{"id":2281,"date":"2008-02-19T09:53:39","date_gmt":"2008-02-19T09:53:39","guid":{"rendered":"http:\/\/scienceblogs.com\/principles\/2008\/02\/19\/heating-vs-warming\/"},"modified":"2008-02-19T09:53:39","modified_gmt":"2008-02-19T09:53:39","slug":"heating-vs-warming","status":"publish","type":"post","link":"http:\/\/chadorzel.com\/principles\/2008\/02\/19\/heating-vs-warming\/","title":{"rendered":"Heating vs. Warming"},"content":{"rendered":"

Another tidbit from Boskone. At the Sunday afternoon panel on global warming, one of the panelists brought up the fact that the Second Law of Thermodynamics ensures that power generating systems always generate a great deal of waste heat. He wondered about how the waste heat released into the environment compares to the effects of greenhouse warming from CO2<\/sub> emissions. Or, to put it another way, if you could develop some sort of magic carbon sequestration program that would capture every gram of greenhouse gas emitted by a coal-fired power plant, would you still have a problem because of the direct heat produced by burning the coal?<\/p>\n

My immediate reaction would be to say “no,” that is, that the greenhouse gases are a much bigger problem. This is partly because of the localization of the effect– greenhouse gases spread out over the entire atmosphere, and lead to warming everywhere, while a power plant just heats its immediate neighborhood, and that’s more easily contained and mitigated. But it’s mostly because of the scale of the numbers involved.<\/p>\n

<\/p>\n

An electric power plant will have an overall efficiency of something like 30%, meaning that for every megawatt of electricity produced, there will be an additional two megawatts released as waste heat. Total world electricity consumption is something like 16 trillion kilowatt-hours annually, which works out to generating about 1.8 trillion watts on a continuing basis, so let’s call it three trillion watts (3 x 1012<\/sup> W) of heat produced by electrical generation.<\/p>\n

Greenhouse gases, on the other hand, are (loosely speaking) trapping some fraction of the energy dumped onto the Earth by the Sun. That works out to about 1.7 x 1017<\/sup> W on average (according to Wikipedia<\/a>). You don’t need to be trapping a large fraction of that to match the direct heating from burning fossil fuels to generate electricity. And, of course, the greenhouse gases only compound any effects from direct heating, because they help retain all<\/strong> of the heat generated at the surface of the planet, whatever the source.<\/p>\n

It turns out to be maddeningly difficult to get any more quantitative than this, though. I can easily Google up figures like the average production of CO2<\/sub> by various types of power plants (roughly 8,000 tons per year<\/a> for a one-megawatt plant), and find that that’s roughly one one-millionth of the total annual emission of CO2<\/sub><\/a>, which would be around 0.25% of the total mass of CO2<\/sub> in the atmosphere (3 x 1015<\/sup> kg<\/a>). I’m coming up blank on any kind of warming-per-ton figure, though, probably because it’s a fiendishly difficult calculation requiring computer simulations of inflow and outflow and all that fun stuff.<\/p>\n","protected":false},"excerpt":{"rendered":"

Another tidbit from Boskone. At the Sunday afternoon panel on global warming, one of the panelists brought up the fact that the Second Law of Thermodynamics ensures that power generating systems always generate a great deal of waste heat. He wondered about how the waste heat released into the environment compares to the effects of… Continue reading Heating vs. Warming<\/span><\/a><\/p>\n","protected":false},"author":2,"featured_media":0,"comment_status":"open","ping_status":"1","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[48],"tags":[],"class_list":["post-2281","post","type-post","status-publish","format-standard","hentry","category-environment","entry"],"_links":{"self":[{"href":"http:\/\/chadorzel.com\/principles\/wp-json\/wp\/v2\/posts\/2281","targetHints":{"allow":["GET"]}}],"collection":[{"href":"http:\/\/chadorzel.com\/principles\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/chadorzel.com\/principles\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/chadorzel.com\/principles\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"http:\/\/chadorzel.com\/principles\/wp-json\/wp\/v2\/comments?post=2281"}],"version-history":[{"count":0,"href":"http:\/\/chadorzel.com\/principles\/wp-json\/wp\/v2\/posts\/2281\/revisions"}],"wp:attachment":[{"href":"http:\/\/chadorzel.com\/principles\/wp-json\/wp\/v2\/media?parent=2281"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/chadorzel.com\/principles\/wp-json\/wp\/v2\/categories?post=2281"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/chadorzel.com\/principles\/wp-json\/wp\/v2\/tags?post=2281"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}