The state\u2019s fourth carbon cap-and-trade auction on Aug. 16 received $275.5 million from the sale of 24.4 million greenhouse gas emission allowances. One allowance equals a metric ton of carbon dioxide or equivalent greenhouse gas emissions. The California Air Resources auction included the sale of 13.8 million of 2013 allowances at $12.22\/allowance. The total sale for this year\u2019s vintage allowances was $169.4 million, the agency reported Aug. 21. Bidders included oil companies, private and public utilities, independent generators, and traders, including JP Morgan. At the end of last week, the price exceeded the bid floor of $10.71\/allowance, but was lower than previous quarterly auction prices. During its Feb. 19 emissions auction, the clearing price for 2013 vintage allowances approached $14\/ton, up from little more than $10\/ton in the first auction held in November 2012. The market at that time was said to be \u201cmaturing,\u201d according to analysts. For the first time last week, the Air Board also sold 2016 vintage allowances\u20149.5 million of them for a total $106 million. The price per allowance was $11.10. Last March, the Air Board canceled its scheduled March 8 reserve carbon credit sale due to lack of interest because of the low price of credits. In the reserve sales, the Air Board is to offer credits it holds in an effort to moderate the price of carbon.