Reply To: Fusion Oil

[JimmyT]

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?