore production costs of electrofuels are very high, but they are expected to decrease when technology is transferred to a larger scale, if electricity costs are decreasing and the conversion efficiency increases.
      The big advantage of electrofuels compared to direct use of electricity (e.g. in electric vehicles) is their easy integration into the already existing fuel supply and usage infrastructures. This means, they can used as drop-in fuels like petroleum-based fuels - no additional logistic chains or petrol station infrastructure have to be established. Additionally, the production of hydrogen and electrofuels allows to store fluctuating supply of renewable energy from wind or sun. The main point is that electrofuels are suitable to fuel heavy-duty vehicles like ships, trucks or airplanes, which cannot be operated by battery-powered engines so far.
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      3.1 Hydrogen from renewable sources Book

      The book Hydrogen from Renewable Sources explores the production of hydrogen.

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      3.2 Power-based methane and methanol Page

      Here you get some further infomation about Power-based methane and methanol.
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      3.3 Power-to-liquid (PtL) Book
      In this book you learn about the synthetic fuels Ptl and their production process.

  • Wrap up

    You'll find out what you've learned, see the list of references and give feedback in this section. You can also download your Certificate of Participation in English or German.

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      Congratulations!

      You have arrived at the end of the learning offer and thus end your journey in this topic.

      Great that you made it this far! I hope you were able to take a lot of exciting new information with you from this learning opportunity, broaden your horizons and learn something new.

      At the same time, of course, I also hope that you had fun dealing with the content.

    • You learned...

      ... to explain the production processes of various fuel types

      ... to know which fuel types are already available or which will play a greater role in the substitution of crude oil-based fuels in the future

      ... to know about the feedstocks of advanced fuels


      ... zu wissen, welche Kraftstoffarten bereits verfügbar sind oder in Zukunft eine größere Rolle bei der Substitution von erdölbasierten Kraftstoffen spielen werden

      ... zu wissen, welche Rohstoffe für fortschrittliche Kraftstoffe verwendet werden

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      List of References Page