The ills of the current energy model are becoming increasingly evident in many environmental and health areas. Since humans became aware of the potential of fossil fuels, there has been no real profound change in how we use them. It is true that we have learned to store electrical energy and even developed fission nuclear power, and that we are using less coal and more renewables, but numerically we are still dependent even today on the remaining oil reserves.

It is estimated that in just 40 years these pockets of crude oil will be exhausted. This is where future alternatives must take advantage of the situation.

One of the most interesting from an environmental point of view is algae-based biofuel, a fossil fuel that is not only renewable but also CO2-neutral.

How Does it work?

The idea is to extract carbon skeletons from living biomass, algae, that grows from the fixation of atmospheric carbon in the Calvin cycle and through the photolysis of water in photosynthesis, giving rise to photo assimilates that will form part of the new biomass in the system.

The advantages of using photosynthetic microorganisms instead of vascular plants are many. Both algae growth and photosynthetic performance are much more efficient, they can be grown in a liquid medium that supplies all nutrients and do not require large surface areas to grow.

To produce biofuel, the biomass must be subjected to precise temperature and pressure conditions, the most commonly used being hydrothermal liquefaction. All of these thermochemical reactions are scalable, which is first designed in small bioreactors to analyze the performance of various growth procedures, algal lineage or other effects to be tested. From a strict chemical sense, this fuel is very similar to what we can produce in traditional refineries.

However, the main advantage is the carbon recovery rate per unit of time. To put it more clearly, it allows us to accelerate a process of incomplete oxidation that would naturally take millions of years to occur under specific circumstances of pressure and dehydration, which ends up lithifying by diagenesis in oil shales or generating crude oil and natural gas, which is nothing more than a mixture of carbonated gases with a greater presence of methane.

All these phases and by-products produced in the monstrous geological cycle of organic renewal of our planet have their analog in the manufacture of biofuel. Of course, another fundamental advantage of this form of energy is its cleanliness. Contrary to what it might seem, the combustion of biofuel does not emit more carbon dioxide than was first removed from the atmosphere by algae growth. In fact, it generates slightly less, because the reactions have by-products with a certain carbon content – the yield is not maximized.

What are the Challenges?

Some of the challenges still to be overcome for biofuel to become a serious alternative in the market include improving overall process performance. To begin with, many by-products are generated in various states of aggregation (gas phases, liquids, complex solid mixtures). Their recirculation is possible in most cases, although a certain fraction of the solid waste still needs extensive study to make the process energetically profitable and environmentally safe.

There are many initiatives using the slogan of the circular economy that try to add unparalleled value to this technology, which is presented as one of the best transitions to an energy model based on nuclear fusion, which will be the irremediable scenario for humanity from 2050 onwards. Moreover, the by-products of thermochemical reactions will be varied and will not only contain carbonaceous skeletons. Living things are composed of a multitude of different macromolecules, the most abundant by weight being lipids and proteins.

After extraction of the biofuel, the amount of lipid derivatives in the residues is depleted, so complex nitrogenous mixtures will be part of this necessary recirculation. From here, chemicals can be extracted for sale to other industries, such as cosmetics.

In some famous start-ups, we can see how they have occupied different niches within biofuel precisely to respond to this need to recycle by-products. Manta Biofuel uses HTL, NeoZeo converts biogas to biomethane, Enerkem transforms waste into biofuel and chemicals.

Another necessary action to further enhance the rate of carbon sequestration is to improve the genetic background. The production of this biofuel depends directly on the concentration of lipids in the cells and the proportion of unsaturated fatty acids (up to 12%). It also depends on the CO2 administered during the scale-up phase. In fact, it will depend on more unknown factors. One way to significantly improve performance is to discover these aspects through experimentation, use artificial intelligence software and systems biology to understand which genes or metabolic pathways need to be modified, and edit the genome of our pre-selected strain, without disturbing the homeostatic algae physiology. In the near future, we will start to see interesting start-ups in this area. It has been on the table at universities for the last two decades.

The Future

Although it is true that biofuel is still far from being a tangible reality in the wholesale market, interest in this product has not ceased to grow in recent years, mainly due to the environmental catastrophe and, above all, to the economic crisis that would entail the gradual depletion of oil reserves without the existence of a substitute with similar energy qualities.

On the other hand, renewables and fission nuclear will play an increasingly leading role until humanity’s best hope, fusion nuclear, becomes operational from 2050 (according to the ITER roadmap). It remains to be seen how things will develop, but it certainly feels inevitable in the mid-term that biofuel will become an energy safeguard.