Proposed Implementation – wiki

The implementation of biofuels is already becoming reality

The transition from fossil fuel to sustainable ways of allowing for mobility to ensure global trade as well as individual mobility is one of the biggest challenges in our times. Several innovative concepts of sustainable options arose in the past years: hydrogen propulsion, electric cars and – coming now to the focus of our group: biofuel. The great advantage of biologically synthesised fuel in comparison to the other possibilities mentioned is that the existing infrastructure (reaching from engines to gas stations) can be continued to be used. 

So far, biofuel has already been implemented to a certain extent. Bioethanol and biodiesel are partially used for fuelling motor vehicles and so are drop-ins for jet fuel. [5] [6]

Who could use (our) biofuel?

First of all, this depends crucially on the production scale that would be possible. In order to provide all possible consumers with biofuel, it is inevitable to render the production more efficient which is the current problem of producing biofuel with cyanobacteria.

Presuming this issue had been tackled, the end users would be almost all people: Biofuel could be simply used for refueling cars, buses and trucks at gas stations. As mentioned already above, it would be a big advantage that the individual end users would not even have to take grand notice of the change.

Besides, biofuel could also be used by the aviation and shipping sectors. As these are currently big players when it comes to CO2-emissions, the use of biofuel would imply an especially great achievement here. As we aim to produce alkanes, we see our project as particularly useful in the field of developing aviation biofuel.

All in all, the idea is to supply all consumers with renewable, affordable and accessible fuel.

How would the implementation of our project be useful?

Catalytic hydroprocessing is an established technology for producing different kinds of biofuel from precursor material, such as fatty acids and esters. [1] The raw material can derive from different sources, currently used are vegetable oil as well as used cooking oil and animal fat. [2] [3] More recent approaches use oil from algae as feedstock, which is more sustainable as algae do not compete for land with crops and – most importantly – consume CO2 while growing and producing oil. [4]

The idea of our project could be implemented as a further enhancement to this method: We propose a strategy, in which cyanobacteria take up CO2 and produce with the use of light energy alkanes as a precursor for biofuel. Alkanes, unlike fatty acids and esters, do not contain heteroatoms that need to be removed via hydrotreatment. Thus, this energy-consuming step would no longer be necessary for fuel production and the overall energy balance better. 

Apart from that, we focused on developing a protocol for growing cyanobacteria in a normal laboratory instead of a highly specialized one. This is of course still a large difference from an industrial sale but can nevertheless be seen as the first step to facilitating the growing of cyanobacteria.

Challenges and solution approaches

Safety issues

In order to draw on the full potential of the cyanobacteria used for biofuel synthesis, certain genetic modifications will be necessary. We, for instance, proposed a strategy to optimise the alkane synthesis of S. elongatus which consists of several knockouts, overexpression of some genes and if necessary introduction of a modified enzyme. Genetically modified organisms (GMO) always require appropriate safety facilities; the cyanobacterial strain we used cannot cause disease in humans but nevertheless needs to be kept in a BSL-1 laboratory. Of course, this is only a minor consideration while working at a university that has many of those laboratories, but definitely an aspect that should not be overlooked when it comes to implementation on an industrial scale. There will be the need for adequately equipped production sites and trained staff. 

Moreover, there will also be substantial quantities of waste (growth medium that is especially) that also contain GMO and need to be treated correctly. Depending on the extraction process, the bacteria might not survive the biofuel harvesting which would lead to even more waste.

How to ensure optimal growth conditions?

Cyanobacteria need appropriate surrounding conditions to grow in an efficient manner; that means they need a certain amount of light, CO2 and a certain ambient temperature. On top of that, the growth conditions should not vary too much to avoid stressing and hence damaging the bacterial cells.

With respect to the industrial application, the parameter “light” will probably be the most challenging one to deal with: To guarantee the production of biofuel, the cyanobacteria should be constantly exposed to the optimal density of light. This is not ensured when simply using daylight, as this is dependent on weather, time of year and with this also on location. The solution would be artificial light sources. On the one hand, this does reliably work (we also used LED light strips in order to grow our cyanobacteria inside an incubator), on the other hand, one would need to calculate the balance to see if the energy and emissions saved by the use of cyanobacteria would still be higher in comparison to the energy input through artificial light. A big advantage of artificial light is obviously that the production is able to continue at night.

Moreover, difficulties might lay in the construction of the tanks that contain the bacteria: In large tanks, the light will only reach into the middle of the volume with a lower density which would render the production more inefficient. Tanks with a larger surface would be the solution but in turn are unhandy in terms of space-saving. 

Also, one has to think about where to install the light source. Either, one needs translucent containers (made of plastic or glass like typical laboratory equipment) or separate light sources in each container that are in touch with the medium.

For cyanobacterial growth, it will not be sufficient to rely on the outside temperature because of its fluctuations and simply because it is (most of the time) too low. Even room temperature was not enough in our experiments. A heater of course would again consume energy and with this have a negative effect on the overall balance of the process. This is why we propose to couple biofuel production to big factories that produce heat as a waste product. In this symbiotic scenario, the heat energy would be fixed and in fact recycled. 

The same can be envisioned for the CO2: For optimal growth and highest-possible CO2-uptake, the ambient CO2-concentration should be far higher than the atmospheric concentration of 0.04%. It would be a win-win scenario to redirect the CO2 emissions coming from a power plant into the tank containing the cyanobacteria.

How to make it a reliable source?

In order to actually implement biofuel production, it has to be ensured that it is a reliable source. Otherwise, its use in real-life could just remain an optional add-on to the existing infrastructure. This would be an advance, as seen from now, but not the final aim.  As described above, the growth conditions need to be constant for constant production. Moreover, there has to be refined logistics to organize the network of production sites and distribution to the consumers. A great advantage of bacteria is that they can grow anywhere in the world. Local energy production is an important step as it allows for avoiding the energy consuming transportation of fuel via pipelines, ships and trucks. Moreover, it is economically and politically attractive to ensure independent fuel supply.


[1] Starck, L., Pidol, L., Jeuland, N., Chapus, T., Bogers, P., & Bauldreay, J. (2014). Production of Hydroprocessed Esters and Fatty Acids (HEFA) – Optimisation of Process Yield. Oil & Gas Science and Technology – Revue d’IFP Energies Nouvelles, 71(1), 10.

[2] Digambar Singh, Dilip Sharma, S.L. Soni, Sumit Sharma, Pushpendra Kumar Sharma, Amit Jhalani,

A review on feedstocks, production processes, and yield for different generations of biodiesel, Fuel, Volume 262, 2020, 116553, ISSN 0016-2361,

[3] Ramos M, Dias APS, Puna JF, Gomes J, Bordado JC. Biodiesel Production Processes and Sustainable Raw Materials. Energies. 2019; 12(23):4408.

[4] Changyan Yang, Rui Li, Chang Cui, Shengpeng Liu, Qi Qiu, Yigang Ding, Yuanxin Wua, Bo Zhang. Catalytic hydroprocessing of microalgae-derived biofuels: a review. Green Chem., 2016, 18, 3684, DOI: 10.1039/c6gc01239f.

[5] Geleynse, S., Brandt, K., Garcia-Perez, M., Wolcott, M., & Zhang, X. (2018). The Alcohol-to-Jet Conversion Pathway for Drop-In Biofuels: Techno-Economic Evaluation. ChemSusChem, 11(21), 3728–3741.

[6] Standard Specification for Aviation Turbine Fuel Containing Synthesized Hydrocarbons. ASTM International. Retrieved October 10, from