Viewing 15 posts - 91 through 105 (of 107 total)
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  • #5436
    AvatarBrian H
    Member

    JimmyT wrote: The subject of using methanol as a motor fuel is suprisingly complex.

    Point 1: The reaction of making methanol out of Carbon monoxide and Hydrogen is exothermic and reversible. What that means practically is that the methanol contains significantly less energy than the Carbon monoxide and hydrogen that produce it. However it is much easier to store than the component gases. This effect can be used to advantage my adding a “reformer” to each auto. The reformer would use waste engine heat to break down the methanol into the two gases used to produce it which once again will have much more energy than the origanal methanol. Result: an increase of efficiency of about 30%, if I remember my chemistry correctly.

    Point 2: Methanol is highly toxic. Even it’s vapors are toxic, and the liquid methanol is readily absorbed thru the skin. The effect of exposure, even low level exposure repeatedly, is irreversible blindness. This material is far too toxic to be used in do it yourself fuel centers. So we would be back to attendants filling your car. And despite precautions, many of them will go blind. So an additional “cost” of widely adopting this fuel will be an army of blind ex-fuel attendants.

    This is not meant to be an argument against using methanol as a fuel. It is just to point out a couple of unmentioned considerations.

    Since the “waste heat” would be coming from the combustion of the gasses and/or methanol, there would be only a limited benefit, I believe. On account of the laws of thermodynamics and all. :cheese:

    #5437
    AvatarPete Keech
    Member

    Methanol toxicity is not as high as you might think. Ingestion is a minor problem, but not really worse than gasoline or diesel:
    http://hawaii.gov/dbedt/ert/new-fuel/files/afrw/afrw-10.pdf

    mls for (possible) death:
    gasoline 115-470
    diesel 63
    MeOH 60-240

    MeOH also has antidotes (ethanol – amusingly, Fomepizole), unlike gasoline in the case of acute poisoning, so treatment could mitigate some exposure issues.

    There is also the lower volatility vs. gasoline, so that is less of a problem (to reach 400 mm Hg at 1 atm, gasoline needs <40 °C vs. MeOH needs °50 C), so overall exposure is lower through inhalation. Not to mention the lower flashpoint & other safety advantages it has over gasoline (environmentally much more benign than petroleum products). You could easily have self dispensation, or dispensation by minimally trained attendants (give them gloves & eye protection). Current propane handling is actually more dangerous, and should have those safety equipment & often don't. Really gasoline should as well, but we've historically decided against that…

    As I indicated, EtOH may be a better bet long term (lower toxicity, lower environmental impact), but maybe not – that test will come.

    As for “exothermic”… What do you mean? This is CO2 not CO, since CO2 is the problem greenhouse gas, and readily available vs. CO (corrosive, poisonous). Invoking anything with CO in the mechanism allows for the most problematic chemical on our list since gases are so much more difficult to contain. Let’s avoid that.

    The reaction to make methanol:
    CO2 + 2H2 –> CH3OH
    At 25°C, that has +delta G of 240 J/mol (i.e. you add some form of excess energy), and + delta H of 160 J/mol (i.e. you add this much heat energy to keep temperature constant). That makes it endothermic not exothermic. This is also some of the energy losses you can assume in the conversion process (for which I estimate a low 50% on my previous post), but playing with the temperature (or more likely) pressure could minimize these – high pressure favours CH3OH. That’s why I suggest a target of 90% for the conversion once people say electricity is cheap…

    Because the whole system is closed (CO2 & H2 out of atmosphere/ water & put back in at the end), the tracking of energy is easy. It all comes from the generation of the electricity, which is eventually converted to heat by the proposed mechanisms, and you can ignore any individual process along the way. Comparatively, getting fuel out of the ground has an enormous heat energy output (before you even burn it yourself), and the amplification effect of the additional greenhouse gases makes it that much worse.

