PolyoxymethylendimethyletherOccasionally Oxyjethylenether oxymethylenether deluged with inquiries about a particular news story. That happened this week. As the inquiries mounted, I decided I better oxymethylenether the story. Recently German car manufacturer Audi announced they can economically produce carbon-neutral oxymethylenether fuel from ingredients found in the atmosphere:. Audi has successfully made diesel fuel oxymethylenether carbon dioxide and water.
Polyoxymethylendimethylether – Wikipedia
Occasionally I am deluged with inquiries about a particular news story. That happened this week. As the inquiries mounted, I decided I better address the story.
Recently German car manufacturer Audi announced they can economically produce carbon-neutral automotive fuel from ingredients found in the atmosphere:. Audi has successfully made diesel fuel from carbon dioxide and water. German car manufacturer Audi has reportedly invented a carbon-neutral diesel fuel, made solely from water, carbon dioxide and renewable energy sources. Many people have already suspected that there has to be a catch.
Of course there is. This process requires carbon dioxide to be captured from the air, and hydrogen to be produced from electrolysis. It is true that the atmosphere — nitrogen, oxygen, water vapor, carbon dioxide — contains all of the ingredients necessary to make all sorts of unimaginable things.
The raw ingredients are there for fertilizer, pharmaceuticals, plastics, and certainly fuel. But the key ingredients, carbon dioxide and water, are the products of combustion. Burning diesel creates carbon dioxide and water. Converting them back into diesel takes a lot of energy. Think of fuel as a rock at the top of a hill.
It has a lot of potential energy. Roll the rock down the hill and that potential energy is released. This is similar to burning fuel to create carbon dioxide and water.
Now, if you want to turn that carbon dioxide and water back into fuel, you have to carry the rock back up the hill. According to the laws of thermodynamics, it always takes more energy to carry that rock up the hill than you get from rolling it back down. In other words, the process is necessarily an energy sink.
It is a dead certainty that more energy is required to produce this fuel than can be released by burning the fuel. But is that a problem? If you have a readily available and cheap energy source, it could make sense to produce fuel via a process that is an energy sink.
Yes, this would be an energy sink, but one using a nearly limitless source of energy. And if the value of the hydrogen is greater than the cost of the inputs, this may be a worthwhile process despite the fact that it is an energy sink. This is essentially the claim being made by Audi. If this is you, you can jump right over this section to the conclusions.
In order to produce 1 ton of fuel, this process reportedly requires capture of 3. That in turn requires kilowatt hours kWh of electricity and 1, to 2, kWh of thermal energy per ton of carbon dioxide. In my experience, the high end of these ranges is generally more representative of actual operations, while the lower end represents projections and best case scenarios of much larger projects. The average price of electricity for industrial users in the U.
In the European Union prices are quite a bit higher than that. The most recent data showed an average price of 0. In Germany , where Audi is based, the cost of electricity is about 16 cents per kWh. If we use the lowest cost here — the price for industrial users in the U. Presumably this thermal energy is for shifting carbon dioxide into carbon monoxide via the water-gas shift reaction, which is required for the fuel synthesis reaction as described below.
The average of the given range is 1, kWh of thermal energy per ton. This is equivalent to 6 million British thermal units MMBtu almost exactly the energy content of a barrel of oil. Like electricity, natural gas costs in Europe would be significantly higher. The other main ingredient in the process is hydrogen. If we take a carbon chain length as representative of diesel fuel which is right in the range of diesel length hydrocarbons then the reaction becomes:.
Therefore, we can calculate the theoretical minimum of how much hydrogen this reaction is going to require per ton of fuel produced. If we convert all units of weight into units of molecular mass, we can solve the rest of the equation. C 12 H 26 has a density of 0. We can cross-check our calculations by noting that this much C 12 H 26 contains 70, moles of carbon i. In comparison, the 3. Hydrogen is very light, with a molecular weight of 2 grams per mole, so this converts to , grams, or kilograms of hydrogen.
