Stretching German Gasoline Supply. (1 Viewer)

[parsifal]

steve summarises the situation precisely gentlemen, and no amount weaving and jinxing is going to get around those basic home truths im afraid.

There are some ironies to reflect upon. Oil was available in both Libya and French north Africa, but not developed or even the extent of the reserves known. I wonder what might have happened if the reserves in Tripolitania had been more rigourously investigated and developed in the mid 1930s.

Another great imponderable is if the germans had somehow managed to capture the Iraqi oilfields in 1940. if that had been done intact who knows what might have happened.

Oil is discovered in Libya in 1959.

 

[Koopernic]

Methanol Synthesis was probably the only process that was efficient enough to not require absurd amounts of coal and which had the least capital plant requirements to limit building construction. A fairly mature technology, I believe ICI was considering such a plant in the 1920's. Of course it requires specialised engines to exploit, an unattractive proposition.

I have no great faith in biofuels now, except maybe algae and have little hope for them in the 1930s. Europe was starving due to blockade and there was no spare crop land to dedicate to fuels. Perhaps wood chip waste.

The synthesis via the route syngas->butanol->butylene->iso-octane is interesting as it could produce a high quality product in which it was possible to very accurately trade off output of butanol versus methanol production. The chromium catalysts took in syngas and produced 17% butanol with the balance Methanol and traces of gases, propanol. The methanol could easily be converted to more butanol via cycling through the catalyst. The butanol could eventually be converted to iso-octane. I don't imagine it would be more than 20%-25% efficient but it was a very high grade pure product that didn't required down stream separation from other hydrocarbons. If they could be made small and modular enough they would allow dispersal.

The Bergius Hydrogenation plants were very efficient in terms of coal perhaps over 60% (but required capital and steel) they produced considerable amounts of propane's and butanes. These could be used in LPG to power vehicles, really the entire German commercial transport fleet could have run of this LPG but they couldn't build the required 600,000 vessels. Moreover the propanes and butanes could be subjected to acid alkylation to produce very high grade gasoline (this was the process that allowed the RAF to switch from 100 octane to 100/130). The source of butane for the polymerisation to iso-octane also switched to these gases from the hydrogenation plants thus eliminating the need for syngas production in many cases.

Hence the hydrogenation plants could become the centre of iso-octane and alkylate production as well as direct production of gasoline and diesoline. They were by nature big and expensive and therefore targets that could not be easily dispersed.

This seems to be what happened.

Another possibility is fischer-tropsch plants that produce gasoline (only 46 octane) and some diesel in which any other product is simply burned of to produce electricity thus bypassing the need for elaborate separation facilities. Mixed with the iso-octane and TEL a reasonable fuel could be produced. This process was considered viable in the 1970s and might have been integrated with coal fired power stations. The Germans were at the time capable of producting a sort of turbo-supercharged boiler which was efficient and took of some power from the turbo (which could be water cooled). The latter stage of the war demonstrated some uranium based catalysts that produced more reasonable gasoline.

The Karrick process basically steams of about 1 Barrel of oil per ton of coal, this barrel of oil produces about 25% gasoline and 30% diesel straight out (without cracking) as well as large amounts of combustible gas and semicoke that can be used to make town gas and electricity. This simple process seems to have been the main supply at the end of the war and they plants could be small and hidden.

As far as I can see it the most efficient process was methanol production but that required new engines, itself very unattractive.

Hybrid systems are conceivable, Karrick to make gasoline/diesel, the gas used to make electricity or syn gas and the semi coke used for syn gas or electricity production. The syn gas could then be used to make butanol methanol.

Of course this all takes time and they didn't have that much time considering the first plants were only operating in the late 1930's.

 

[kool kitty89]

I just discovered this very informative site:
AMF - Advanced Motor Fuels

Very relevant to this discussion, and just interesting in general from a fuel science/engineering point of view.

Among other things it has more specific details on butanol than I'd previously managed to find:
AMF - Advanced Motor Fuels

Isobutanol has the best overall qualities as a gasoline substitute or additive, but Tert-butanol's lower boiling point (and higher vapor pressure) combined with high octane performance makes it quite useful as long as it's dissolved in another liquid fuel (like any other butanol isomer, isopropanol, ethanol, methanol, acetone, suitable hydrocarbons, etc) to suppress its relatively high freezing point. (it's unusual in having a fairly narrow liquid range at standard pressure, but its combustion qualities are relatively good)

Methanol Synthesis was probably the only process that was efficient enough to not require absurd amounts of coal and which had the least capital plant requirements to limit building construction. A fairly mature technology, I believe ICI was considering such a plant in the 1920's. Of course it requires specialised engines to exploit, an unattractive proposition.

I have no great faith in biofuels now, except maybe algae and have little hope for them in the 1930s. Europe was starving due to blockade and there was no spare crop land to dedicate to fuels. Perhaps wood chip waste.

