Di-methyl-ether (DME) is a fuel that I have been talking about since at least 2006. I have blogged about it, and I have classified it in several of my presentations as a “Sustainable Contender” (including in a slide at last year’s ASPO conference). I want to use this post to explore DME in a little more detail, and explain why I think you should keep an eye on it as an attractive renewable replacement for diesel.
DME is a pretty simple compound. Methane, the least complex hydrocarbon, has the chemical formula CH4. That is one carbon atom bonded to four hydrogen atoms. When methane is burned – which is to say reacted with oxygen – it produces carbon dioxide (CO2) and water (H20).
DME can be thought of as a couple of methane molecules with an oxygen separating them. It looks like this: CH3 – O – CH3. This is an ether; in fact the simplest ether (characterized by the oxygen separating two hydrocarbon groups). Note that each methane (methyl) group is missing one hydrogen, which allows it to form the bond with oxygen. But when DME is burned, you still end up with carbon dioxide and water.
DME is produced from methanol, the simplest (and cheapest) alcohol. The current price for methanol as listed by Methanex is $1.10/gal, compared to a national average rack price of $2.26/gallon for ethanol and a national average spot price of $1.83/gallon for gasoline.
Methanol works fine as a transportation fuel, but has some disadvantages. While methanol is cheaper to produce than ethanol, the energy content per gallon is even lower than for ethanol (and methanol is more toxic). Ethanol has about 2/3rds of the energy content of gasoline, but methanol contains only half the energy content of gasoline. As a transportation fuel, this is a disadvantage (but not a knockout) because it limits the range of your car.
As a fuel, DME can be used in either a gasoline or a diesel engine. That makes the potential market huge. DME is a gas at room temperature, but compresses to a liquid under mild pressures. It is currently used as a propellant in many consumer products, and is classified as non-toxic and non-carcinogenic. (Granted that if you stand around in a room filled with nothing but DME, you will die due to oxygen deprivation. The same is also true of nitrogen, which makes up 79% of our atmosphere).
DME is completely miscible with LPG, and can be used as a supplement/replacement in either transportation or heating applications. When combusted, DME burns very cleanly. There are no associated sulfur or particulate emissions (even in a diesel engine).
DME can be produced from biomass, coal, natural gas, or essentially any source of carbon. Unlike many ‘next generation’ biofuels, production from biomass is a straightforward route and not especially complex. You gasify biomass to produce syngas, react syngas to produce methanol, and then dehydrate the methanol. Each of these steps takes place every day at large scale at chemical companies around the world.
There are some specific disadvantages from DME, but this is true for just about any fuel. First, the fact that it is a gas at room temperature means that if there is a leak, it can form an explosive mixture in the air. The same is true for natural gas or LPG. Second, the energy density of the fuel is lower than for gasoline or diesel. The volumetric energy density lies between that of ethanol and methanol.
So why aren’t we using it in North America? Like many other fuels, it is a chicken and egg problem. We don’t have the infrastructure in place in the U.S. Some vehicle modifications would be required to accommodate it as well. But these are not insurmountable problems, as the continuing roll-out of E85 vehicles and service stations has shown.
The Chinese have embraced DME for years, and are increasing their DME capacity. This allows them to convert their coal into something much more desirable for them – transportation fuel.
The Swedes are also at the forefront of rolling out DME. The Swedish company Chemrec has been converting pulp mills into biorefineries that produce DME. Volvo has announced that they are conducting studies on the performance of DME in 14 of their heavy trucks over the next two years. (Here is another story on that at Green Car Congress).
In North America, I know several people or groups who have expressed interest in, or are dabbling with DME. My expectation has been that at some point there will be an entry into the market here, but it will be slow due to the aforementioned lack of infrastructure. What prompted me to write this essay was I spotted a story yesterday about a Canadian company that is going to give it a shot:
Dimethyl ether: The unknown fuel that’s gaining fame
A clean fuel that’s already gaining traction in Asia could be getting a toehold in Canada, just in time to help northwest B.C.’s hard-hit forest industry. Dimethyl ether, or DME, is almost unknown in North America but may soon get a big boost here from new tough emission standards coming to the U.S.
