There’s nothing magical about gasoline. It just has several qualities that make it convenient to use as transportation fuel. It’s liquid at room temperature which makes it easier to transport and store than solids or gases. It’s cheap and plentiful. And we’ve already got a lot of infrastructure we’ve already paid for that uses gasoline.
We can make synthesize gasoline, but that synthetic gasoline isn’t going to be cheap. And if octane isn’t cheap anymore, why insist on gasoline as our transportation fuel?
Nuclear power is good for creating heat, but not much else. Nuclear power plants use that heat to power turbines to create electricity. We could greatly expand our use of nuclear plants but a) there is great opposition to nuclear plants and b) very little electricity comes from plants that are powered by oil.
We don’t have the technology to make tiny nuclear plants to substitute for car engines, either, and if people object to nuclear plants far away from them imagine what they would think about being in a car crash with a nuclear plant.
Transmuting stuff to create oil is fantasy.
Nuclear is just not an answer to the oil crisis. There are lots of answers, some of them better than others, that are being tried now. Probably all of them will be necessary. Having giant pools of one of the most versatile and useful substances in technology lying under our feet for the taking made us as a race lazy and stupid. We’re depleting the easy stuff. Everything else will be much harder and more expensive to exploit. There are no easy solutions to substitute.
So, IIUC, a hundred acres of plant matter collects solar energy and turns some of it into carbon. That hundred acres turns into less oil/gas than the energy it took to run the farm in the first place.
The current understanding of petroleum production is that large amounts of algae and plant material was buried generally in a low oxygen , or oxygen less environments (say the bottom of shallow warn seas or lakes). This gunk is a mixture of very large chemical molecules know as kerogen.
The kerogen is then compressed by burrial, and heated (the earth gets hotter as you get deeper) from 60-120C (if you go higher you tend to end up with gas, much above 200C and you get squat)
This pressure and temperature then breaks down (or cracks) the big molecules into smaller hydrocarbon chains.
These light hydrocarbon chains then migrate through permeable and porus rock until they hit an impermeable cap rock and accumulate in a reservoir, or eventually bleed away to surface.
If you wanted to do this artificially, you would need a lot of organic material, a way to compress it (takes energy) and a way to heat it (takes energy). The ammount of energy required would exceed the ammount of energy you got out.
All this energy was provided for free by the natural process.
Minor sidetrack on Synthetic oil that has been mentioned a few times in this thread. Synthetic motor oil is used as a lubricant in most engines, it is almost entirely made from crude oil. Crude oil is not an optimal lubricant for an engine. To get optima properties you can either refine crude and clean out the crap that you don’t want and try modifying some of the hydrocarbon chains. Or you can break the crude down into very simple hydrocarbon components (say ethylene) and the rebuild a desired molecule up from base componets, a process known a synthsis, hence synthetic oil.
So synthetic oil does not mean ‘artificial oil’ rather, ‘a lubricant oil we synthesized from base components (that happened to come from crude)’
You can make synthetic lubricants from non crude base stocks, but it is expensive.
Right, but your handful of Hydrogen and Carbon will stay in their low energy states.
Think of chemical bonds like springs. They hold different atoms together, but they do so in a way that contains a lot of energy. In order to get them to stick together, you have to input energy. I.E. shove them together so they stick. It’s not unlike the difference between a drawn and undrawn crossbow. An undrawn crossbow contains no usable energy, but a drawn one contains a great deal. They are essentially the same, except that the springs on one are loaded. Same deal with Carbon and Hydrogen. A bunch of Carbon and Hydrogen are no different from gasoline, except that in gasoline the springs are loaded. And, like drawing a crossbow, it takes energy to load those springs.
This is a gross simplification, but I hope it illustrates the basic point.
No, just as a crossbow won’t spontaneously become drawn, gasoline won’t spontaneously form. To make them form you basically need heat and pressure.
Yes, but internal combustion is a pretty inefficient process. All of that heat and hot exhaust from your engine is wasted energy. It’s the best choice right now because all of that energy is already there, but if we have to add energy, there are more efficient ways to do so.
But remember that just because we want, say, octane as our product, it doesn’t mean we have to use the same process that created the octane in geologic crude oil.
In other words, gathering a bunch of algae, cooking it in low oxygen and high pressure, then capturing the reaction products, then fractionally distilling the desired end products is an inefficient way of producing octane.
And there’s nothing that says we have to insist on octane as our end product. Vehicles can run on hydrogen, compressed natural gas (methane), ethanol, or larger hydrocarbons (diesel). And there’s nothing that says we have to insist on biomass as our feedstock either. Or that we need a feedstock in the first place.
If we’ve got a bunch of excess electrical energy we could use that electricity to synthesize the liquid fuel of our choice…or we could plug our electric cars in overnight and use the electricity to charge the batteries.