    Finally, this discussion can only really be applied to existing infrastructure, as new infrastructure will undoubtably become electrically based over the next generation if electrical energy is so cheap. Virtually all energy (and nuclear) research funds will go into electrical storage/batteries, and migrate away from liquid fuels (despite their very high energy densities). Cheap/abundant materials will abound, like the aluminum-air battery (very high energy storage per weight, but inefficient electrically, but who cares if electricity is cheap). Aluminum is also cheap, and air is free.
    Let’s consider hydrogen within today’s technology: If we could generate cheap hydrogen (amusingly the only hope for the so-called hydrogen economy) it could be cheaply stored (via compression, as liquids, or as solids, as hydrides, etc, etc) using our cheap electricity, and the energy density would be high enough to scrap liquid fuels entirely, as of today.

    #5438
    AvatarBrian H
    Member

    Pete;
    Great reply, fun to read!
    But waste heat is hardly a serious problem. And, as Climategate is now airing for one and all, neither is CO2. I refer you to http://arxiv.org/pdf/0707.1161v4 again, and my excerpt:

    In [the] case of partial differential equations[,] more than the equations themselves[,] the boundary conditions determine the solutions. There are so many different transfer phenomena, radiative transfer, heat transfer, momentum transfer, mass transfer, energy transfer, etc. and many types of interfaces, static or moving, between solids, fluids, gases, plasmas, etc. for which there does not exist an applicable theory, such [meaning] that one even cannot write down the boundary conditions [176, 177].
    In the “approximated” discretized equations artificial unphysical boundary conditions are introduced, in order to prevent running the system into unphysical [non-physics] states. Such a “calculation”, which yields an arbitrary result, is no calculation [at all] in the sense of physics, and hence, in the sense of science. There is no reason to believe that global climatologists do not know these fundamental scientific facts. Nevertheless, in their summaries for policymakers, global climatologists claim that they can compute the influence of carbon dioxide on the climates [of planets]. [ed. suggestions in braces [] since authors are native German speakers.]

    As far as liquid fuel usage, I agree that there would be a rather steep decline in the profitability of its manufacture and distribution over a decade or so, such that its use would become problematic, and support for that massive infrastructure would steadily degrade. The same would likely apply to hydrogen, though, as the storage and transport costs and issues are never going to be less than challenging and comparatively expensive. I find it hard to imagine there could ever be a sustained base level of demand adequate to justify its deployment.

    But we’re kind of whistling in the dark. With so much at stake, the engineering focus and advances that will take place will likely beggar present imagination.

    #5439
    AvatarJimmyT
    Participant

    Brian H wrote:

    The subject of using methanol as a motor fuel is suprisingly complex.

    Point 1: The reaction of making methanol out of Carbon monoxide and Hydrogen is exothermic and reversible. What that means practically is that the methanol contains significantly less energy than the Carbon monoxide and hydrogen that produce it. However it is much easier to store than the component gases. This effect can be used to advantage my adding a “reformer” to each auto. The reformer would use waste engine heat to break down the methanol into the two gases used to produce it which once again will have much more energy than the origanal methanol. Result: an increase of efficiency of about 30%, if I remember my chemistry correctly.

    Point 2: Methanol is highly toxic. Even it’s vapors are toxic, and the liquid methanol is readily absorbed thru the skin. The effect of exposure, even low level exposure repeatedly, is irreversible blindness. This material is far too toxic to be used in do it yourself fuel centers. So we would be back to attendants filling your car. And despite precautions, many of them will go blind. So an additional “cost” of widely adopting this fuel will be an army of blind ex-fuel attendants.

    This is not meant to be an argument against using methanol as a fuel. It is just to point out a couple of unmentioned considerations.

    Since the “waste heat” would be coming from the combustion of the gasses and/or methanol, there would be only a limited benefit, I believe. On account of the laws of thermodynamics and all. :cheese:

    No, waste heat would come from engine exhaust gas (waste Heat).

