Posted on 03/27/2006 7:44:35 AM PST by aculeus
Advances in methanol synthesis, coupled with improved fuel cell technology, could make it a viable alternative to gasoline.
Hydrogen has been getting plenty of hype as a potential replacement transportation fuel, for cutting carbon dioxide emissions and reducing dependence on fossil fuels. But methanol would be far better than the more reactive and volatile hydrogen, argues George Olah, a chemist and Nobel laureate, in a new book, Beyond Oil and Gas: The Methanol Economy.
Olah notes that methanol, a clean-burning liquid, would require only minor modifications to existing engines and fuel-delivery infrastructure (see "The Methanol Economy"). And manufacturing it could even make use of carbon dioxide, a source of global warming. Methanol's benefits have long been understood -- now recent advances in methanol synthesis and methanol fuel cells could make this fuel even more attractive.
Currently, about 90 percent of the worldwide production of methanol (CH3OH) is derived from methane (CH4), the main component of natural gas. Today's methods of making methanol have two stages: converting methane into syngas, a mixture of primarily carbon monoxide and hydrogen, and then into methanol. Although these steps have become more efficient over time, the elimination of the syngas step could save money, since it currently accounts for up to 70 percent of the cost of making methanol.
In an effort to eliminate this cost, Olah and his colleagues have explored ways of converting methane directly into methanol. "You take methane and stick in just one oxygen atom," says Olah, director of the Loker Hydrocarbon Research Institute at the University of Southern California (USC). "Easily said, but not so easily done." The problem is that methane is chemically inert, and combines readily with oxygen only at high temperatures. A catalyst helps, but commonly used catalysts themselves work only at 300 degrees Celsius or higher. At these temperatures, most of the methanol produced is oxidized to carbon dioxide and water. Indeed, methanol yields from such reactions can be as low as 2 percent.
Recently discovered lower-temperature catalysts offer better yields, says Roy Periana, associate professor of chemistry at USC. Using a platinum-based catalyst dissolved in concentrated sulfuric acid at 200 degrees Celsius, Periana has achieved a methanol yield of more than 70 percent. He's now looking for less expensive catalysts, and has found some promising ones.
Olah and his colleague Surya Prakash, professor of chemistry at the university, have developed an alternative method for converting methane to methanol, using a halogen such as bromine. In the presence of special catalysts and at less than 250 degrees Celsius, methane reacts with bromine to form methyl bromide (CH3Br) and hydrogen bromide (HBr). Methyl bromide then reacts with water to form methanol. The bromine from the hydrogen bromide can be recovered by reaction with air, and reused.
Making methanol from natural gas -- which still involves fossil fuels and increases carbon dioxide in the atmosphere -- is just the first step, says Olah. Chemists have long known that methanol can be made by combining carbon dioxide and hydrogen. Such a process requires considerable energy, for example, to harvest the hydrogen from water, but this energy could come from carbon-free sources such as nuclear or wind power. The carbon dioxide could be captured from flue gases, and eventually directly from the atmosphere, he says.
In such a system, the carbon dioxide released by burning methanol would be cancelled out by the carbon dioxide captured to make it. So the process would be carbon neutral, and the methanol produced would be a convenient liquid fuel that could replace petroleum-based fuels. If the carbon dioxide comes from air and the hydrogen from water, this method of making methanol would be like fast photosynthesis: "We don't have to wait for plant life to slowly convert excess carbon dioxide into hydrocarbons," Olah says. "We can substitute for Mother Nature."
Olah emphasizes that the methanol produced in this way would not be a new energy source, but simply a convenient way of storing energy. Its advantage over hydrogen would be the ability to use existing engines and infrastructure with only minor modifications.
In many ways, with its low emissions and an octane rating of 100, methanol is already a better fuel for internal combustion engines than gasoline. A methanol engine can run at a higher compression ratio, and is easier to cool. But methanol has some drawbacks: it has lower vapor pressure than gasoline, which makes engines sluggish on cold starts, and it burns with an invisible flame, which could be a safety hazard, since it would be hard for emergency workers to detect in an accident, for example. To mitigate these problems, methanol today is usually blended with 15 percent gasoline to make a fuel mix known as "M85."
Methanol is an even better automotive fuel when used in combination with fuel-cell technology, says Paul Erickson, assistant professor in mechanical engineering at the University of California, Davis. Fuel cells, which convert chemical energy directly into electricity, are more efficient than engines that burn fuel. The hydrogen fuel cell, in particular, has been widely proposed as a clean and efficient alternative to gasoline-powered internal combustion engines. Erickson's laboratory has a functioning hydrogen fuel-cell bus with an onboard reactor that "reforms" methanol to produce hydrogen for its fuel cells. "We completely avoid having to store hydrogen," Erickson says.