How much might that cost? This is where they make some assumptions that may not hold up well over time. They assume they will use wind and solar power to produce the hydrogen, and that this can be cheaply done. They calculated that base hydrogen costs i. So that helps us to factor in the cost of hydrogen into this analysis. The vast majority of that cost is due to the hydrogen, so the assumptions made about hydrogen production are where the greatest sensitivity to price will be. Keep in mind that these are only the costs for the primary feedstock inputs.
These can easily add several more dollars per gallon to the costs. While the lower end of this range appears to be overly optimistic, the upper range may be achievable keeping in mind that we have made some very generous assumptions regarding their process. On the flip side, the current spot price of diesel in the U. To sum up, can Audi produce fuel from thin air? There is no question about technical viability.
However, they are also not the first to make this claim. The question boils down to economic viability, which appears to be challenging given what has been released about the process. Also keep in mind that Audi has only done this process at very small scale.
These projections were based on lab scale experiments. Audi has now scaled the process to liters per day, which is about 1 barrel per day. They will now gather data at this scale, and either firm up or contradict some of their assumptions about the process. If everything works as hoped, they will then need to scale up again to something in the to 1, barrel per day range. These scale-up steps are like gates that must be successfully passed, and historically most seemingly promising processes fail to pass through those gates for various reasons.
As a result, one should never take too seriously a cost estimate for fuel production from a commercial plant when the data is derived from experiments at a much smaller scale. It is important to note that because this process is an energy sink, it could exacerbate carbon dioxide emissions. You could possibly pull that off in an environmentally-friendly way with 3 BTUs of solar power input and 1 BTU of diesel output, but if you use natural gas instead, then that 1 BTU of diesel output may generate the emissions from 3 BTUs of natural gas input.
In a case like that, it would be better to use that fossil fuel input directly in an engine if possible than to utilize it to produce a fuel in a process that is an energy sink.
They constitute a vision of reality. I consider this very worthwhile and fascinating research. I am simply attempting to offer a more complete and realistic perspective in light of the uncritical reports by the mainstream media.
Link to Original Article: Robert Rapier is a chemical engineer who works in the energy industry. Robert has over 20 years of international engineering experience in the chemicals, oil and gas, and renewable energy industries, and holds several patents related to his work.
He has worked in the areas of oil refining, natural gas production, synthetic fuels, ethanol production, butanol production, and various biomass to energy projects. Robert is the author of Power Plays: Energy Options in the Age of Peak Oil. The story suggests that Audi engineers made basic mistakes or its management made dubious claims. Both are unlikely, considering the name and history of Audi.
Whether their power-to-Diesel plants will be viable depends mainly on the price of electricity. Such plants will do the same as the German aluminum melters.
The Futures show a continued downward tendency for the next years. As the capital and fixed operating costs for these plants will be relative low, it will be also optimal for these plants to buy only electrictiy and run only if the price is low and run only part of the time.
Obviously, the right source of carbon-free sustainable energy for this process is the nuclear breeder reactor, either LFTR or IFR design, both pioneered successfully in the USA, and blocked by my friends in the environmental and anti-nuclear-weapons camps, who cannot distinguish between gasoline for an automobile, and a Molotov cocktail.
Furthermore Aluminium is normally operated as a continuous smelting operation. Thus they tend to be located near generators that can provide long twerm and low cost contracts like hydropower. They do not normally drop load though one example of such occured during the power crisis in Europe How about hemp seed oil as bio-fuel? Leaves can be dried for hay for livestock. Oil cake is rich in complete protein as well as traces of essential fatty acids.
Long fibers of outer cortex of stems make good fiber for textiles. Not only are they likely, you can take it to the bank. They made dubious claims. They simply assumed dirty cheap electricity, and that they could run this process on dirt cheap intermittent power. But if you could consistently get dirt cheap electricity, why are Germans paying much higher electricity prices than the U.