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Using Seawater To Create Jet Fuel

Scientists from the U.S. Naval Research Laboratory (NRL) have demonstrated significant progress in their novel gas-to-liquid process, which simultaneously recovers carbon dioxide and hydrogen from seawater, and report that it can produce a fuel-like hydrocarbon liquid which may eventually offer a renewable replacement for petroleum based fuel in jet engines. They also envisaged a situation where tiny pores existing in the walls of the vents that housed proton gradients could also have acted as catalytic “proto-cells”, concentrating simple carbon-containing molecules that could have formed from the reaction of CO2 and H2 with the enzyme-like minerals present. These molecules could then have potentially reacted with each other to produce larger, more complex molecules such as amino acids or nucleotides. Russell’s team believe that these more placid vents may have resulted in two critical chemical imbalances. First, when the hydrogen-rich alkaline water from the vents met the acidic ocean water, a natural proton gradient could have been generated within pores of the rocks, which could have been used as an energy source. Second, electron transfer could also have occurred when the hydrogen and methane-rich vent fluid met the carbon dioxide-rich ocean water, generating an electrical gradient.

The ability of Naval Vessels to generate fuel conveys numerous advantages. First off, during conflict this means that the aircraft carrier can maintain a constant supply of fuel without having to spend time away from the mission by returning to land to re-fuel. This time could be significant if the surrounding countries are not friendly forces. Second, fuel supplies are often targeted during conflict, which puts certain countries at an immediate disadvantage if a sufficient amount of fuel cannot be sourced. Generating fuel on-board would immediately remove this risk which has the potential to jeopardize missions.  Seawater is a particularly attractive carbon source for fuel not only because of its obvious abundance, but it contains carbon in the form of CO2 in much higher concentrations than in the air. Scientists at NRL have developed a way to remove CO2 from seawater with a concomitant production of hydrogen (H2), which are the building blocks of hydrocarbons. They achieved this through the use of electrochemical acidification cells.  The production of hydrocarbons, which are compounds solely made up of hydrogen and carbon, from the recovered gases is a two-step process. First, the CO2 and H2 are converted into unsaturated hydrocarbon starter molecules called olefins using an iron-based catalyst. Next, these olefins are converted into a liquid containing larger hydrocarbon molecules with a carbon range suitable for use in jet engines by polymerization. It should be stressed that this is currently a lab-based model system, although the team say that they have made significant advances in this gas-to-liquid system, and proved that the fuel-like liquid generated contained molecules in the required C9-C16 range.  They predict that this technology could produce jet fuel at around only three to six dollars per gallon, which is impressive. With enough investment, they believe that it could become commercially viable in less than 10 years.  In order to demonstrate that the technique works, the researchers flew a radio-controlled internal combustion powered model aircraft using the fuel-like fraction produced by this process, which is shown in the YouTube video below. The team are currently in progress of scaling-up the technique to a commercial channel reactor to increase output, but at this stage it is still a model system.
.A NASA report has compiled decades of theoretical, laboratory and field research in order to give the most detailed picture so far on a popular theory of the origin of life on earth- the “water world” theory. The report has been published in the journal Astrobiology​.  What’s also interesting is that two years ago, researchers investigating hydrothermal vents also came up with a similar proton gradient hypothesis. The team claim that the efficiency of this process is far superior to previously developed techniques for CO2recovery from seawater; this technology removes CO2 at 92% efficiency. Obviously energy will be required as an input to drive the system, and currently this energy is going to come from fossil fuels. It’s not a miracle “green” system that can create renewable energy from nothing, so at the moment there is still a reliance on fossil fuels. But it is not all doom and gloom- if this system can be coupled with a renewable energy source which is also built on the aircraft carrier, for example solar cells, or perhaps even more ideally a small nuclear reactor, then the system has the potential to be very sustainable in the long-term.

There are many theories of how life began on Earth some 3.5 billion years ago. One such theory is that life began from an RNA world. The idea is that since RNA can both store genetic information and catalyze chemical reactions, life may have begun as simple self-replicating molecules of RNA in primitive cells. Over time, DNA would have taken over as the genetic material within cells and proteins would have replaced RNA to catalyze reactions. Another popular theory is that life began at deep sea hydrothermal vents, which are ancient chimney-like structures which spew out mineral-rich water at some 300oC due to tectonic activity. It is thought that the chemicals and energy found at these vents could have provided perfect conditions for primitive life to form. This theory is called the “submarine alkaline hydrothermal emergence of life” or “water world” for the sake of simplicity. Contrary to earlier theories which suggested that life may have begun around a scorching hot and acidic type of deep sea vent called a black smoker, the NASA team believe evidence points to life originating in cooler, gentle springs with alkaline rather than acidic fluids. This was first theorized by Michael Russell in 1989.
Together, this means that in this location we have two potential systems at play which occur today in current life forms; proton gradients and electron transfer. For example, both take place in our own energy making factories- the mitochondria. So we’ve got energy making systems. Is this alone sufficient for life? Probably not. But what these vents also provided was a source of minerals which could have behaved as enzymes, catalyzing reactions as chemicals came into contact with them. Two substrates are thought to have been important for these enzyme-like minerals; green rust and molybdenum. Green rust could have allowed the utilization of the proton gradient to generate molecules that contained phosphate, which in turn could have stored the energy produced. Molybdenum, which is found in our bodies, assists in electron transfer. Although these hypotheses are very difficult to test in the lab, it hasn’t deterred dogged scientists yet.  But the scientists also believe that they can apply this knowledge to searching for life on other planets if they can find liquid oceans, which is exciting. Check out the image below for an example of the replica chimney structures NASA have been creating in their Icy Worlds lab.

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