Forward from the stoves list at Crest. >Delivered-To: mailing list [EMAIL PROTECTED] >From: "Tom Reed" <[EMAIL PROTECTED]> >Subject: Hydrogen Economy greatly overrated, biomass underrated... >Date: Sat, 21 Sep 2002 14:18:03 -0600 >Organization: BEF > >Dear All Biomassers: > >The message below from my good friend Tom Milne, Bob Evans and all >anouncing a new report on hydrogen needs to be put in context. >Speaking as a fuel scientist, I hope I may be permitted a personal >diatribe in this forum. If you are emotionally convinced that >hydrogen is the world's best fuel, and wish to stay convinced, >delete this message. . > ~~~~~~~~~ >HYDROGEN has been known and used since the early part of the 19th >century. It is easy to make in the laboratory from iron and HCL or >by electrolysis. > >Hydrogen is unique amongst the elements with outstandingly good and >bad properties. > >As a fuel it has the highest Mass Energy Density of any fuel by a >large margin, so liquid hydrogen isn't too bad a fuel if you can >afford the cost and keep it well insulated. As a gas it also has a >very low Volume energy density (same as CO, 1/3 that of methane). >It is an important component of synthesis gas (CO + H2) and producer >gas (CO + H2 + N2). > >Hydrogen also has a flame velocity (2.83 m/s in air compared to .5 >m/s for methane, propane etc.). For this reason it is a difficult >automotive fuel, since stoichiometric combustion produces "hydrogen >knock". However, it has the widest flamability limits so can be >burned very lean for better efficiency. > >Another hydrogen problem I haven't heard discussed is that it >contracts chemically 1/3 on burning according to > >H2 + 1/2 O2 [1.5 moles or voumes] ===> H2O [1 mole] > >by contrast, methane gets full value, since CH4 + 2 O2 [3 moles] >===> CO2 + 2 H2O [3moles] > >~~~~~~~ >Hydrogen is an important chemical for converting vegetable oils to >margarine etc. and is widely used in large chemical plants. >Electrolysis of water to make hydrogen is only 72% efficient (due to >high overvoltage), and conversion of heat to electricity is >typically 30% efficient, so electrolysis is 18% base efficiency. >Hydrogen can be made from methane and hydrocarbons using steam >reforming and the water gas shift reaction - probably 80% efficient. > >So for 150 years pure hydrogen was only used by quartz workers. >However, many gases, including our producer gas, can contain large >fractions of hydrogen - 18% in our current producer gas at CPC. > >~~~~~~~~ >So how has hydrogen risen so high in research circles as a target fuel? > >It all started with "The Hydrogen Economy" about 1970. At that time >we were naively told that nuclear electric power would be too cheap >to meter in a short time (Ha!). But you can't run a car on >electricity so we would still need a "fuel tank". Since power had >no cost, hydrogen from water would have no cost! Voila. I remember >hearing these arguments at the first "Hydrogen Economy" conference >held appropriately at the Playboy Club in Miami about 1974. > >We have since become disenchanted with the nuclear energy side of >this argument, but dreamers still talk of hydrogen combustion being >"non polluting" and therefore the ultimate fuel. > >Today's cars are amazingly clean compared to those of the smoggy >''70s, so they are relatively "non polluting" in the atmospheric >sense. However our current fossil fuels do increase atmospheric CO2 >levels so can be considered "polluting" from a global warming >perspective. Don't worry, the oil will be gone soon at the present >rate of usage/wastage. > >For a REALISTIC view on hydrogen, check out.. >http://www.nrel.gov/ncpv/hotline/pdf/hydrogen_economy.pdf > >Your Skeptical Fuel Scientist, TOM REED >BEF GASWORKS > >----- Original Message ----- >From: "Milne, Thomas" [EMAIL PROTECTED]> >To: "Milne, Thomas" [EMAIL PROTECTED]>; [EMAIL PROTECTED]>; >[EMAIL PROTECTED]>; [EMAIL PROTECTED]> >Sent: Friday, May 24, 2002 12:36 PM >Subject: GAS-L: RE: Biomass to Hydrogen Report Web Address > > > > > > > > -----Original Message----- > > > From: Milne, Thomas > > > Sent: Friday, May 24, 2002 11:27 AM > > > To: <mailto:'[EMAIL PROTECTED]'>'[EMAIL PROTECTED]'; ><mailto:'[EMAIL PROTECTED]'>'[EMAIL PROTECTED]'; ><mailto:'[EMAIL PROTECTED]'>'[EMAIL PROTECTED]'; > > > <mailto:'[EMAIL PROTECTED]'>'[EMAIL PROTECTED]' > > > Subject: FW: Biomass to Hydrogen Report Web Address > > > > > > Interested parties may access our recent IEA report, "Hydrogen from > > > Biomass--State of the Art and Research Challenges", at the WEB address > > > listed below. The authors would welcome corrections or additions to > > > references, as a supplement for Year 2002 is planned. > > > > > > Tom Milne, Carolyn Elam and > > > Robert Evans. > > > > > > > > > -----Original Message----- > > > From: Elam, Carolyn > > > Sent: Thursday, February 28, 2002 11:10 AM > > > To: Milne, Thomas > > > Subject: Biomass to Hydrogen Report Web Address > > > > > > http://www.eren.doe.gov/hydrogen/iea/pdfs/hydrogen_biomass.pdf
------------------------ Yahoo! Groups Sponsor ---------------------~--> Sell a Home for Top $ http://us.click.yahoo.com/RrPZMC/jTmEAA/ySSFAA/9bTolB/TM ---------------------------------------------------------------------~-> Biofuels at Journey to Forever http://journeytoforever.org/biofuel.html Biofuel at WebConX http://www.webconx.dns2go.com/2000/biofuel/biofuel.htm List messages are archived at the Info-Archive at NNYTech: http://archive.nnytech.net/ To unsubscribe from this group, send an email to: [EMAIL PROTECTED] Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
