{"id":782,"date":"2010-06-09T20:51:24","date_gmt":"2010-06-10T03:51:24","guid":{"rendered":"https:\/\/c21-wp.phas.ubc.ca\/index.php\/clean-coal"},"modified":"2023-03-31T14:14:58","modified_gmt":"2023-03-31T21:14:58","slug":"old-clean-coal","status":"publish","type":"article","link":"https:\/\/c21.phas.ubc.ca\/article\/old-clean-coal\/","title":{"rendered":"OLD Clean Coal"},"content":{"rendered":"

Reasonable quality coal of the type used in power stations has an energy content (higher heating value<\/em>, or HHV) of around 30 MJ\/kg. This number varies considerably depending on the source of coal. The chemical formula for coal is roughly (CH)n<\/sub>. Let’s calculate how much coal we have to burn in a typical large power station to produce 1 GWe<\/sub> for a year. For this we have to assume a conversion efficiency \u03b7<\/em> for thermal to electrical energy. Really good modern steam generators have\u00a0\u03b7\u00a0\u2248 <\/em>0.4, so to generate 1 GWe<\/sub> we’ll need a a thermal power of 1\/0.4 = 2.5 GWth<\/sub>.<\/p>\n

The total amount of thermal energy required to generate 2.5 GWth<\/sub> for one year is<\/p>\n

(2.5)(3600 s\/h)(24 h\/d)(365 d\/y)(109<\/sup> W) = 7.9 x 1016<\/sup> J.<\/p>\n

The mass of coal that needs to be burnt to produce this energy is<\/p>\n

(7.9 x 1016<\/sup>\u00a0J)\/(30 x 106<\/sup> J\/kg) = 2.6 x 109<\/sup> kg = 2.6 Mtonnes.<\/p>\n

To convert this mass of coal to the mass of CO2<\/sub> produced on burning, consider the chemical reaction:<\/p>\n

4CH + 5O2<\/sub> \u2192 4CO2<\/sub> +\u00a02H2<\/sub>O<\/p>\n

As, always when burning fossil fuels, every carbon atom in the fuel ends up in a CO2<\/sub> molecule. The molecular mass of CH is 13; that of CO2<\/sub> is 44. Thus 13 tonnes of coal produce 44 tonnes of CO2<\/sub>.<\/p>\n

In other words, the\u00a02.6 Mtonnes of coal burnt each year in a 1 GWe<\/sub> power station produces (2.6)(44\/14) = 8.9 Mtonnes of CO2<\/sub>.<\/p>\n

As we are using some rough numbers here and also ignoring CO2<\/sub> emissions caused by mining and transportation of coal, let’s call our result 10 Mtonnes of CO2<\/sub> per GWe<\/sub> per year. Its hard to know what to do with 10 million tonnes of anything, let alone a gas (which at STP[note]Hyper Physics.\u00a0 Ideal Gas Law<\/em> (online). \u00a0http:\/\/hyperphysics.phy-astr.gsu.edu\/hbase\/kinetic\/idegas.html<\/a>\u00a0 [9 June 2010].[\/note] would fill 5 cubic km). However, this is the CO2<\/sub> production from only one large coal-fired plant in one year. Two such plants are being opened in China every week<\/em>[note]BBC News.\u00a0 China Building More Power Plants <\/em>(online).\u00a0 http:\/\/news.bbc.co.uk\/2\/hi\/asia-pacific\/6769743.stm<\/a>\u00a0 [9 June 2010].[\/note]. Although ideas and plans abound[note]Wikipedia.\u00a0 Carbon Capture and Storage<\/em>\u00a0(online). \u00a0http:\/\/en.wikipedia.org\/wiki\/Carbon_capture_and_storage<\/a>\u00a0 [9 June 2010].[\/note], no plant yet disposes of any significant quantity of CO2<\/sub> anywhere other than in the atmosphere.<\/p>\n","protected":false},"author":6,"featured_media":2133,"template":"","tags":[83,123,114,96],"date_post_made_public":"0000-00-00","post_authored_by":"","hook":"

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\r\n\r\nAn oxymoron?\r\n\r\n<\/div>\r\n<\/div>\r\n<\/div>","big_ideas":"
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  • For calculating the greenhouse gas production due to burning any fossil fuel, all you need is the energy content and a rough chemical formula.<\/li>\r\n<\/ul>","thumbnail_for_post":"\"\"","series":false,"number_in_series":"0","supporting_classroom_materials":false,"supporting_experiment":false,"related_articles":false,"related_experiments":false,"related_classroom_materials":false,"_links":{"self":[{"href":"https:\/\/c21.phas.ubc.ca\/wp-json\/wp\/v2\/article\/782"}],"collection":[{"href":"https:\/\/c21.phas.ubc.ca\/wp-json\/wp\/v2\/article"}],"about":[{"href":"https:\/\/c21.phas.ubc.ca\/wp-json\/wp\/v2\/types\/article"}],"author":[{"embeddable":true,"href":"https:\/\/c21.phas.ubc.ca\/wp-json\/wp\/v2\/users\/6"}],"version-history":[{"count":6,"href":"https:\/\/c21.phas.ubc.ca\/wp-json\/wp\/v2\/article\/782\/revisions"}],"predecessor-version":[{"id":2500,"href":"https:\/\/c21.phas.ubc.ca\/wp-json\/wp\/v2\/article\/782\/revisions\/2500"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/c21.phas.ubc.ca\/wp-json\/wp\/v2\/media\/2133"}],"wp:attachment":[{"href":"https:\/\/c21.phas.ubc.ca\/wp-json\/wp\/v2\/media?parent=782"}],"wp:term":[{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/c21.phas.ubc.ca\/wp-json\/wp\/v2\/tags?post=782"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}