Does China push DME as diesel fuel or a propane substitute?

DME is frequently made from methanol. Methanol is made from synthesis gas, a mixture of carbon monoxide and hydrogen.

China makes much of its synthesis gas from coal but most production in the world is from natural gas. DME, as mentioned, can be used and stored much like propane, but, unlike propane, it can be easily ignited by injection into a diesel engine. Propane can be mixed into the intake air of diesel engines but requires diesel, or DME, injection to ignite it. DME produces almost no carbon particulates in diesel engines; neither does methane.

China should build many coal to methanol factories at its coal mines, and methanol should become the automotive fuel of choice for china. This will greatly reduce China's need for oil. Also methane should be produced at the mines. There are many contaminated mine wastes that contain much energy, but are not worth shipping.

A highly neglected possible fuel is pure carbon powder that can be made by several processes out of coal and all form of biomass. Pure carbon can be burned in combined cycle gas-turbine power plants at the highest efficiency.

Unfortunatly China did not like its two CANDU power plants well enough to build several more over the past few years. CANDU power plants can be built faster than many others because very heavy industry is not needed for their construction. Natural uranium can be used as a fuel. China could even buy the "spent" rods from US reactors and use them directly as fuel, since they still have 95 percent of their energy left in them. This would eliminate the need for the US congress to fight about where they should be put for tens of thousands of years. The US does not have to store them for thousands of years, they can just use them or sell them, or pay someone to take them and use them.

China can balance its use of carbon by nuclear powerplants, since the US refuses to do it. ..HG..

"China should build many coal to methanol factories at its coal mines, and methanol should become the automotive fuel of choice for china. This will greatly reduce China's need for oil."
Henry,
Can you explain how you come to this conclusion? You mention the 'clean' burn and easy and versatile handling and compatibility of D.M.E., but then go on to suggest methanol as automotive fuel.
Is there a major penalty re processing behind this observation?
I understand that D.M.E. suffers a penalty in this regard, but NG or natural methane also suffers an implied penalty as the quality assurance specification rises. This may not be so important in high tolerance application but for Aero or high spec application where max control for emissions, power output or reliability (consistency) or handling hold a higher priority, then D.M.E. may return a better efficiency ?

Methanol can be produced easily from many sources including natural gas, wood, charcoal, sugar cane leaves and stalks, grass, coal, crude oil, organic wastes, geothermal and even nuclear power plants. It is liquid over a wide range of temperatures. It dissolves immediatly into water so tanker and fuel spills are less of a clean up problem. Damage to wild life is limited by the fact that even the largest spills are a small fraction of the water available for dilution and micro-organisms rapidly eat it. It burns cleanly in simple burners and may be safer in such use than propane. It can be transported in simple containers. Simple mantle pressure lamps can be adapted to use it for lighting, and Vaporejet has a new vaporizer that would simplify such lamps. It has very high octane for use in high efficiency engines that can approach the efficiency of diesel engines. It is now being used directly in small fuel cells. It is quickly bio-degradeable. It can be used to produce many chemicals. Its conversion into DME, dimethylether, is possible, without much energy cost, for use in high efficiency diesel type engines. It has been used to feed yeasts in the production of animal feeds. It might even be possible to feed it directly to ruminant animals.

Methanol cannot be used as the sole fuel in diesel type engines because it will not ignite upon injection. DME, on the other hand, has superior injection ignition properties but is a gas at ordinary pressures and can be stored as a compact liquid in propane type tanks at propane type pressures. DME may even be able to be burnt in propane appliances without modification. DME has no sulphur in it and its chemical structure, with no two carbons bound together, hinders the formation of carbon soot. DME can be made directly from synthesis gas, but methanol is a very stable liquid that can be stored and transported without needing a pressure tank. DME, Dimethyl ether H3COCH3, is made from methanol,H3COH, by putting two methanol molecules together and extracting a water molecule.

If all automobiles were able to burn either methanol or gasoline, and methanol were available at the pump at the price it takes to produce it from coal and transport it plus 10% profits for both the producer and seller and taxes, there would be no sale of gasoline because methanol would cost much less per mile of operation of the car. The world has just been caught, by speculators, with few methanol cars and few methanol producers.

Methanol is somewhat easier to make from synthesis gas than DME and can be stored as a liquid in ordinary tanks. A methanol tank truck or railroad tanker is far less dangerous than a DME tanker because after a tank rupture the methanol would sink into the ground as food for bacteria, but the DME would spread as a gas and ignite into as a big fire ball with any spark or small flame. DME ignites far easier than propane and at lower temperatures.

