With environmental concerns growing largely, industries and researchers are looking forward to ways to cut down their carbon footprint without affecting the current lifestyle too much. One increasingly popular way is with the use of biodiesel and biofuels in place of or in addition to standard fuel options. Perhaps newfangled alchemy or an obscure prophecy – whichever the case may be – researchers are doing an excellent job producing new kinds of sustainable biofuels. In a recent study published by Nature, scientists have figured out a way to transform glucose into gasoline. By combining the powers of biology and chemistry, biochemists at the University of California (Berkeley) are converting sugar into hydrocarbons found in fuel.
Olefins are a specific type of hydrocarbons found in gasoline. These comprise a small percentage; however, researchers assert that the process can be well adjusted to generate different kinds of hydrocarbons found in gasoline. Lead experts Zhen Q. Wang and Michelle C.Y. Chang claims that sugar-loving microbes can be cultured to produce olefins, which can be used as an eco-friendly energy source in the future. The experiment consisted of a two-step process involving sugar-eating bacteria and a catalyst. The scientists identified enzymes and catalysts through a series of trial-and-error methods, further testing different molecules with properties that lent themselves to the task at hand.
First, they began feeding glucose to the E. coli strains. Glucose is often the best carbon source for E. coli bacteria as it provides faster growth than any other sugars and is also consumed first in sugar mixtures. Talking about the nature of sugar microbes, Wang jokingly says “these microbes are sugar junkies, even worse than our kids.”
These bacteria were then genetically engineered to produce a combination of four enzymes that would convert glucose into compounds called 3-hydroxy fatty acids. As the bacteria fed themselves with glucose, they began producing more and more fatty acids. To further aid the transformation, a catalyst called Niobium Pentoxide (Nb2O5) was added. The catalyst was used to cut down the unwanted parts of fatty acid molecules produced during the reaction. This resulted in the formation of the final product – the olefins. Olefin content is an important factor in fuel production. These are nothing but unsaturated hydrocarbons. Of course, there is more to the story than that alone!
Olefin is a compound composed of hydrogen and carbon, with at least one pair of carbon atoms. These atoms are linked by a double bond, which makes up the content of hydrocarbons. Sometimes referred to as alkene, olefins can vary in the number of double bonds per molecule, making them mono-olefins, diolefins, triolefins, and so forth. Olefins can also be categorised as either cyclic or acyclic. Cyclic olefins have a double bond between carbon atoms which makes up a closed ring of compounds. On the other hand, acyclic olefins form an open-chain group.
The earliest process of olefin production was by thermal cracking in the 1900s. The technique used high temperatures and high pressure to break up large hydrocarbons into smaller compounds. Olefins can also be produced by other forms of cracking, such as hydrocracking and fluid catalytic cracking. The noteworthy feature of this hydrocarbon is that it has non-fuel applications as well. These can be used as industrial lubricants and as precursors for making plastics. Industrial experts can commercialise the use of olefins by creating building block materials for many products like microplastics, detergents, even adhesives.
While discussing their research further, Wang pointed out that “making biofuels from renewable resources like glucose has great potential to advance green energy technology”.
The method of obtaining olefins follows the simple process of photosynthesis. She explains that glucose is produced by plants, which turns carbon dioxide into sugar and oxygen. Hence, the carbon in the glucose – and later the olefins – are actually produced from carbon dioxide pulled from the atmosphere itself. Scientists say that more research is needed to fully understand the benefit of this new method and if it can be scaled up efficiently for making biofuels and other purposes. One thing is for sure that making biofuels from renewable resources like glucose or glucose-based derivatives can make way for innovative bioenergy technologies.
The experiment also poses a couple of additional questions that are yet to be answered. One of the most important aspects to consider is how much energy will the process consume to produce enough olefins. This is because if the energy cost is too high, the technology will have to be optimised in a way it can be used on a practical level. Another aspect is figuring out a way to increase the total yield. Currently, the researchers used 100 glucose molecules to produce 8 olefin molecules. This ratio needs to be further improved. One way to do this is by coaxing the E. coli strains to produce more of the 3-hydroxy fatty acids for every gram of glucose used.
This research is particularly important to understand the nature of hydrocarbons and to aid the sustainable production of biofuels. Fuels used today like petrol and diesel contain several different hydrocarbon molecules. Paraffins, olefins, and aromatics account for most hydrocarbons in petrol, while diesel is mostly paraffin, aromatics, and naphthenes. Producing olefins can make for a promising start to using biofuels. Additionally, the biochemical synthesis of olefin can be energetically competitive, sustainable, and – in comparison to the established processes – economically feasible alternative for the exploitation of sugar-eating derivatives for biofuel production and consumption.
World demand for energy has been projected to double by 2050 and be more than triple by the end of this century. Since the industrial revolution, the human consumption of fossil fuels has only been growing, becoming one of the most recognised international concerns. The reasons for this can be attributed to the rapidly depleting reserves of fossil fuels. Although advances are made in the field of bioenergy, the immediate solution is perhaps to find simple yet effective fuel alternatives. Currently, most of the ethanol in use is produced either from sugar or starch, but these sources have not proven to be sufficient to meet the growing global fuel requirements. However, the conversion of abundant and renewable resources, including bacteria and microbes, into alternative sources of energy seems to be an effective solution. But for this technology to become viable there is a need to develop cheap and sustainable sources of renewables, along with eliminating the need for pre-treatment processes.
This research thus aims to provide a brief overview of the need for and importance of biofuels; particularly the use of hydrocarbon in gasoline with respect to the growing environmental concerns along with an urgent need to address existing problems like cost-optimisation and large-scale production of biofuels.