Crude is a mix of long chained hydrocarbons, such as Alkanes, and aromatic hydrocarbons
Gasoline and diesle are a mixture of the smaller chained hydrocarbons present in the crude, such a parafins and alkeens.
To get from crude to gasoline, you basically boil off the lighter stuff and distill it. The heavier junk is left behind. To improve the efficiency you can use a catalyst to crack the bigger chains down to smaller more useful stuff, and blow hydrogen in to break up the chains and unlink some of the more complex hydrocarbons. (known as catalytic cracking and hydro reforming and hydrocracking)
Methane can be made into methanol which is a feed stock for many chemical processes. (Chile has the worlds largest methanol plant which is fed from natural gas reserves that are too far from civilization to be useful for power or heating)
Alcohols can be used to synthesis more complex hydrocarbons as well. t is just expensive and energy intensive.
The trouble with this analogy is that the carbon and the hydrogen ARE in a high energy state. The crossbow is loaded. Hydrogen burns. Carbon burns. So you could run your car from hydrogen, and you could run your car from carbon. The problem is that hydrogen is a gas at room temperature, so you need to compress it, unlike gasoline or diesel which you can just pour into the tank. The problem with carbon (ie, coal) is that carbon is a solid at room temperature so you can’t use it in an internal combustion engine, you can’t just pump it, you need more complex methods of moving it from place to place (in olden times they used guys with shovels).
The advantage of creating hydrocarbons out of H and C isn’t that H and C don’t burn in oxygen, but that hydrocarbons are liquid at room temperature and therefore are easier to work with from an engineering standpoint. Remember that an essential component of an engine that burns fuel is O2 from the air. You need fuel, air, and heat to complete the triangle and get an exothermic reaction.
Doubtful.
First of all, you have to define “amount” - are you talking volume or weight?
Secondly, when you burn Gasoline, you need to break the C-H bonds first, which takes energy, so I’m pretty sure that burning pure H2 and C is a more energetic process.
That may or may not be the practical case, but let’s not mistake that for an example of the laws of thermodynamics biting us on the ass. The energy in the plant matter comes from the sun, not from the fuel used to run the tractors and other processing machinery.
There’s no reason why it absolutely has to be a losing proposition.
To make a multi-faceted question a bit simpler, let’s assume for a moment that acquiring feedstock isn’t a problem. Part of what I don’t have an intuitive sense of is the energy required for compression and heating.
I’m not saying that compression doesn’t take energy, I just don’t grasp the amount of energy involved. Breaking up water to H and O? Sure, I get that the energy it takes to break the bonds is more than the energy you can get from the components. But compression? What happened to “give me a lever, a place to stand on, and a ham sandwich and I can move the world”? I hope that helps explain why I’m blanking on the process.
And heat? Won’t tremendous amounts of heat be generated during the compression process? Is the amount of heat required similar to the water example? But water is the result of combustion; won’t feedstocks have stored solar energy?
If this process proves to be economically feasible, there should be one serving every metropolitan area that produces usable feedstock. Not only does it create fuel, but it cuts the amount of waste to be disposed of.
If this exam is to be believed then the Heat of Formation of gasoline is -250 KJ/Mol. Since the elements are defined to hafe H[sub]f[/sub] of zero, then there is less energy in gasoline than in carbon and hydrogen.
Just because a reaction is thermodynamically possible does not mean that it is kinetically practical. One way to compensate for this is to lower the Gibbs free energy of the final state enough to make it spontaneous. Since the final state of gasoline most likely has a higher entropy than carbon and hydrogen (its difficult to tell for sure, but carbon is one huge very ordered molecule), you can do this by raising the temperature. Raising the temperature takes energy. Typically, the smaller the molecules the higher the entropy, so the higher you raise the temperature, the smaller molecules will be more favored.
You take miscellaneous hydrocarbons (biomass, say), and you convert them into H2 and C. This takes energy, to split the H-C bonds.
You then take the pure H2 and C and run it through some complicated process to produce gasoline. This also takes energy, and it’s not going to be anywhere near 100% efficient. When the Hydrogen and the Carbon combine, energy is released. This energy may or may not be captured and used, but it’s not available in the gasoline.
You then burn the gasoline you created. This releases energy, but first you have to subtract the bonding energy of the Hydrogen and Carbon atoms that are stuck together.
If you just burned the H2 and C, you’d be better off, but it’s still going to take energy to convert biomass to fuel.
I distinctly recall reading a few years ago in Discover or Scientific American (or both) about a machine some guy had which made a form of oil usable as a fuel out of–pretty much anything. You stick chickens and plastics in one end, wait a few days, and out of the other end comes fuel oil.
It was basically just a chemical vat, to my recollection.
It doesn’t take energy to turn H2 and C into gasoline?