After being shipped as a liquid, methanol can be converted to DME more local to where it is being used and in a very compact clean facility.

The spark ignition system of ordinary cars can and does ignite methanol very well. In the US, methanol was the required fuel on many racetracks for competitions because the fires were more easy to control with water and had far less smoke. The air was cleaner too. The expanding ethanol industry caused a shift to the similar ethanol in recent years.

Spark ignition engines are cheaper to make, are already far more available and are simpler to maintain than DME or diesel engines, so automobiles and small trucks in ordinary use would best use methanol as a fuel. The vast coal fields of China and the US and their waste piles would be a stable source of methanol and avoid wide price swings. All biomass is subject to gasification, just like coal, and can be a source of methanol.

Methanol, once called wood alcohol, was produced originally from waste wood in charcoal kilns. When Henry Ford made cars with wood in them, he made methanol from the waste wood to use to dissolve the car paints by heating wood in kilns and collecting the gasses released, and he sold KingsFORD charcoal.

The energy density of methanol is only about half that of gasoline, but this is partially compensated for by the fact that more efficient engine operation is possible. Larger or more tanks can be fitted easily to cars that need more range. The greater difficulty of producing ethanol from synthesis gas is not worth the cost for the slight increase of energy density and the beverage tax complications.

There are known problems with transporting ethanol in conventional oil pipelines. Methanol may have similar but not identical problems.

In the US and elsewhere the ability to use ethanol as a beverage and the very high taxes on beverage ethanol has, in the past, been a great difficulty for the production of ethanol for chemical and fuel uses. Non beverage ethanol is required to be adulterated with poisons such as gasoline. Methanol is poisonous and is not so taxed. Methanol is no more poisonous than ordinary gasoline.

Methanol attacks some plastics and metals that are sometimes used in gasoline fuel systems. Aluminum is destroyed by methanol. It is not costly to avoid the use of such materials in automobiles. The cost of such changes would be less than the cost of a tankfull of gasoline and is done regularly in Brasil where there is a similar problem with pure ethanol from cane sugar.

Methanol or DME can be made from coal that is so contaminated with minerals that it is not worth shipping. Both methanol and DME are ultra-pure fuels when produced by the modern methods with absolutely no sulphur.

Chemical smog production may be lowered because of the high oxygen level in the fuel. The purity of the fuel may lengthen the life and simplify catalytic converters. There is no ash in either DME or methanol to clog particulate filters or converters as there sometimes is in gasoline or diesel.

The issue of CO2 requires some discussion. It is not clear that the production of methanol from coal and its use in engines will release more CO2 than does gasoline for the number of horse-power-hours delivered to the wheels of the vehicle. There is much gas still just flared at wells because there seems to be no economic use for it and this adds to the actual average CO2 release per barrell of crude oil produced. There is also a known release of CO2 from the fact that an additional 23 gallons of crude are burnt in the production of 100 gallons of useable fuel at the refinery. The transportation of crude oil in tankers, pipes and trucks costs the release of CO2. Fuel delivery trucks and the CO2 releases needed for the operation of fuel sales to customers are similar to the operations with methanol.

It is rarely mentioned that people and animals and plants and micro-organisms breath out CO2. This is also true of volcanos, hot or cold springs and bubbling mud pots. The ultimate cause of greatly increased CO2 levels in the air must be clearly stated and understood to be the unlimited increase of humans permitted by the use of fuel in the industrial revolution of farming. At the same time it must be mentioned that at some time in the past the carbon in the coal deposits and even those in the limestone deposits were once in the atmosphere.

The major disadvantages of high CO2 levels and high air temperatures, are mainly disadvantages to humans; the other live populations of the earth are probably better off with few or without humans at all.

Fermented ethanol, from any source, cannot be considered carbon neutral even if the carbon released in burning it was absorbed from the air, since much fossil fuel is used in fermenting and distilling and distributing it. The use of this fuel is known and is also a part of the wider debate about the energy efficiency of producing ethanol fuel.

If China and the US had had large automotive fleets that burnt methanol and a large, oil company, independant production of fuel methanol in operation, the economies of both countries would be much more resistant to oil price increases, speculative or production related.

It is well known that the production of oil is government limited, even in the US and therefore free market forces cannot work therefore the government must not allow speculation in fuel prices. Limits on off shore production, withholding oil and oilshale leases, permitting oil company conglomeration, filling reserves during high price and high demand periods, requiring lenghthy enviromental reviews and taxing imports of ethanol from Brazil and not oil imports from other countries are just some US examples of The US government interferrence in the energy market.

