Robin, Excellent suggestion.
Oz should be a candidate for this kind of improvement as well, since your apparently have lots of coal and little methane. Another more advanced option - assuming that powdered coal still has too much engrained ash to burn as cleanly as we would like -- is a two-step process using a "cyclone" type of preburner (modified for the purpose, of course). The powdered coal would be burned with a little pure oxygen (made at night during off-peak hours) to form hot CO (carbon monoxide) which is then burned with air in the topping turbine. The monoxide gas can be produced almost ash-free this way without expensive pre-processing. The heavier ash, which is not gasified, will be spun out of the cyclone vortex and collected, eliminating the need for the high maintenace "bag house" -- which is the after-the-fact solution that many coal plants have adopted. The cyclone can also be encased in piping to partially raise steam, for even more efficiency. Here is a simple version of what I am talking about http://www.dustcollectorexperts.com/blog/wp-content/uploads/cyclonediag.gif Jones ----- Original Message ---- > From: "mix...@bigpond.com" <mix...@bigpond.com> > This might however offer another interim solution. Gas powered generating > plants > have become important in recent years for two reasons. > > 1) CH4 produces less CO2 / BTU, and > 2) The gas can be burnt in a "topping" turbine, the exhaust heat of which is > used to boil water to produce steam for a conventional steam turbine. > > This combined cycle is frequently around 60-70% efficient, as opposed to a > steam > turbine alone, which is usually no more than about 40% at best. > > Now, if powdered coal were to replace the gas in the gas turbine portion of > the > system, then one would theoretically have a system that could still achieve > 60-70% efficiency, but running purely on coal rather than natural gas. > > IOW the greenhouse gas results would lie somewhere between a gas powered plant > and a normal coal fired plant (and it would increase the profits of the power > companies because they would consume less coal). > > Furthermore, the characteristics of the process that were problematic for > automotive use could easily be dealt with in a stationary application. > > This would also tie in with the Pickens Plan, freeing up natural gas for > automotive use. > > >Eco-nightmare or valid alternative? > > > >http://www.nytimes.com/2009/01/04/automobiles/04COAL.html?pagewanted=1&_r=1 > > > [snip] > Regards, > > Robin van Spaandonk > > http://rvanspaa.freehostia.com/Project.html
