Biofuel requires somewhat flexible equipment during the production and storage phases due to the often intense forces required to turn biomass into fuels that can be used as a drop-in replacement for existing engines.
This means that they need careful management of environmental conditions and pressure relief systems that can manage the sometimes variable conditions required during the fermentation processes.
The appeal of biofuel is sustainability, not only in terms of minimising the use of fossil fuels but also in terms of minimising carbon emissions, something that can be very different in certain industries such as shipping.
This makes the news that a company has produced a carbon-negative biofuel blend successfully used on a commercial vessel very welcome, as shipping and flight are the two most difficult challenges for biofuels but ones that need to be challenged to make net zero a possibility.
This leads to the question of how this is possible; what makes biofuel carbon negative and how can it be achieved at scale with the right equipment?
What Does It Mean To Be Carbon Negative?
Businesses are increasingly mindful of their carbon footprint, or the amount of carbon emissions their actions, production processes and purchasing decisions will create.
Generally, the goal is carbon neutrality, which is where the carbon dioxide they release is balanced by the carbon dioxide they offset, absorb or capture, which ensures that no extra carbon dioxide is added to the atmosphere.
Carbon negativity goes further than this and is a process which absorbs more carbon dioxide from the atmosphere than is emitted through the production process.
For example, if a biofuel was made from plants, algae or other materials that absorbed more carbon as part of photosynthesis than was produced in the process that converted them into biofuel, then they could be considered carbon negative.
What Counts Towards Carbon Cost?
One of the complexities in exploring the achievement of a carbon-negative biofuel is ascertaining what has been counted as relevant carbon capture and relevant carbon emissions.
For example, the company which made the carbon-negative biofuel is counting the whole-life carbon cost, which includes the growth of cashew plants in India and the effects of the biochar produced during the pyrolysis process which is used in sustainable agriculture.
One tonne of biofuel is linked to 5.7 tonnes of carbon dioxide being taken out of the air and becoming part of the soil due to the biochar co-product.
Quantifying these co-products is tricky at the best of times, and highlights how complex carbon neutrality in biofuel is because the point of absorption and the point of emission are often at very different points in the life cycle of the biofuel.
However, at the same time, they only count the process that is relevant to their fuel; they do not take into account, for example, the fact that the biofuel is 20 per cent of a blend that includes traditional and very polluting marine fuel.
At the same time, however, 20 per cent is better than nothing and may still be less ecologically harmful than some of the green alternatives also proposed.
What Is A Drop-In Fuel And Why Is It Important?
The biggest advantage the fuel has is that it can be used as soon as it becomes widely available because it has been designed as a drop-in fuel.
Many biofuels require engines and turbines that are either designed or adapted to use them because whilst they serve the same purpose as fossil fuels, they often have different properties.
This was why flex-fuel cars in Brazil were different to petrol or diesel cars sold anywhere else.
A drop-in fuel, by contrast, is one that could be used as a replacement or in a blend with an existing fossil fuel without any undesirable side effects or damage to the mechanisms.
They are one of the most important development strands in the fuel sector because they allow for existing vehicles to continue to be used whilst reducing their carbon cost.
This is essential for industries which are uneconomical if not outright impossible to run using other carbon-neutral energy sources such as electric motors.
This includes shipping as well as commercial air travel, which also has to contend with extreme temperatures and environmental conditions far beyond what many conventional batteries and conventional fuels are designed for.
There have been other types of renewable carbon-neutral biofuels that have been proposed using ammonia or green hydrogen, but both would require fundamental changes in engine construction to be used, whilst the drop-in biofuel would work with standard marine engines.
