[Gasification] CONSERVATION OF ENERGY

[Kevin]

Dear Tom

Thanks very much for the specific real numbers for the energy available from a pound of Aluminum.

Assuming that scrap Aluminum sells for $1 per pound, then the cost of the energy in the Hydrogen produced is thus $1/3.3 = $.30 per kw-hr, assuming 100% conversion to Hydrogen. 

In comparison, purchased wood pellets cost about $5 per 40 pound bag, or $.125 per pound, and each pound of pellets contains about 8,500 BTU, or about 2.5 kw-hr per pound.  In this case, the cost of contained energy is about $.125/2.5 = $.05 per kw-hr, ie, about 1/6 as much.

As I understand it, the best practical efficiency of a Fuel Cell running on Hydrogen is about 60%; this would cost of energy for electricity of about $.30/.6 = $.50 per kw-hr.

A biomass gasifier has a typical efficiency of about 70%, giving a cost of the gas energy of about $.05/.7 = $.071 per kw-hr. If this gas is sent to an internal combustion engine with an efficiency of 25%, shaft power thus costs about $.284 per kw-hr; if the shaft was connected to a generator with 80% efficiency, then the energy cost of power from high cost wood pellets would be about $.284/.8 = $.357 per kw-hr.

There was a discussion about an "Earth Battery" using Aluminum as the energy source. Would you have any idea of the conversion efficiency of Aluminum to Electricity in such an "Earth Cell?" More particularly, would the efficiency of such an "Earth Cell" be lower than, approximately equal to, or higher than, a Fuel cell?

Thanks, and Best wishes,

Kevin
  ----- Original Message ----- 
  From: Thomas Reed 
  To: Discussion of biomass pyrolysis and gasification ; Art Krenzel 
  Cc: Gasification at bioenergylists.org 
  Sent: Tuesday, July 12, 2011 9:52 PM
  Subject: Re: [Gasification] CONSERVATION OF ENERGY


  PS. 


  According to my book, THE FREE ENERGY OF BINARY COMPOUNDS (available at Woodgas.com)


  The Enthalpy of combustion of Al 


  Al + 3/2 O2 ==> 1/2 Al2O3.   Delta H (C) = 178 kcal/mole = 745 kJ/mole.  The MW of Al is 27, so this is 27.6 kJ/g or 12,527 kJ/ lb.  1 kW hr is 3.8 MJ, so this is 3.3 kW hr/lb. 


  Well worth capturing.


  Tom Reed

  Dr Thomas B Reed
  President, The Biomass Energy Foundation
  www.Woodgas.com

  On Jul 12, 2011, at 7:51 PM, GF <gfwhell at aol.com> wrote:




        
    The other day I posted an article on this site concerning:
     Cornish Hydrogen Generator. Keelynet,  which describes a method of converting
    Aluminum into its oxide and in the process cracks water, freeing up hydrogen for use as fuel for a light car.
    By all accounts, using this gas in the place of any other fuel.
    Distances and the amount of metal used in this attainment were mentioned.
    I was hoping for a reaction from one of the many “Energy Economists”
    Who lurk on this site, to respond with negative information regarding the impracticality and waste fullness of such a process?
    I believe there is a large following on this site who are interested in obtaining electrical power using renewable energy, derived from carbon neutral sources.
    They might question the economics and ethics of using a refined ore as fuel.
    Instead of chopping down oxygen producing vegetation.  
    In this respect I am a nonconformist. I believe most Aluminum is produced by Hydro electric power and, so the CO2 is not in the equation.
    My second comment is harnessing a “free” supply of high temperature heat which is emitted from most Ice’s in the form of “Hot Exhaust”.
    This is the place to install a reactor capable of converting beer cans into hydrogen as not too much energy would be needed to complete the reaction. Bubbling super heated steam through a molten bath of AL would give pure hydrogen.
    No tar, and the ash is a hot commodity

    The real question is: how much energy is locked up in a pound of AL

    gfwhell


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