Independent refiner Tesoro Corporation TSO reported first-quarter 2016 adjusted earnings from continuing operations of $1.19 per share, which surpassed the Zacks Consensus Estimate of $1.04. The bottom line also came higher than the year-ago quarter figure of 98 cents. Significant contribution from the marketing segment following considerable consumer demand supported the results. This was negated partially by the plunge in refining margin. Tesoro Corporation (TSO) Street EPS & Surprise Percent - Last 5 Quarters | FindTheCompanyTesoro Corporation reported quarterly revenues of $5,101 million, which decreased from $6,463 million in the comparable quarter last year. However, it beat the Zacks Consensus Estimate of $3,590 million. Segmental AnalysisRefining: The segment posted an operating income of $196 million, considerably lower than $256 million earned in the year-earlier quarter. Decrease in refining margins hurt the results. TLLP: During first-quarter 2016, TLLP contributed $174 million to operating profit, up from $168 million in the year-ago quarter. The improvement can be attributed to higher revenues from terminalling and transportation operations.Marketing: The segment earned $239 million, reflecting a significant increase from $145 million in the first quarter of 2015. Strong consumer demand primarily led to the improvement. ThroughputTotal refining throughput averaged 782 thousand barrels per day (MBbl/d), higher than 696 MBbl/d in the prior-year quarter.Overall throughput volumes in California (consisting of Martinez and Los Angeles refineries) increased 9.2% year over year to 461 MBbl/d. Throughput in Tesoro Corporation's Pacific Northwest (Alaska and Washington) operations increased to 186 MBbl/d from 158 MBbl/d in the year-ago comparable quarter. Moreover, throughput volumes in Mid-Continent (North Dakota and Utah) grew 16.4% year over year to 135 MBbl/d.Refining MarginsGross refining margin slipped 17% year over year to $9.66 per barrel. Region-wise, refining margin recorded an increase of almost 9% to $11.64 per barrel in California, a decline of 50.2% to $7.88 per barrel in Mid-Continent and a fall of over 45.4% to $5.98 per barrel in Pacific Northwest, all on a year-over-year basis. Realized Costs & PricesManufacturing costs before depreciation and amortization decreased 12.3% from the year-earlier level to $5.55 per barrel.Total refined product sales averaged 952 Mbbl/d, higher than 899 Mbbl/d in the first quarter of 2015.Average price realized on product sales fell 26% year over year to $54.79 per barrel and average cost per barrel was down 25% to $48.93 per barrel.Operating CostTesoro Corporation's operating costs in the reported quarter came in at $616 million, marking an increase of 7% from the year-ago quarter.Capital Expenditure & Balance SheetTesoro Corporation's total capital spending in the reported quarter (including TLLP) totaled $188 million (63.3% directed toward refining segment).As of Mar 31, 2016, the company had $439 million of cash on hand and long-term debt of $4,046 million, representing a debt-to-capitalization ratio of 34.6%. GuidanceTesoro Corporation expects throughput margin for the second quarter between 795 MBbl/d and 840 MBbl/d.Zacks RankTesoro Corporation currently carries a Zacks Rank #3 (Hold).Some better-ranked players in the energy sector include PetroChina Co. Ltd. PTR, Seadrill Partners LLC SDLP and Braskem S.A. BAK. Each of these stocks sports a Zacks Rank #1 (Strong Buy).Want the latest recommendations from Zacks Investment Research? Today, you can download 7 Best Stocks for the Next 30 Days. Click to get this free report >>Want the latest recommendations from Zacks Investment Research? Today, you can download 7 Best Stocks for the Next 30 Days. Click to get this free report TESORO CORP (TSO): Free Stock Analysis Report PETROCHINA ADR (PTR): Free Stock Analysis Report BRASKEM SA (BAK): Free Stock Analysis Report SEADRILL PTNRS (SDLP): Free Stock Analysis Report To read this article on Zacks.com click here.