<html><head></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><div><div>On Dec 25, 2010, at 10:50 PM, Keith Henson wrote:</div><blockquote type="cite"><div><font class="Apple-style-span" color="#000000"><br></font>The *easy* part is making a clean cheap substitutes for fossil fuels.<br>We know how to suck CO2 out of air at a cost of around 100 kWh/t (360<br>kWh per ton of carbon). </div></blockquote><div><br></div>I'm much more interested (and much more skeptical) in a dollars per ton figure than energy per ton. And I'm not even certain CO2 is at the root of the problem, it certainly isn't the most important greenhouse gas, water vapor is, and water vapor is the very thing that current climate models handel so poorly. I just have a hard time getting all worked up over the rise in CO2, OK it has risen from 280 parts per million to 380 parts per million over the last century, but 80 million years ago it was well over 1000ppm and life got along just fine, plant did rather better that they do now in fact. Plants like CO2, that's why commercial greenhouses deliberately increase it to over 1400ppm. It's also interesting that over the history of the Earth most CO2 increases seem to come after a temperature rise and not before.<br><div><br></div><blockquote type="cite"><div>We know how to make hydrogen either directly from heat (S I process)</div></blockquote><div><br></div>Where does the heat come from?<br><div><br></div><blockquote type="cite"><div>or by electrolysis.</div></blockquote><div><br></div>Even if the electricity came from solar cells that might not be good news for global warming; solar cells are designed to capture sunlight and thus are black, but only about 12% of the light is converted to electricity, so 88% is converted directly into heat. <br><div><br></div><blockquote type="cite"><div><blockquote type="cite">In another design that would probably be even cheaper he just slips a sleeve over the smokestack of any existing small to midsize coal power plant in the higher latitudes and uses the hot exhaust to fill hot air balloons to support the hose.<br></blockquote><br>It's a lot harder than you might think.<br></div></blockquote><div><br></div><div><div><div>Myhrvold is saying that if you want to cure global warming in the northern hemisphere then pick any existing medium sized coal power plant that is not too far from the arctic circle and simply extend the smokestack from 1000 feet its at now to 18 miles. That's it. That sounds a lot easier than a space elevator, or power satellites, or scrubbing the atmosphere clean of CO2; and that last might not even cool the planet, but thanks to Pinatubo we know for sure that sulphur dioxide in the stratosphere will.</div><div><br></div><div> John K Clark</div><div> </div><div><b><br></b></div> </div></div><br><blockquote type="cite"><div><br></div></blockquote></div><br></body></html>