DME is a mixture of hydrogen and carbon monoxide that can be produced from biomass, natural gas or coal. It is now used as a propellant in aerosol spray cans because it is non-toxic and breaks down. But DME also has the potential to replace diesel fuel because it produces 95 per cent fewer greenhouse gases, no soot, low levels of nitrogen oxide and no sulphur dioxide.
Calgary-based GV Energy is proposing to build a biorefinery to produce DME in Terrace, B.C.
While some of those details are slightly inaccurate, the article is a good read on how DME can fit into the fuel mix and add jobs in an area with the right resource base. Especially interesting to me is to view the comments from readers. I find it amazing at times the emotional attachment some people have to trees. I can understand opposition to the conversion of forest to pasture or agricultural land. I can understand the opposition to clear-cutting and not replanting. But it seems that to some people, cutting down a tree is just wrong. Period. This coming from people who are living in houses made from wood.
If we use managed forestry to produce DME, then that has the potential to be an improvement over the status quo. Like anything else, there is a right way and a wrong way. But just because a wrong way exists doesn’t mean that you don’t try at all. We (my company) are not going stop trying to responsibly manage and use forest assets just because some aren’t doing so. We will just continue to do things in the most sustainable way we can, and hope that the proper incentives are in place to make sure others do so as well.
But I digress a bit. To learn more about DME, see this presentation put together by Europe’s BioDME project. Note especially the slide that shows the land usage efficiency of DME relative to competing fuels.
The market for DME is bound to continue growing due to its versatility as a fuel and because it can be produced relatively easily from a wide variety of starting materials. The question is whether North America will continue to watch that growth occur in Europe and China.
Update: I have received a note that another BC company is also working on DME: Blue Fuel Energy.
$1.10 a gallon would compete favorably with gasoline,provided it wasn't taxed at the pump. What are the necessary modifications,and why haven't we made them? We've got 30% of the worlds coal. If we could get off oil imports this easily,we're fools not to go for it.
We're probably not going to do wide-scale gasification of coal, Maury, for several reasons. And, when you get to gasification of biomass, methanol will be, I think, almost as expensive as ethanol, but with a more corrosive product, with 30% less energy.
Isn't the problem with DME, at present, trying to get the cost down, RR?
Is the reason for looking at this the fact that gasification of biomass is going to yield quite a lot of methanol; and they're looking for something to do with it rather than burn it, directly?
Here's why we aren't doing it…
DME will always be much more expensive than methanol per unit energy. Some advocates believe the minimum energy losses in conversion of methanol to DME can be as low as 5%, but 15% is probably typical.
Because of DME’s low energy density, distribution costs will be at least 30% higher than for propane, for which distribution costs to consumers (refilling barbeque grill-sized tanks, 4.73 gal) are typically 20 times those of gasoline. Hence, a reasonable estimate (from the combination of conversion and distribution costs) is that DME would likely cost consumers three times as much per unit energy as methanol, at least until DME-vehicles are in wide usage, which would take more than three decades even with favorable economics.
What about end use in small engines? Small diesel engines have demonstrated efficiency over 45%, gasoline engines can achieve 35%, and high-compression advanced E85 engines should ultimately be able to exceed 45% efficiency. The best thus far from DME engines is about 30% and it’s not clear how much room for improvement there is.
DME from fossil-derived methanol doesn’t reduce CO2 emissions. It increases them compared to convention diesel – mostly because of the huge CO2 releases from the plants producing the methanol and because of the reduced efficiency of DME engines.
