On Sat, 29 Oct 2011 05:46:43 -0700 (PDT) Curt Raymond <curtlud...@yahoo.com> wrote:
> Definitely something on my mind. > http://www.otherpower.com/steamengine.shtml > We've got mostly poplar (quaking aspen really) and spruce but a steam > generator wouldn't mind what fuel it was burning only that there was > plenty of supply. I suspect I could make 2kw for most of a year just on > deadwood right now... With the following assumptions: - quaking aspen having about 15 million BTU per cord - system efficiency 10% from fuel to electricity 1.5e7 BTU 1055 J 1 W-s 1 kWh --------- x 0.1 x ------ x ----- x --------- = 439.6 kWhe cord BTU J 3.6e6 W-s Note that the system efficiency (an indication of the heat losses) here is the determining factor. If you were burning the wood for heating you would utilize more of the energy available. Now if you had the entire steam-powered generator within a living space, you could heat and generate electricity at the same time, though that would not be so good during the summer. Note also that the energy content is the "high heat value", that of oven-dry wood. You will lose 5 - 10% for the moisture in air dry wood. The fellow at the link says he gets 1 kWh from 60 pounds of lodgepole pine. Lodgepole pine has a high heat value about 17.2 million BTU per cord and has a specific gravity of 0.41. Assuming 80 ft^3 of actual wood per cord, ft^3 1 cord 60 lb x -------------- x ------- = 0.0294 cord 0.41 x 62.3 lb 80 ft^3 1.72e7 BTU 0.0294 cord x ---------- = 505030 BTU cord Since 1 kWh is 3412 BTU, we have an input of 505030 BTU and an output of 3412 BTU, for a system efficiency of 0.68%, somewhat lower than the 10% I guessed above. Going from just the fellow at the link's number (1 kWh / 60 lb), you would have, 1 kWh 34.01 kWh ----------- = ----------- 0.0294 cord cord To put things to scale, 1 kWh is 2.66 million foot-pounds. At least I think all of this is correct. Maybe someone can point out my errors (in arithmetic, if nothing else). Craig _______________________________________ http://www.okiebenz.com For new and used parts go to www.okiebenz.com To search list archives http://www.okiebenz.com/archive/ To Unsubscribe or change delivery options go to: http://mail.okiebenz.com/mailman/listinfo/mercedes_okiebenz.com