    #5440
    AvatarJimmyT
    Participant

    Pete Keech wrote: Methanol toxicity is not as high as you might think. Ingestion is a minor problem, but not really worse than gasoline or diesel:
    http://hawaii.gov/dbedt/ert/new-fuel/files/afrw/afrw-10.pdf

    mls for (possible) death:
    gasoline 115-470
    diesel 63
    MeOH 60-240

    MeOH also has antidotes (ethanol – amusingly, Fomepizole), unlike gasoline in the case of acute poisoning, so treatment could mitigate some exposure issues.

    There is also the lower volatility vs. gasoline, so that is less of a problem (to reach 400 mm Hg at 1 atm, gasoline needs <40 °C vs. MeOH needs °50 C), so overall exposure is lower through inhalation. Not to mention the lower flashpoint & other safety advantages it has over gasoline (environmentally much more benign than petroleum products). You could easily have self dispensation, or dispensation by minimally trained attendants (give them gloves & eye protection). Current propane handling is actually more dangerous, and should have those safety equipment & often don't. Really gasoline should as well, but we've historically decided against that…

    As I indicated, EtOH may be a better bet long term (lower toxicity, lower environmental impact), but maybe not – that test will come.

    As for “exothermic”… What do you mean? This is CO2 not CO, since CO2 is the problem greenhouse gas, and readily available vs. CO (corrosive, poisonous). Invoking anything with CO in the mechanism allows for the most problematic chemical on our list since gases are so much more difficult to contain. Let’s avoid that.

    The reaction to make methanol:
    CO2 + 2 –> CH3OH
    At 25°C, that has +delta G of 240 J/mol (i.e. you add some form of excess energy), and + delta H of 160 J/mol (i.e. you add this much heat energy to keep temperature constant). That makes it endothermic not exothermic. This is also some of the energy losses you can assume in the conversion process (for which I estimate a low 50% on my previous post), but playing with the temperature (or more likely) pressure could minimize these – high pressure favours CH3OH. That’s why I suggest a target of 90% for the conversion once people say electricity is cheap…

    Because the whole system is closed (CO2 & H2 out of atmosphere/ water & put back in at the end), the tracking of energy is easy. It all comes from the generation of the electricity, which is eventually converted to heat by the proposed mechanisms, and you can ignore any individual process along the way. Comparatively, getting fuel out of the ground has an enormous heat energy output (before you even burn it yourself), and the amplification effect of the additional greenhouse gases makes it that much worse.

    Finally, this discussion can only really be applied to existing infrastructure, as new infrastructure will undoubtably become electrically based over the next generation if electrical energy is so cheap. Virtually all energy (and nuclear) research funds will go into electrical storage/batteries, and migrate away from liquid fuels (despite their very high energy densities). Cheap/abundant materials will abound, like the aluminum-air battery (very high energy storage per weight, but inefficient electrically, but who cares if electricity is cheap). Aluminum is also cheap, and air is free.
    Let’s consider hydrogen within today’s technology: If we could generate cheap hydrogen (amusingly the only hope for the so-called hydrogen economy) it could be cheaply stored (via compression, as liquids, or as solids, as hydrides, etc, etc) using our cheap electricity, and the energy density would be high enough to scrap liquid fuels entirely, as of today.

    I wasn’t commenting on your proposed synthesis method. I was trying to point out a way to make it’s use more effecient. Greater range/tankfull. That sort of thing.

    As to toxicity. The other petroleum distillates’ toxicity tends to not be cumulative. And I wasn’t talking about death, but blindness.

    Doesn’t the synthesis method you propose really go something like this:

    CO2 + H2 -> CO + H2O

    CO + 2 H2 -> CH3OH ?

    Where is the water in your energy ballance? Carbon monoxide IS produced, as an intermediate.

    And when you are talking about fuel useage you have to include the heat of vaporization. You are starting with liquid methanol, right?

    #5441
    AvatarBrian H
    Member

    No waste heat would come from engine exhaust gas (waste Heat).

    All the heat, including the waste, comes from the combustion process. You might reduce the lost energy burden slightly, but concentrating the heat adequately is also lossy. No free lunch, is all I mean. But transforming as much of the chemical energy into motion as possible is the goal, and cutting tailpipe heat loss is somewhat helpful.

