Ken,
I have some minor problems to consolidate the efficiency assumptions. My information is that power stations have 30 to 50 and slightly above and from small to large. I also understand that this is the same as for fuel cells 30 to 50 and from small to large. Chargeable batteries have an efficiency in the range of 80%, according to my understanding. On heat engines we have the same understanding. I also understand that Hydrogen molecules are so small that it is much larger containment problems than Natural Gas. It is no compatibility between equipment for Natural gas and Hydrogen. I saw that the fuel tank for one of the hydrogen car prototypes had a cost of $20,000. R/P value for US Natural gas is around 7 years and for the world 60 years. To use NG is even a less sustainable situation than oil. Producer gas from coal would probably be an alternative, but it is very dirty and it is therefore the politicians do not want to talk about it. It is however the realistic and logic outcome of the Bush hydrogen alternative. It could extend the use current energy consumption at low cost with 50 to 100 years. It would also make US less dependent on oil imports. My suspicion is that the much advertised US hydrogen economy will turn out to be a Producer gas (Gengas) economy, based on the larges domestic coal reserves in the world. US will never join the Kyoto agreement. The technical discussions that we now have are more than half a century old or 70 years. Hakan At 11:47 AM 9/22/2003, you wrote: >Hi All > >I agree about H2 fuel cell efficiency, but extra >electric power generation will be needed just the >same. Using a 20-horesepower average figure means hp >delivered by the engine and this is usually advertised >as ~25%. Better to convert back to Watts (1 hp = 746 >Watts ~ 750 W). 20-hp (15kW) delivered means the >engine is using 60kW of fuel (60kJoules per sec). > >All heat engines are limited by the Carnot cycle >efficiency =1 ŠLowT/HighT where T is given in Kelvin = >Celsius + 273. If you do the math for letās say a >steam turbine with a LowT = 100C = 373K and a HighT of >800C = 1073K the maximum possible efficiency is 65%. >Thereās no way around this with a heat engine! Using >higher T differences and cogeneration, I read >somewhere that modern power plants can get up to 70% >efficiency? > >Batteries and fuel cells are NOT heat engines and >efficiencies can get up to 100% in a perfect world. >The worldās not perfect and I guess maybe 90% >efficiency for a H2 charge/discharge. A round trip is >90% x 90% ~80%. Assuming 70% efficiency for a modern >power plant, this means an overall efficiency of >80%x70% = 56%. This is more than twice as good as a >fuel car engine, so yes itās a better way to go. Itās >the extra infrastructure that will cost a lot of money >and is there the political will to spend a whole lot >of money on this? California would not be a good >place to depend on a H2 fuel cell car! > >Itās true that most homes in the US have natural gas >and could be exploited for H2. Iām not sure how you >turn CH4 into 2H2 + C. A natural gas heat engine >generator will work to electrolyze water, but it seems >like youāre going around in circles this way. Why not >just convert your gasoline car to natural gas and >avoid all the hassle? Pump the home natural gas into >the carās ćgasä tank. > >I advocate an aluminum economy. Aluminum tends to be >electrolyzed from ore using hydroelectric power in >places like Canada. > >BTW I have a ~12kW very low cost solar concentrator >design if anyone is interested. It can power external >heat engines like turbines, Stirling, Thermoacoustic >Stirling, steam and you get hot water in the first >world and/or sterilized water in the third world, like >Indonesia. > >Ken ------------------------ Yahoo! Groups Sponsor ---------------------~--> ReplayTV: Control live television Special Sale: 50% off ReplayTV CNet Ranked #1 over Tivo! http://us.click.yahoo.com/aUMW7B/A6qGAA/ySSFAA/FGYolB/TM ---------------------------------------------------------------------~-> Biofuel at Journey to Forever: http://journeytoforever.org/biofuel.html Biofuels list archives: http://archive.nnytech.net/ Please do NOT send Unsubscribe messages to the list address. To unsubscribe, send an email to: [EMAIL PROTECTED] Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