Onboard "reforming," however, consumes space and energy. In 1993, Prakash, Olah, and a team at the Jet Propulsion Laboratory in Pasadena, CA, jointly invented a fuel cell that runs directly on a mixture of methanol and water. The cell's positive and negative electrodes are separated by a membrane designed to allow only protons from the methanol to migrate from one electrode to the other. Early versions of this membrane, however, allowed some methanol to get across and react with oxygen at the second electrode, which reduced the voltage of the cell and wasted energy in the form of heat.
In 2001, Prakash and his colleagues developed a new membrane that is both cheaper and more resistant to crossover. With this refinement, the direct methanol fuel cell gives an efficiency of 35 percent, about twice that of an internal combustion engine, but well short of its theoretical efficiency of 97 percent.
The direct methanol fuel cell is currently too expensive to be used in passenger cars. Its high cost comes mainly from the platinum and ruthenium used as catalysts. Prakash and others are developing a variety of approaches to reduce the amount of catalyst needed: making the catalyst more active, increasing its surface area, and using nanoscale methods. When this technology matures, Erickson believes it might replace the hydrogen fuel cell. "An inexpensive, high-power direct methanol fuel cell is the Holy Grail," he says.
Methanol is another good fuel. However, too often, we see promoters and people looking for the next "technological silver bullet" that will cure all of our energy problems.
Once upon a time in the US it was "hydro" (TVA, BPA, Hover Dam, etc.) At another time it was nuclear power. At another time it was central station coal fired power plants. Recently it has been natural gas fired combined cycle combustion turbines. Wind seems to be in vogue again as "the solution."
The point is that different technologies are promising. We should not over promote any of them and we should develop all of them that we can, but not put too much faith on any of them as "the single solution to our future."
Dear Robert357,
"...but not put too much faith on any of them as 'the single solution to our future.'"
Great point. However, mostly what I see here at FR and at other sites I see these questions discussed is that the naysayers of a given technology are usually the folks characterizing the technology as a potential "silver bullet." And then, after creating that straw man, they knock it down.
Thus, biodiesel from waste products, ethanol production, oil from ANWR, oil from shale, off-shore oil, expanded nuclear, etc., are all considered unrealistic answers to the problem of energy production because no one of these solutions appears to be the single answer.
However, if each of these potential sources can add modestly to our overall domestic energy production, we would greatly expand overall energy production, and be able, if we decided as a country, to reduce reliance on foreign energy imports.
Folks will point out that these alternatives are costly, certainly more costly than the production costs of Arab or Venezuelan oil. However, that's only when we're looking at the direct costs, and ignoring the externalities.
Who here thinks that the Middle East would play such an important role in our foreign policy if these countries didn't supply crucial world energy supplies? Who here thinks that Saddam Hussein would have ever become so powerful and dangerous without critical oil reserves?
sitetest
As long as the windmills are kept out of the view of wealthy leftists' residences, and far away from birds.
One thing I noticed was the lack of any numbers as to the amount of land that would be required to grow the organic material, usually corn, as the basis for the fuel. It may look like a boon for the corn people, but i wonder just how much of the mid west would have too be put to corn to replace the gasoline used just in the US.
So methanol is an element now?
What's its symbol - Mth?
You sure you're not thinking of ethanol?
Methanol is a tad too volatile, and also poisonous. One does not need to drink it - inhaling the vapors will do over prolonged exposure.
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Oh... you mean just like gasoline.
A bit worse. Methanol is both more toxic and more volatile [i.e. there are more vapors].
bttt
Methanol is very soluble in water. If it starts to be used in motor fuel it WILL turn up in the ground water. MTBE, a substance used in small percentages and which isn't extremely soluble in water, has already been causing problems in people's water wells on a fairly large scale.
Put windmills on the Mall in Washington DC. . .Congress will be able to power the entire CONTINENT for decades to come. . . (evil grin)
windmills = aviary cuisinarts
I regularly burn methanol..... best fuel for an accohol lamp.
One of my relatives used to be a physician-narcologist [treating alcoholics] in Vitebsk [Belarus]. Once he was called to head an emergency medical response team - in an industrial setting the workers found a 55 gal [200 liters]drum labeled "methyl alcohol" [i.e. methanol]. The word "alcohol" they understood, the word "methyl" they did not, skull/crossbones they did not believe - and so they [several hundred of them] drank it. Well, if I remember right, my uncle's team managed to save about a hundred of them - but they got blind.
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