Biofuels are difficult to implement as the primary fuel source, but fairly useful as a supplemental one, namely using various forms of waste or relatively low yield animal feed (like chaff/hay -which itself could be waste otherwise slated for open burning depending on the situation). Fuel crops that cannot double as food crops are generally a bad idea given the range of high yield crops that can be adapted to either role, particularly those useful for both human consumption and animal feed. (the US has a rather heavy fixation on corn and to lesser extent wheat, but oats tend to be rather high on the list for useful food+biofuel crops, and would obviously fit in well with cool/temperate regions while also remaining quite cold/frost tolerant -there are also hot weather tolerant varieties like red-oats which I suspect are among the rather invasive weedy 'wild oats' scattered about locally here in the San Jose/Santa Clara Valley area of California -they coped with the drought rather well too, though this isn't particularly relevant to Germany ... perhaps more arid portions of Italy though, which certainly had an energy crisis of their own during the war)

Oats would also fit well with the horses still pervasive in German transport/farm/etc use (though a pre-war shift on heavier mechanization would still be a major target -methanol fuel optimized industrial farm equipment might have even been a bit easier to target than general automotive use). Grass feed for farm or work animals is extremely inefficient and likely better employed as biofuel. (though obviously reasonable quality hay has other practical uses than feed)

Proper processing of biomass to sort out fractions (like the aforementioned chaff) to collect the ash for reprocessing into fertalizer (among other things) and partially replenish soil of depleted nutrients.

Wood waste is, of course, also useful, and any sort of organic waste easily dried and transported to processing/synthesis plants. (municipal/household waste might have been reasonable to sort similar to recycling and scrap drives, but the likes of processing sanitary waste -namely sewage- might be a bit much to ask for war-time application, particularly with the high percentage of water content involved -not really useful for a biomass source until you get into common industrialized recycled water production that already includes most relevant organic solid waste processing as part of their function)

Wood and other plant waste (and coal for that matter) should undergo destructive distillation (charring) prior to being subjected to steam for conversion to syn-gas, sorting out useful destructive distillation products (including tar and methanol -though the latter may be preferable to re-circulate through the system anyway along with hydrogen and carbon monoxide 'wood gas' and 'coal gas' fractions). The aromatic fraction of wood tar would be useful for octane boosting additives among other things (even some solid aromatics like napthalene can be useful when dissolved in a suitable solvent fuel) while resin-heavy woods like pine would also produce a great deal of turpentine, also useful as a fuel or solvent. (some grades with relatively high octane values on their own -at least as a low-grade starting point useful for boosting with other additives, and adding enough easily vaporized fractions to function well as a substitute for standard gasoline blends -turpentine fuel was discussed previously, along with various engine times using them, including ones compensating for poorer vaporization qualities -I suspect additives easing vaporization/ignition would be preferable, though)

In terms of farm equipment, conversion of methanol to dimethyl ether would be another simple synthetic fuel option if diesel cycle engines were preferred. It's a gas at standard temperature and pressure, but liquifies easily under modest pressure similar to butane. (to the extent that it may have avoided the issues of pressure vessel production that hindered use of LPG -propane and ethane certainly require much stronger pressure tanks than butane or DME) DME would also be a useful additive for improving volatility of synthetic fuels (and other natural/synthetic fuel blends lacking proper volatility for carbureted engines -like certain kerosene/naptha or turpentine grades of suitable octane rating for boosting to gasoline standards, but unsuitable volatility -same goes for butanol and aromatic hydrocarbons) Diethyl ether could be similarly used, depending on its availability, and is less volatile (and liquid at STP) but still a good engine-start/carburetor function booster. (really, having volatility good enough for reliable cold-start is the main requirement here, and avoiding the need for dedicated starter fluid)

On a side-note, DME would probably have been a much more practical starter fuel for Heinkel's Jet engines than hydrogen gas (I'm not sure if Ohain's engines ever got beyond their hydrogen-fueled warm-up requirements, but I know the original HeS 3B had to employ such -rather like a blow lamp burner's vaporizer warming up). Methanol might have worked reasonably well too (given the smokeless flame even when running rich, thus not clogging the injectors during warmup) but DME seems simpler given its gaseous state.

The synthesis via the route syngas->butanol->butylene->iso-octane is interesting as it could produce a high quality product in which it was possible to very accurately trade off output of butanol versus methanol production. The chromium catalysts took in syngas and produced 17% butanol with the balance Methanol and traces of gases, propanol. The methanol could easily be converted to more butanol via cycling through the catalyst. The butanol could eventually be converted to iso-octane. I don't imagine it would be more than 20%-25% efficient but it was a very high grade pure product that didn't required down stream separation from other hydrocarbons. If they could be made small and modular enough they would allow dispersal.

The site you linked previously: Technical Report 248-45 - Section V Isobutanol Synthesis
here: Amateurs study aircraft design. Professionals study oil production.

