Homer Bhullar
Vice President, Investor Relations & Finance at Valero Energy
Thanks, Joe. Before I provide our second quarter financial results summary, I'm pleased to inform you that we recently published an updated stewardship and responsibility report which now includes our sustainability accounting standards or SASB disclosures. In addition to being on track to achieve our previously announced target to reduce and offset 63% of our global refining greenhouse gas emissions by 2025 through investments in Board-approved projects, the report includes a new target to reduce and offset 100% of our global refining greenhouse gas emissions by 2035.
These targets are consistent with our strategy as we continue to innovate and leverage our global liquid fuels platform to expand our long-term competitive advantage with investments in economic low-carbon projects. And now turning to our quarterly summary. Net income attributable to Valero stockholders was $162 million or $0.39 per share for the second quarter of 2021 compared to $1.3 billion or $3.07 per share for the second quarter of 2020. Second quarter 2021 adjusted net income attributable to Valero stockholders was $197 million or $0.48 per share compared to an adjusted net loss of $504 million or $1.25 per share for the second quarter of 2020. For reconciliations to adjusted amounts, please refer to the financial tables that accompany the earnings release.
The Refining segment reported $349 million of operating income for the second quarter of 2021 compared to $1.8 billion for the second quarter of 2020. Second quarter 2021 adjusted operating income for the Refining segment was $361 million compared to an adjusted operating loss of $383 million for the second quarter of 2020. Refining throughput volumes in the second quarter of 2021 averaged 2.8 million barrels per day, which was 514,000 barrels per day higher than the second quarter of 2020. Throughput capacity utilization was 90% in the second quarter of 2021. Refining cash operating expenses of $4.13 per barrel were $0.26 per barrel lower than the second quarter of 2020, primarily due to higher throughput in the second quarter of 2021.
The renewable diesel segment operating income was $248 million for the second quarter of 2021 compared to $129 million for the second quarter of 2020. Renewable diesel sales volumes averaged 923,000 gallons per day in the second quarter of 2021, which was 128,000 gallons per day higher than the second quarter of 2020. The segment set another record for operating income and sales volumes. The ethanol segment reported operating income of $99 million for the second quarter of 2021 compared to $91 million for the second quarter of 2020. The second quarter 2020 adjusted operating loss was $20 million. Ethanol production volumes averaged 4.2 million gallons per day in the second quarter of 2021, which was 1.9 million gallons per day higher than the second quarter of 2020.
For the second quarter of 2021, G&A expenses were $176 million and net interest expense was $150 million. Depreciation and amortization expense was $588 million, and income tax expense was $169 million for the second quarter of 2021. The effective tax rate was 37%, which was higher than our second quarter of 2020, primarily due to the remeasurement of our deferred tax liabilities, primarily as a result of an increase in the U.K. statutory tax rate that will be effective in 2023. Net cash provided by operating activities was $2 billion in the second quarter of 2021.
Excluding the favorable impact from the change in working capital of $1.1 billion and our joint venture partner's 50% share of Diamond Green Diesel's net cash provided by operating activities, excluding changes in DGD's working capital, adjusted net cash provided by operating activities was $809 million. With regard to investing activities, we made $548 million of total capital investments in the second quarter of 2021, of which $252 million was for sustaining the business, including costs for turnarounds, catalysts and regulatory compliance and $296 million was for growing the business.
Excluding capital investments attributable to our partner's 50% share of Diamond Green Diesel and those related to other variable interest entities, capital investments attributable to Valero were $417 million in the second quarter of 2021. Moving to financing activities. We returned $401 million to our stockholders in the second quarter of 2021 through our dividend, resulting in a payout ratio of 50% of adjusted net cash provided by the operating activities for the quarter. Earlier this month, our Board of Directors also approved a regular quarterly dividend of $0.98 per share payable in the third quarter.
And as Joe noted, we were able to cover all of our investing and financing activities, which includes our dividend and capital investments in the second quarter with cash provided by operating activities even without the benefit from the cash tax refund and the proceeds from the sale of a portion of our interest in the Pasadena terminal. With respect to our balance sheet at quarter end, total debt and finance lease obligations were $14.7 billion and cash and cash equivalents were $3.6 billion. The debt-to-capitalization ratio, net of cash and cash equivalents was 37%. At the end of June, we had $5 billion of available liquidity, excluding cash. Turning to guidance. We expect capital investments attributable to Valero for 2021 to be approximately $2 billion, which includes expenditures for turnarounds, catalysts and joint venture investments.
About 60% of our capital investments is allocated to sustaining the business and 40% to growth. And over half of our growth capital in 2021 is allocated to expanding our renewable diesel business. For modeling our third quarter operations, we expect refining throughput volumes to fall within the following ranges Gulf Coast at 1.6 million to 1.65 million barrels per day; Mid-Continent at 435,000 to 455,000 barrels per day; West Coast at 250,000 to 270,000 barrels per day and North Atlantic at 450,000 to 470,000 barrels per day. We expect refining cash operating expenses in the third quarter to be approximately $4.45 per barrel. With respect to the Renewable Diesel segment, with the anticipated start-up of DGD two in the middle of the fourth quarter, we expect sales volumes to average one million gallons per day in 2021.
Operating expenses in 2021 should be $0.50 per gallon, which includes $0.15 per gallon for noncash costs such as depreciation and amortization. Our ethanol segment is expected to produce 3.7 million gallons per day in the third quarter. Operating expenses should average $0.43 per gallon, which includes $0.06 per gallon for noncash costs such as depreciation and amortization. For the third quarter, net interest expense should be about $150 million and total depreciation and amortization expense should be approximately $590 million. For 2021, we still expect G&A expenses, excluding corporate depreciation, to be approximately $850 million, and the annual effective tax rate should approximate the U.S. statutory rate.
That concludes our opening remarks. Before we open the call to questions, we again respectfully request the callers adhere to our protocol of limiting each turn in the Q&A to two questions. [Operator Instructions]