To this must be added the prohibition of used nuclear fuel rod reprocessing and use, during high raw uranium prices, when such reprocessing is done by England, France, Japan and others. Whilst the US government is forcing the use of ethanol at great expense it is not requiring the installation of new nuclear power plants at much less expense. Nuclear energy can be used in the production of ethanol instead of the coal and natural gas now being used. ..HG..

Goodness Henry,
What a fine summation.
I certainly didn't expect such a detailed response, I hope you enjoyed writing as much I enjoyed reading.
My only query is that you appear to be suggesting that DME is not an appropriate fuel for gasoline (or spark ingnition) engines.
I am quite sure that my readings (? or fancifully optomistic interpretations) suggest that it may in fact hold potential as an acceptable alternative especially when applied to LPG ready transports ? 30% dme 70% lpg cited as a direct substitute for lpg only.
That DME is so often reported as a deisel substitute appears to come about because the best use and efficiency is in a compresion ignition engine.
Although it is reported as requiring special conditions for use and not directly useful in a spark ignition engine.
I have no personal experience with this fuel, and as such find the "LPG" substitute references somewhat confusing.
It is easy to presume that dme has potential for use in standard gasoline engines. However I can find no specific information in this regard.

My question is: Why is DME not applicable in our garden variety gasoline engines?

paste
http://www.aboutdme.org/index.asp?bid=219

"Often described as “synthetic LPG”, DME can be blended with LPG (in a proportion of up to 20%) and used for domestic cooking and heating, without modifications to equipment or distribution networks. Growth in DME’s use for domestic applications is expected to increase sharply as DME use and blending becomes more widespread within the large and growing LPG market – especially in developing countries where portable (bottled) fuel is providing a safer, cleaner and more environmentally benign fuel for cooking and heating. "

paste
http://www.greencarcongress.com/2007/03/researchers_dev.html
"and holds the potential to fuel automobiles that currently run on gasoline."

DME cannot be used in a gasoline engine because the fuel is too light. At atmospheric temperature and pressure DME is a vapor and does not reduce to a liquid until -24.5C, or under slight pressure (this makes it highly volatile, and can blow at any spark). A diesel engine can be modified using specific elastomers for seals, as DME degrades standard engine/tank o-rings and seals.

The difference is between a spark and compression being the ignition source. Diesel engines, unlike gasoline spark engines, rely on compression of the fluid in a piston like motion to provide the energy required to drive.

In a spark ignition engine you want a fuel that does not ignite when compressed and waits for the spark. In a Diesel engine you want a fuel that ignites immediately when it is injected into the compressed air space. These two behaviours are exact opposites.

DME has a great cetane rating, that makes it a bad octane rating. The tendency to self ignite well when injected into a diesel engine means a tendency to ping in a spark ignition engine.

Methanol has a great octane rating (and a corresponding lousy cetane rating) so it works much better in spark ignition engines and not so well in diesel engines.

It is possible to run very high octane fuels, like methanol, in the air intake of a diesel engine and use a small amount of diesel fuel to start the combustion, but this is a difficult process. You must make sure the air intake fuel never pings or auto ignites or it will damage the engine. Very high octane is needed even in a modest compression ratio diesel (it is, after all, designed to cause fuels to self ignite...) so that the timing of the ignition is still controlled by the injected diesel fuel. I have run a Nissan 6 cylinder truck diesel on propane in the air intake (about 1/2 of full fuel) and a Volvo Penta marine diesel on methanol in the air intake. In both cases diesel oil was used for the first 25% of power, then the co-fuel added via a valve into the air intake.

Caterpillar makes a computer controlled system to feed methane into the air intake of standby diesel generators. This assures the fuel mix never enters a regime that would risk damage to the engine.

Methanol is much more corrosive than ethanol. Tendency to corrode light metals decreases as the alcohol gets heavier (to the point where glycol can be used as antifreeze and isopropanol is a common fuel system dryer). It is not too hard to make fuel systems that are resistant to methanol, but it does take some effort. Combustion byproducts are harder on the motor oil. You must use special motor oils to avoid sludge build up. Not hard, but necessary.

In an ideal world, we (China and the US both) would convert our large coal deposits to Fischer Tropsch Diesel and Gasoline for use in our exiting vehicle fleets while we produced new cars that would run on methanol (spark ignited) and DME (compression ignited). Then we could both tell OPEC to go pound sand...

BTW, Methanol is more toxic than gasoline. In particular, even small amounts ingested or even just adsorbed through the skin will cause blindness and deafness by killing the optic and auditory nerves. Don't expect to hand wash parts in methanol and retain vision and hearing for long... While I've handled a fair amount of methanol, it is not something to want to treat lightly.