It is true that methanol from renewable H2 (as from water electrolysis using wind energy) would allow the production of carbon-neutral methanol and hence carbon-neutral DME. However, it’s hard to believe there will be much investment in production of carbon-neutral methanol (~$1/kg) as long as fossil-derived methanol is less than one-third as expensive. The price disadvantage for green DME will be enormous.
http://tinyurl.com/yhjyswg
"DME also has the potential to replace diesel fuel because it produces 95 per cent fewer greenhouse gases"
Is this an accurate statement? In comparison, replacement of Diesel with Natural Gas reduces GHG emissions by ~30%…
That makes at least three dimethyl compounds that could be useful fuels and could start from biomass. The other two I know of are 2,5-dimethylfuran and 2,3-dimethylbutane (I don't know if the other isomers would be useful and could be made easily). It makes me wonder if any other dimethyl compounds would be good candidates; I suppose you could say propane was one, if you think of it as dimethylmethane. You can get that by decarboxylating butyric acid.
I often find myself in the middle dodging stones thrown from both sides.
A collection of trees is not the definition of an ecosystem. Many treehuggers don't get this point and neither do many logging companies, not that they should since profit has little to do with intact ecosystems.
Woodland park here in Seattle is a large collection of trees yet it is as ecologically impoverished as my backyard, maybe more so.
I own forest property. I purchased it as clear cut and have watched the trees maturing over the years. Biological diversity is dropping as they command more and more of the sun's energy for themselves.
Many species that could be found on the property are now absent but can be found in other nearby regrowing clear cuts.
Clear cuts mixed with maturing forests and old growth make for a robust and diverse ecosystem. A clear cut is often much preferable to a forest fire.
A monoculture tree farm is less environmentally stressful than say a corn crop because it won't require pesticides, disrupt soil, need fertilizers or create all of the attendant runoff that is causing dead zones, but if a tree farm replaces an intact forest ecosystem, it is worse than a corn field ecologically although for different reasons.
Is this an accurate statement? In comparison, replacement of Diesel with Natural Gas reduces GHG emissions by ~30%…
No, it isn't. That was one of the statements I was referring to when I wrote "While some of those details are slightly inaccurate,…"
I think it is due to the way they calculated it, but it can't possibly be accurate.
RR
Isn't the problem with DME, at present, trying to get the cost down, RR?
That is a problem, but not the main problem. We are already using fuels whose real cost is as great or greater than DMEs. The real problem I think is that we just don't know enough about it. I think if the Volvo experiment turns out favorably, we will have a very good reference point, and at a minimum DME will make a good case for being a renewable diesel substitute.
RR
Here's why we aren't doing it…
That's not why we aren't doing it. If you think that, read through the section on biofuels. You could then conclude "Here's why we aren't doing biofuels." But of course we are doing biofuels.
DME will always be much more expensive than methanol per unit energy.
Maury, I am aware of that link, but disagree with the assessment. I agree that DME will be more expensive than methanol (which I definitely like as a fuel) because it is made from methanol (there are other pathways, but I think they are more expensive). But I don't think some of the author's comments hold. (The site is pretty informative, by the way. I have visited it several times).
Take the comment on energy density. The energy density is close to that of ethanol – but DME can be pipelined through existing pipes. Do you believe that ethanol's distribution costs are 30% higher than for gasoline? That is the necessary conclusion based on the author's logic of energy density, but I bet you don't believe that.
I agree that from a cost/efficiency point of view, methanol would be better in internal combustion engines. But methanol can't be run straight in diesel engines. Conversion to DME also gets around the toxicity issues that many have raised with methanol (but which I feel are overrated, because methanol is quickly metabolized by bugs if it is spilled).
RR
Maury/Rufus – I love DME as a fuel. Compared to gasoline or biodiesel, it is extremely easy to make either from abundant supplies of coal or biomass (gasification) or natural gas. DME requires less hydrogen shift reaction and only adds two fixed bed reactors to the gasification unit.
The problem with DME is the same as E85. Vehicles aren't built to use it. It is a chicken and egg thing. Require automakers to build flex fuel vehicles and then let all fuels (gasoline, diesel, methanol, ethanol, DME) compete for market share.
BTW – there is a DME advocacy group About DME .
I looked at DME as an alterntative to importing LNG for power generation.
Compared to gasoline or biodiesel, it is extremely easy to make either from abundant supplies of coal or biomass (gasification) or natural gas. DME requires less hydrogen shift reaction and only adds two fixed bed reactors to the gasification unit.
