Researchers took a big step towards commercially generating clean renewable fuel by confusing the harmless gut bacteria E.coli (Escherichia coli) into producing renewable propane instead of cell membranes. Their ultimate goal is to insert this engineered system into photosynthetic bacteria, to directly convert solar energy into chemical fuel.
"Although we have only produced tiny amounts so far, the fuel
we have produced is ready to be used in an engine straight
away," Dr Patrik Jones of the department of life sciences at
Imperial College London said of the research, conducted jointly with the
University of Turku in Finland.
Although conclusive results are still some way off (possibly 5-10 years), commercial production is a very optimistic prospect, given the benefits.
The next step is to make the process low-cost and economically sustainable.
Owing to its lower carbon content, propane is an inherently clean fuel . There is also an existing global market for it. It is a by-product arising out of natural gas processing and petroleum refining and can easily be liquefied.
In fact, propane makes up the majority of liquid petroleum gas (LPG), one of the most used forms of fuel on Earth, powering everything from heavy machinery to household appliances.
Because natural gas and refined petroleum are both exhaustible, a clean and renewable propane extraction is a win-win alternative.
“Fossil fuels are a finite resource and as our population continues to grow we are going to have to come up with new ways to meet increasing energy demands. It is a substantial challenge, however, to develop a renewable process that is low-cost and economically sustainable. At the moment algae can be used to make biodiesel, but it is not commercially viable as harvesting and processing requires a lot of energy and money. So we chose propane because it can be separated from the natural process with minimal energy and it will be compatible with the existing infrastructure for easy use” added Dr Jones.
The technique consists of interrupting the bacteria’s natural process of creating cell membranes out of fatty acids by using three different enzymes with separate functions. They fooled the bacteria into making propane by employing the new aldehyde-deformylating oxygenase (ADO) enzyme that naturally creates hydrocarbons. The role of ADO was enhanced with the use of electrons, enabling the enzyme to greatly boost its catalytic capability, leading to the production of propane.
Although the quantities produced were one thousand times less than those needed for commercial purposes, the researchers believe it is only a matter of refining the process now.
Dr Jones said: “At the moment, we don’t have a full grasp of exactly how the fuel molecules are made, so we are now trying to find out exactly how this process unfolds. I hope that over the next 5-10 years we will be able to achieve commercially viable processes that will sustainably fuel our energy demands.”
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