    #5442
    AvatarJimmyT
    Participant

    Sorry Brian, I left out the all important comma in my first draft. Changes the whole meaning of my sentence, doesn’t it?

    This really is one of those rare cases where you can get something for nothing. You get a fuel with a higher energy content merely by capturing some of the waste heat in the exhaust.

    This really does work. I learned this trick in a synthetic fuels class which I took at Ohio State.

    #5443
    AvatarJimmyT
    Participant

    Pete, you are right. Ethanol does prevent methanol’s toxic effects. (Prevents the formation of formic acid by saturating the enzyme alcohol dehydrogenase) But you have to get the alcohol fairly soon after exposure. And with chronic exposure this is a problem.

    So let’s hire exclusively alcoholics as our fuel attendants. And make sure that they are drunk all the time in the performance of their duties. Win win.

    #5445
    AvatarRematog
    Member

    Just off the cuff, but as I recall, Germany used methanol injection to boost horsepower of fighter engines in World War II. They did this as the synthetic fuels they were using were very low octane (roughly 80). A major drawback was that the methanol was very hard on the engine and would destroy it in only a couple of hours of operation. This was acceptable in a combat situation, but… as a long term fuel, would not methanol cause major problems with engine reliability and life… I know I now expect a car I buy to last 125,000 to 150,000 miles.

    #5464
    AvatarTransmute
    Member

    Methanol is certainly a good option, its makes for much easier FT synthesis of even hydrogenated syngas, but methanol is not as flexible as fuel and feedstock as oil is, and transporting methanol is not as oil pipes would need to be replaced to transport such a highly oxygenated fuel.

    As for you global warming deniers; this thread has nothing to do about global warming, unless you want to deny peak oil as well.

    #5467
    AvatarBrian H
    Member

    Transmute wrote: Methanol is certainly a good option, its makes for much easier FT synthesis of even hydrogenated syngas, but methanol is not as flexible as fuel and feedstock as oil is, and transporting methanol is not as oil pipes would need to be replaced to transport such a highly oxygenated fuel.

    As for you global warming deniers; this thread has nothing to do about global warming, unless you want to deny peak oil as well.

    a) Heard about Climategate yet?
    b) FF will delay peak oil indefinitely, as its use will plummet. So it’s on the way to being an irrelevancy.

    #5576
    AvatarTransmute
    Member

    Brian H wrote: [
    a) Heard about Climategate yet?

    yes, yet the scientific evidence for anthropogenic climate change is not limited to IPCC, for example where in this argument is the IPCC data cited? Your argument is equivalent to saying the sky is not blue because the filters on a specific camera are suspect.

    b) FF will delay peak oil indefinitely, as its use will plummet. So it’s on the way to being an irrelevancy.

    Assuming FF is achieved and soon.

    #5578
    AvatarBrian H
    Member

    Transmute wrote:

    [
    a) Heard about Climategate yet?

    yes, yet the scientific evidence for anthropogenic climate change is not limited to IPCC, for example where in this argument is the IPCC data cited? Your argument is equivalent to saying the sky is not blue because the filters on a specific camera are suspect.

    b) FF will delay peak oil indefinitely, as its use will plummet. So it’s on the way to being an irrelevancy.

    Assuming FF is achieved and soon.
    That site is another shill site for the money-chasers (and make no mistake, billions have been and are being spent to try and push the panic button and keep the governments funding everything in sight).
    Try this: http://arxiv.org/pdf/0707.1161v4

    The second assertion on that page (CO2 traps heat) is false in any measurable sense, especially in atmospheres. Even the assertion that CO2 is rising since pre-industrial days is faked: http://canadafreepress.com/index.php/article/18343 .
    The scatterplot points for the 19th Century were obtained using EXACTLY the same procedures now used by the best laboratories, minus a few automation tricks.

    Bogus. Every jot and tittle of it.