King, does that route bypass the need to make methanol? Or is methanol then a reaction intermediate? I can see cases where DME might not be much more expensive to produce than methanol, provided you aren't using pure methanol as feedstock.
I was looking for costs yesterday to compare to methanol. Do you know a good source?
Cheers, Robert
From the post: "DME can be used in either an internal combustion engine or a diesel"
As one person who often makes silly mistakes to another, Robert, let me point out the obvious flaw — a diesel engine IS an internal combustion engine.
You meant either a spark ignition or compression ignition engine.
It is true, that many fuels or transportation methods are more expensive than gasoline, especially in the good ol' days, when oil was cheap.
That does not mean doom, or even that living standards have to go down.
We know how to produce cars that get much more mpgs than before, or even PHEVs. That easily compensates for the higher fuel cost.
We can use ethanol, methanol (really not very poisonous) or DME in radically smaller quantities than oil, especially if our fleet is largely PHEVs or CNG.
The positive upshot of all this is we import less oil, and produce domestically. I would rather give my money to some Pennsylvania gas boys than the usual oil thug states.
The second positive upshot is that all these fuels appear to burn more cleanly than gasoline.
Really, the future looks bright, and cleaner.
If most cars become PHEVs, then even quieter.
BTW, there was another glowing review in the LA Times today about Audi's all-e luxury sportster, coming out next year. Again, the reviewer says the new all-e cars just blow the doors off of ICEs when it comes to acceleration.
Lithium battery advancements continue apace. We are getting close, so close to commercialization of lithium battery cars–and we can make methanol or DME from NG or coal.
I just do not see a doom scenario here.
You meant either a spark ignition or compression ignition engine.
Thanks, fixed. I was thinking SIE when I wrote it, but I put that up pretty late last night. I often find little errors like that when I put things up late. I would rather put things up early after reviewing them one last time, but the time difference in Hawaii means that when I wake up, everyone on the mainland is usually already at work. So now I find myself posting more things late at night.
RR
"I looked at DME as an alterntative to importing LNG for power generation."
Have you checked out nukes?
Russ F
Nice post on timber management practices in the (semi-arid?) until you got to root blame analysis with “causing dead zones”. I know that was not taught at your alma mater. There are many ways of doing things better, I do not see the logic of making up arguments against better. My better is better than your better.
Seattle has turned into a cesspool with big freeways. One of the pastimes of 'greens' in Seattle is to get into their cars and go protest how their timber, food, and electricity is produced. Can you image the mayor of Richland traveling to Seattle and demanding Boeing stop building airplanes.
Since Russ seem interested in doing things better he should check out the management of his sewage sludge and trash. Seattle put it in a truck and sends it 200 miles across the mountains. The clever people there grow food and produce energy with it.
Isn't DME an intermediate when going from methanol to gasoline?
Robert,
Great to see you bring up this subject.
The great argument for DME is that it is a replacement for BOTH gasoline and diesel with proven, current technology to back it up : LPG conversion for gasoline and direct fuel injection for diesel.
This point needs to be repeated over and over, repeated over and over, repeated over and over 🙂
By the way, what your opinion of one-step synthesis like the NKK process ?
http://www.jfe-steel.co.jp/archives/en/nkk_giho/85/04.html
Coal to liquid fuel is our ace-in-the-hole when/if the sierra hits the fan. If we really put our mind to it, within five years we could transition to either for our fleet of autos and trucks. And in the future, cars can even be powered by methanol fuel cells — a technology that already exists. (RR – Do you know anything about how DME works in fuel cells?)
Methanol or DME will work. And the toxicity of methanol isn't the problem people like to always say.
As I've said before, every new car already comes with a reservoir methanol under the hood — it's what windshield washer fluid s made of, and almost everyone who has a garage already has a jug of methanol sitting on a shelf or on the floor.
Beyond Oil and Gas: The Methanol Economy
Like hydrogen, both methanol and DME are only energy carriers, but both methanol and DME offer one huge advantage over hydrogen — both are much easier to handle and present far less daunting obstacles than hydrogen.