It has a rather nice complete list of byproducts from the initial synthesis (aside from methanol which is recirculated), not just isobutanol, but the majority of alcohols and ketones, possibly some of the aldehydes and hydrocarbons too, such that a modestly refined (distilled) blend of those byproducts and intermediates alone would make a good additive for gasoline or the makings of a high-grade fuel (like aviation fuel) on its own. Of course, with alcohols present, TEL should be avoided due to its detrimental impact and general incompatibility. (aromatics and other organic boosters would work fine in the blend) In fact, it might be best if German had avoided securing a TEL license altogether and stuck with lead-free alternatives pre-war. (and thus already had a head-start on addressing some common engineering difficulties with ethanol/methanol additives among other things and their impact on engines, fuel tanks, pumps, seals, and hoses, etc -plus not spewing out all that leaded vapor to breathe in is a nice bonus)


I would expect the combined efficiency of using most/all of the direct isobutane + byproducts of that process to be quite a lot closer to the 60% efficiency of pure methanol synthesis, and far better than the full isooctane synthesis of only 20% thermodynamic efficiency. (energy density of most of those products is also high enough to be reasonably useful in aviation fuel, though removing some of the more energy poor fractions like ethanol -not to mention adding energy rich fractions of aromatics- would improve that further, while overall octane rating would be considerably higher than even late-war C3 aviation fuel, allowing consistently higher boost pressures and/or compression ratios -stretching fuel supplies more by blending in lower octane gasoline blends would compromise that to some degree, but possibly slightly improve base energy density as well)

Also remember that blends of various liquids (particularly polar oganic compounds -like alcohols and ethers and ketones) can quite easily be significantly denser than their constituent components. This won't improve energy density by weight, but will improve it by volume. (this would be more significant for ground vehicles where volumetric space is more important than weight -though both are obviously important on aircraft as well) Methanol being the smallest of these molecules, 'packs in' rather well with most others, rather like water does. (the typical school laboratory demonstration is mixing water with anhydrous -or 90+ % isopropanol in a 50/50 ratio and demonstrating a significant decrease in volume)

The Bergius Hydrogenation plants were very efficient in terms of coal perhaps over 60% (but required capital and steel) they produced considerable amounts of propane's and butanes. These could be used in LPG to power vehicles, really the entire German commercial transport fleet could have run of this LPG but they couldn't build the required 600,000 vessels. Moreover the propanes and butanes could be subjected to acid alkylation to produce very high grade gasoline (this was the process that allowed the RAF to switch from 100 octane to 100/130). The source of butane for the polymerisation to iso-octane also switched to these gases from the hydrogenation plants thus eliminating the need for syngas production in many cases.

Properly planned, I'd think hydrogenation and Fischer-Tropsch synthesis would complement eachother rather well, even pre-war, with each having notable advantages. (and, among other things, methanol and isobutanol synthesis -and byproducts- could be combined with hydrogenation plant gasoline along with conventional petroleum derived gasoline -or bituminous coal derived base fuel stocks, non-gasoline fuel grades like kerosene/naptha still useful for boosting into gasoline engine specs, etc)

From a strategic standpoint, the (potentially hardened) centralized hydrogenation plants combined with smaller, dispersed (and non-dispersed) cheap/fast to set up and replace fischer-tropsch synth plants had plenty of potential to develop a pre-war (or pre-Nazi, for that matter) energy development plan around. The earlier such plans were started, the easier to have the entire industry develop around that technology rather than standard (leaded) gasoline tech.

Of course this all takes time and they didn't have that much time considering the first plants were only operating in the late 1930's.

In that regard, the Fischer-Tropsch plants (once the base technology was established) could have been pursued much more rapidly, and any flaws and setbacks in early plant designs would also be relatively inexpensive to resolve and address moving forward given the low capital overhead intrinsic of such plants.

The obvious time to seriously push such technology would be when TEL production was first being considered, and thus when an alternative route for octane boosting could have been chosen outright. (and initially supplemented by more conventional industrial production of alcohols and aromatics -and ketones, etc- while also investing in engineering solutions for potential corrosion issues caused by some additives)

Pure methanol also would have been the oldest/simplest octane boosting gasoline additive, and while corrosion issues aren't really worse than ethanol (more just different than objectively worse), the bigger issue would be the air/fuel mixture impact when significant fractions are introduced. (adjusting the choke could compensate for this, but more elegant long-term solutions would be preferable) Still, additions of methanol in the 5-10% range should have kept air/fuel mixture behavior reasonably close while still notably improving combustion qualities (knock resistance). Methanol's better vaporization qualities and failure to form an azeotrope with water makes it more attractive than ethanol as an additive too. (especially fermentation derived ethanol -petroleum derived ethanol can somewhat more efficiently be produced anhydrous and avoid quite a few problems specific to 190 proof ethanol)

Dehydrating methanol to DME and injecting it into diesel fuel stock to improve the cetane rating could be another application in limited quantities, especially for winterized blends. (Diethyl ether could be used in larger portions, be it petroleum derived or otherwise, but of course diesel has more specific lubricity requirements that makes dilution a bit more complicated than with gasoline engines, particularly with varying seasonal blends)


The current European Gasoline blend standards should also be of interest:
AMF - Advanced Motor Fuels (more so for the butanol content)