Extract CO2 from the atmosphere!
> On Oct 3, 2013, at 1:20 PM, Crispin Pemberton-Pigott > <[email protected]> wrote: > > Dear Jock > >> How would we measure the efficiency of such a system, an iCan TLUD, that > provides useful heat for about 70 minutes from about 3 pounds of wood > pellets and also harvests almost 20% of the weight of the feed stock as > charcoal? > > The system efficiency (which is the work energy divided by the available > fuel energy) is well known for good reasons. It predicts fuel consumption in > future for a similar task, and is a way to rate different technologies with > access to the same amount of the same fuel. > > The rating of the energy performance has to consider whether or not the fuel > left over is useable tomorrow. A good example is an open fire burning > sticks. Each morning the fire is lighted using the wood left over from > yesterday. Maybe the charcoal is left to burn out each night. That has to be > considered as well - if it is burned it is not available tomorrow so it is > consumed even if it did no work. Local behaviour matters when considering > what stove to promote. > > The actual heat available (the effective heating value) is the potential a > stove could get from a given mass of wood with a given moisture content and > elemental analysis. > > The stove may not yield that heat for a variety of reasons which I should > not need to enumerate. If it does not, it is not rewarded with a 'better' > number. If the work done, say, boiling water, remains the same, then it is > not reasonable to reduce the amount of heat available and then say the stove > did a better job because the ratio of the work done to heat yielded is > better. Doing a lousier job of burning the fuel, or making use tomorrow of > what remains today, cannot give a stove a 'better' rating. > > For all these reasons, the fact that there is char remaining at the end of a > cooking cycle is not a bonus for the thermal performance of a cooking > system. > > When using a fuel that is a non-woody biomass, there are good arguments for, > not special consideration, but for a reduction in the requirement for > efficiency. This is reasonable if there is a surplus of an unused resource > and a scarcity of a used one. So the argument that there should be a > 'special' way to calculate the efficiency will not fly. But there is a > chance that pleading a special case based on fuel availability could in > principle succeed. > > In the negotiations on this matter, it is not possible to sell the idea that > a stove that uses more wood than the baseline should be promoted, > particularly on a subsidised basis. It is a much easier sell to show that > there is an unused resource that can 'inefficiently' be used but that will > provide some additional benefits (real, not potential). > > As for emissions into the home the usual standard would apply of course. It > has to be clean burning. > > Regards > Crispin > > > > _______________________________________________ > Stoves 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/stoves_lists.bioenergylists.org > > for more Biomass Cooking Stoves, News and Information see our web site: > http://stoves.bioenergylists.org/ > _______________________________________________ Stoves 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/stoves_lists.bioenergylists.org for more Biomass Cooking Stoves, News and Information see our web site: http://stoves.bioenergylists.org/