    #11717

    Transmute wrote: Oil is an excellent fuel if only there was a way that fusion power could make oil

    Yep, which is why oil is so difficult to replace. But it’s also filthy, toxic, and pollutes when burned.

    Fusion = cheap electricity = cheap hydrogen from the electrolysis of water.

    And that hugely reduces the need to use fossil fuels. Cheap hydrogen combined with atmospheric nitrogen can economically make anhydrous ammonia, which is a transportation fuel, as well as a precursor to fertilizer. Google:

    anhydrous ammonia transportation fuel

    and see.

    Before he died in 2010, peak-oil maven (and energy investment banker) Matthew Simmons claimed he had funding for a large windturbine farm to be situated far off the coast of Maine (where the Continential shelf creates the shallow waters that makes a far-offshore wind farm practical). The hope was electricity would be so cheap it would make off-shore production of ammonia possible. For reasons no one seems to know, the plan died with Simmons.

    Ammonia has less energy density than gasoline, but it is far less toxic, and contains no carbon (NH3) — which means it burns without ANY carbon pollution (no CO, no CO2). It is also relatively easy to store (easier than natural gas) and the USA already (in connection with its use as a fertilizer precursor) has a national pipeline and storage system for it. Existing cars can burn ammonia with modest modifications, and there is research into a diesel style ammonia engine (very high compression, no spark plugs or the electronic equivalent).

    If nothing else, for the short term (decades) an ammonia-based transportation system would free up natural gas to be used as an industrial feedstock. Ditto oil. Both are arguably too valuable to burn. One irony of a transition to ammonia is suddenly carbon might become suddenly valuable (for future synthesis of methane from atmospheric hydrogen) — so coal would return + hydrogen for Fischer–Tropsch synthesis.

    The bigger problem may be metalurgy. Statistics on worldwide reserves (for example, of copper) hide a decline that has been consistent since antiquity in the *quality* of ore. The earliest discovered copper was probably pure — pure enough for someone pounding rocks to notice something really special. But by 1850 good copper ore was 6% copper. By 1900 1.5%, and today less than 1%.

    To some extent, cheap energy overcomes that problem (processing is ore is cheaper, digging deeper is cheaper) but the problem may be a fundamental limit on the fantasy of perpetual industrial growth. A lot of what made the USA so rich 100 years ago was plentiful anthracite coal and iron ore of the Messabi range that was 60% pure and ready to dump into blast furnaces. Now most anthracite is gone, and good iron ore is only 35% pure and requires processing before being blasted. Cheap electricity may not solve all problems.

    If focus fusion should succeed in its goals (very cheap electricity, aneutronic, decentralized distribution, low capital costs enabling a rapid transition) the social and political and economic implications are beyond imagining. Possibly one could list the primary initial effects:

    — coal mining ceases (until needed for Fischer–Tropsch methane)

    — fission power ceases (so uranium mining and the danger of weapons proliferation decrease)

    — acid rain and mercury poisoning of the ocean (and thereby the foodchain) ends

    — the global warming debate becomes obsolete

    — economic dominance based on fossil fuel riches ends

    — the USA Navy fufills its dream of going all electric (superconducting ship engines, railguns)

    but each of those initiates a cascade of infinitely more consequences. The end of coal mining means an immediate decline in freight rail traffic. The decline of economic dominance based on fossil fuels means other countries become relatively more powerful.

    I am optimistic the world that will emerge will be a better one, but it may not be a familiar one, and imagining it is a job more for novelists than anyone else.

    – Charles

    ===================
    Q: (NYTimes) With science unfolding at such a heady pace, do you think that maybe… science itself has taken the place of science fiction?

    A: (BY RAY BRADBURY) Not for a minute. We’ve always been ahead of them… We went to Mars long before they headed there.

    #11731
    Avatarvansig
    Member

    Now hang on. Skin exposure to Ammonia causes severe burns. how can you say it is safer than gasoline?

    And, don’t tell me CO2 is the nastier alternative to NO2, in combustion products.

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