Hi Keith (& all), Good "tutorial" on hydrogen. After reading it I wondered whether Amory Lovins and/or the folks at Rocky Mountain Institute <http://www.rmi.org> had anything to say about hydrogen as fuel, about generating hydrogen, or about bacterial generation of hydrogen in particular?
The answers are yes, yes, no. I was surprised by the "no". BUT, Lovins has some material hot-off-the-press (2 September) about hydrogen fuel and hydrogen fuel-cell energy production. I will pass on the references and a snippet to give the flavour of a Lovins tutorial (which is almost as good as a Hudson tutorial!). You can just go to the home page of Rocky Mountain Institute <http://www.rmi.org> and poke around. There are various links to different topics and a "keyword" Search option. Prominently displayed you will find a link to: "Twenty Hydrogen Myths: This paper demystifies H2 energy, debunks popular misconceptions, and proposes a profitable path to the H2 economy..." which will connect you with: http://www.rmi.org/sitepages/pid171.php#20H2Myths a modest & copyable PDF file (~180kB) offering a very thorough and well-documented treatment. Here is an excerpt that fills in some details of issues to which Keith refers: ++++++++++++++++++++++++++++++++++++ **(Myth #3. Making hydrogen uses more energy than it yields, so it's prohibitively inefficient.** Any conversion from one form of energy to another consumes more useful energy than it yields. If it could do the opposite, creating energy out of nothing, you could create a perpetual-motion machine violating the laws of physics. Conversion losses are unavoidable; the issue is whether they're worth incurring. If they were intolerable as a matter of principle, as Myth #3 implies, then we'd have to stop making gasoline from crude oil (~73-91% efficient from wellhead to retail pump) and electricity from fossil fuel (~29-35% efficient from coal at the power plant to retail meter). Such conversion losses are thus not specific to producing hydrogen. Hydrogen production is typically ~72-85% efficient in natural-gas reformers or ~70-75% efficient in electrolyzers; the rest is heat that may also be reusable. (These efficiency figures are all reduced by 15% because of the way hydrogen's energy content is normally measured.) So why incur these losses to make hydrogen? Because hydrogen's greater end-use efficiency can more than offset the conversion losses, much as an electric heat pump or air conditioner can offset fuel-to-electricity conversion losses by using one unit of electricity to concentrate and deliver several units of heat. That is, conversion losses and costs are tolerable if the resulting form of energy is more efficiently or conveniently usable than the original form, hence justified by its greater economic value. Making hydrogen can readily achieve this goal. Crude oil can be more efficiently converted into delivered gasoline than can natural gas into delivered hydrogen. But that's a red herring: the difference is far more than offset by the hydrogen's 2-3-fold higher efficiency in running a fuel-cell car than gasoline's in running an engine-driven car. Using Japanese round numbers from Toyota, 88% of oil at the wellhead ends up as gasoline in your tank, and then 16% of that gasoline energy reaches the wheels of your typical modern car, so the well-to-wheels efficiency is 14%. A gasoline-fueled hybrid-electric car like the 2002 Toyota Prius nearly doubles the gasoline-to-wheels efficiency from 16% to 30% and the overall well-to-wheels efficiency from 14% to 26%. But locally reforming natural gas can deliver 70% of the gas's wellhead energy into the car's compressed-hydrogen tank. That "meager" conversion efficiency is then more than offset by an advanced fuel-cell drive system's superior 60% efficiency in converting that hydrogen energy into traction, for an overall well-to-wheels efficiency of 42%. That's three times higher than the normal gasoline-engine car's, or 1.5 times higher than the gasoline-hybrid-electric car's. This helps explain why most automakers see today's gasoline-hybrid cars as a stepping-stone to their ultimate goal - direct-hydrogen fuel-cell cars. [all notes deleted - SS] [Copyright © 2003 Rocky Mountain Institute. All rights reserved. www.rmi.org] from: "Twenty Hydrogen Myths" (#E03-05) by Amory B. Lovins, CEO, Rocky Mountain Institute (20 June 2003, corrected and updated 02 September 2003), pp. 10-11 http://www.rmi.org/sitepages/pid171.php#20H2Myths [PDF doc] ++++++++++++++++++++++++++++ A digest version of "Twenty Hydrogen Myths" is available as an HTML file: "Amory B. Lovins's Hydrogen Primer: A Few Basics About Hydrogen" http://www.rmi.org/sitepages/art7516.php KEITH - You're a certified chemical engineer [:)]. I think it would be interesting to send your tutorial on the bacterial generation of hydrogen off to Lovins and see what he and the folks at RMI have to say. You might get invited out to Snowmass, CO for a briefing/debriefing! best wishes, Stephen Straker <[EMAIL PROTECTED]> Vancouver, B.C. [Outgoing mail scanned by Norton AntiVirus] _______________________________________________ Futurework mailing list [EMAIL PROTECTED] http://scribe.uwaterloo.ca/mailman/listinfo/futurework