So you turn your DME into gasoline using the Mobile process and sell that. When people are ready to buy the cheaper DME, then you stop making so much gasoline and sell the DME.
The only trick is to make the xTL MeOH to gasoline as cheap as the petroleum gasoline. Or make the petroleum gasoline as expensive as the xTL.
One of the reasons I like the idea of using external combustion engines as opposed to ICEs is that it would take away the issue of which fuel for which engine.
Maybe these guys should use DME as they try to go for a new steam powered land speed record.
Does anyone know what the efficiency is of producing DME from electricity?
"Maury, I am aware of that link, but disagree with the assessment"
Yeah,I thought it was overly pessimistic too Robert. We have domestic energy supplies that can displace foreign crude imports. Congress should get off its ass and help it happen. For all the yap about flexfuel vehicles,only 3% of American cars can burn E85. LNG would be readily available for everyone if the US fleet was equipped for it. So what is Congress waiting for?
Witricity will enable EV's without the expensive batteries someday. That'll probably be the nail in the coffin for ICE's. Until then,we can produce our liquid fuel domestically. If we really want to.
Today I had a discussion with a man from Florida about DME. We chatted about it nearly 13 hours before I read this post by RR and the following 25 comments.
Both of us knew that DME was a compressed, gaseous ether which burned cleaner because of the intrinsic oxygen content per molecule, yet it carries less BTU's of energy density than does C3 hydrocarbon propane.
Neither one of us felt that bottled, compressed gasses had any real place in propelling freeway traffic simply for safety reasons. I don't share Benny's nor T-Boone's enthusiasm for compressed natural gas in vehicles either.
RR stated that DME becomes liquid (like propane or butane) at moderate pressures. What is a moderate pressure? Just curious. Thanks.
Cliff
King, does that route bypass the need to make methanol? Or is methanol then a reaction intermediate? I can see cases where DME might not be much more expensive to produce than methanol, provided you aren't using pure methanol as feedstock.
I was looking for costs yesterday to compare to methanol. Do you know a good source?
Yes, there are at least two companies that I know of who have direct conversion of syngas to DME processes. I haven't seen costs on large commercial sized DME plants, other than internal studies. The plants that have been built so far produce DME for the aerosol or chemical market in small quantities.
Amoco was seriously looking into it before they were bought up by BP. They would be the experts.
Once you have Methanol, or DME, is int it relativley simple to synthesize higher order hydrocarbons? I would think that lower fuel volatility would be a good thing.
Once you have Methanol, or DME, is int it relativley simple to synthesize higher order hydrocarbons? I would think that lower fuel volatility would be a good thing.
Well thought-out comment Benjamin.
I don't see how any competitor will get a toe hold with the corn ethanol lobby pulling the puppet strings. The tariff on ethanol imports is just one example of how to do it. Lobbying to remove government support for a competitor is another way to do it and on and on.
Although I cringe when I hear extremists using the term, this control of politics by industry is brushing up against the definition of fascism, be it big oil or big biofuel.
You could make biofuel DME and fill those small camping canisters. (Like Coleman propane cylinders) Then you could sell them to hippi hikers as a carbon neutral camping fuel.
King,
Can you please identify the two companies you noted that are currently producing DME from syngas.
Thanks,
Brian
Fat Man – yes, you can make longer chain hydrocarbons from methanol. ExxonMobil has a methanol to gasoline process (MTG). The issue is capital costs. MTG and Fischer Tropsch liquid processes produce an intermediate fuel that is something like diesel or gasoline but has to be further processed to meet one or more fuel specifications. (reduce olefin content, raise octane or cetane index, etc.)
Pure component fuels like ethanol, methanol, and DME don't require these added steps.
Haldor Topsoe is working on syngas to DME direct conversion .
So is Lurgi
Toyo Engineering has an
indirect method that heat integrates the methanol and DME synthesis steps.
Direct conversion saves you the methanol distillation column and the DME reactor.
RR stated that DME becomes liquid (like propane or butane) at moderate pressures. What is a moderate pressure? Just curious.
50-100 psig.
RR