There are two types of raw materials that can be used to produce biofuels.
One possibility is to use recycled material and organic waste. The other option is the cultivation of plants to produce first and second generation biofuels.
1. The feedstock always determines which biofuel technology can be used.
First, before deciding which biofuel technology to use, we need to determine which feedstock to use. Secondly, we must determine what can be considered a biofuel. It is perhaps best to categorize biofuels by their end use, which is what we use them for. If we use biofuels for transport, for diesel engines, then 1) agricultural crops and 2) waste fractions from recycling plants can both qualify as biofuels.
The only exception is that recycled waste produced from petroleum products, such as plastic waste fractions. This means that plastic waste fractions are not naturally carbon neutral. If we define biofuels by their carbon neutrality, then plastic waste fractions cannot be considered biofuels. Ultimately, it depends on the feedstock. Once we find the feedstock, we can determine which biofuel technology we want to use, for example pyrolysis, gasification or a more advanced plasma technology to produce the fuel.
2. Current developments
The biofuel industry has made considerable progress in recent years and has reached a higher level of development. We are now making progress in the development of second-generation biofuels and are trying to bring production to a level where they can compete with fossil fuels. Algae biofuels have probably been the most interesting area in terms of technical development alongside plastics-to-fuel research, which has also made considerable progress.
One of the most important developments is the cultivation and growth of algae for biofuel production. The key to the development of biofuels is to increase the calorific value of the algae that are processed into biofuel. Another important development is the processing of lignin for the production of biofuels, which accounts for a significant proportion of wood residues. Innovation usually results from a need that must be satisfied. Another requirement is that there must be substances from which something new can be produced. This is linked to the idea that modern society wastes a lot of material.
As far as waste for the production of biofuels is concerned, we have two types of input materials. The first is recycled material and organic waste collected from households. In this case we already have material that has a high energy density and is ready to be used for the production of biofuels. On the other hand, we can produce first and second generation biofuels. This means that we have to cultivate the plants first. In this case, we consume a lot of water resources and use the land to produce biofuels instead of using it for agricultural production.
3. What technological options are currently available for the production of biofuels?
Pyrolysis and gasification technology for biofuels can be used in combination to produce a higher quality fuel. This is particularly relevant when converting recycled material and organic waste into biofuels. There are currently many new developments in plasma technology for the production of biofuels. This in turn is more relevant for recycled waste material, especially for recycled plastic waste. Recycled plastic waste (R-PET for example) has the added advantage of being a relatively consistent material in terms of chemical composition in comparison to other feedstocks, particularily organic waste fractions. This makes fuels made from uniformly biodegradable material and recycled plastics particularly suitable for aircraft engines. Less consistent organic waste and municipal solid waste can be used to produce fuel for diesel engines in the transport sector.
Regardless of the technology actually used, the polymerization of biofuels has always been a major concern. Polymerization has been an important issue because biofuels must be blended with conventional fuels to make them suitable for diesel engines. The exact mixing of conventional fuels with biofuels is of great importance to ensure that the fuel burns smoothly. The same applies to aircraft engines, which require a specific fuel mixture to make them suitable for short-haul flights.
The treatment of biofuels depends essentially on three factors: What do we use as feedstock? This is followed by two sub-points. What is the calorific value of the material? The second sub-point is the following: How consistent is the feedstock and does the material require further pre-treatment?
The second question is: What is the final product we sell?
The third question is: Does biofuel production compete with agricultural production and is the production of the fuel carbon neutral? These three questions determine which biofuel technology we can use to make the solution really economical.