All I don't know where Thomas Koch got the 50%, but 10-20% is much more reasonable based on DRY WOOD as a starting point.
Tom Reed n Thomas B Reed On Jul 17, 2012, at 8:51 PM, Peter & Kerry <[email protected]> wrote: > On 18/07/2012 5:00 AM, [email protected] wrote: >> From: Thomas Koch<[email protected]> >> >> Subject: Re: [Gasification] BIOCOAL - THE WOOD FUEL OF THE FUTURE >> >> But it will cost 50 % of the heating value of the wood > > Thomas, I am unsure where this number comes from could you give more detail? > > In straight energy recovery terms it really depends on a number of factors > including level of torrefaction as determined by temperature and residence > times. We would expect 90% retained energy for the product we are aiming for, > though the overall energy efficiency of the process will be lower as a % of > the original wood delivered to the plant is used to run the process. The > trade off is a "specified" fuel with much higher utility, far better > transport economy (not carting energy robbing water), problem free storage > and handling with existing coal equipment and uniform very low emission > combustion performance vs raw wood fuel. When the first commercial pilot is > complete then we will do a energy balance measurement (to compare with the > theoretical calculation). > > Although in our circumstance this more for academic interest and as a > benchmark to judge future process improvements as in any case the the > argument is somewhat moot, current practice (burning waste in Beehive > burners) recovers 0% of the embodied waste wood energy for a negative cost to > the business. The potential clients they have are not interested in straight > wood chip or sawdust as the low energy density and higher handling > requirements preclude their "raw" use in their existing coal fired boiler > plant at anything like a reasonable co-firing rate (sawdust/chip is usually > limited to <5% of fuel feed). New biomass optimised boilers have been ruled > out because of their very high cost. > > In one case that we have been asked to consider the fuel spec is so tight in > terms of energy density and form that it can only be met by making a blended > torrefied wood/charcoal pellet (one approach to achieve this is tweaking the > operating parameters of the gasifier in favour of more char production and > combining this with the fines from TW retort through a densification plant). > Technically this can be done, making it work economically is the bigger > challenge. > > Leland also makes a interesting point: >> There is a company formed to make torrified wood. I am terrified of the >> prospects as it would be a lot easier to gasify wood at the site of coal use. > We have tried hard over the years arguing the same case. The reality though > is what we call technology inertia, businesses stay with the energy > technology they know (straight combustion of solid fuels in the cases we are > talking about), they will accept an "improved" solid fuel that does not > require much in the way of change to "business as usual" so long as the > decision can be easily reversed if it doesn't work out. Interestingly if they > are already using a gas fuel, such as LPG then they can much more easily be > persuaded to consider an on site gasifier. > > Which raises an interesting future scenario in those countries where large > scale fracking is taking place and "cheap" abundant gas supplies are becoming > available. Changing over from coal to another fossil fuel, in this case Coal > seam or Oil shale gas is a straight forward economic decision by businesses > with boilers, particularly where industry price competition is also driving > the change. Once this occurs then "step change" to on site gasifiers will > become easier in the future a the vastly expanded gas industry gets past its > first flush, new energy players fail & or merge to form more monopolistic > entities and the gas prices inevitably rise. > > Cheers, > > Peter > > > > > > _______________________________________________ > Gasification mailing list > > to Send a Message to the list, use the email address > [email protected] > > to UNSUBSCRIBE or Change your List Settings use the web page > http://lists.bioenergylists.org/mailman/listinfo/gasification_lists.bioenergylists.org > > for more Gasifiers, News and Information see our web site: > http://gasifiers.bioenergylists.org/ _______________________________________________ Gasification mailing list to Send a Message to the list, use the email address [email protected] to UNSUBSCRIBE or Change your List Settings use the web page http://lists.bioenergylists.org/mailman/listinfo/gasification_lists.bioenergylists.org for more Gasifiers, News and Information see our web site: http://gasifiers.bioenergylists.org/
