Let me also remind you that CVR Partners completed a 1-for-10 reverse split of its common units on November 23, 2020.
Yesterday, we reported the second quarter consolidated net loss of $2 million and a loss per share of $0.06.
Adjusted EBITDA for the quarter was $66 million.
However, once again, rising RIN prices were considerable headwinds to our results, including a $58 million non-cash mark-to-market on our estimated outstanding RIN obligation.
In May, our Board of Directors approved a special dividend totaling $492 million, comprised of a combination of cash and our interest in Delek US Holdings.
In addition to providing shareholders with nearly $5 per share of cash and Delek stock, this structure also allowed us to recognize a net gain of $87 million that we made on our Delek investment, while providing us with an efficient exit.
For our petroleum segment, the combined total throughput for the second quarter of 2021 was approximately 217,000 barrels per day, as compared to 156,000 barrels per day in the second quarter of 2020, which was impacted by a planned turnaround at Coffeyville.
The Group three 2-1-1 crack averaged $19.15 per barrel in the second quarter as compared to $8.75 in the second quarter of 2020.
On a 2020 RVO basis, RIN prices averaged approximately $8.15 per barrel in the second quarter a 267% increase, from the second quarter of 2020.
The Brent-TI differential averaged $2.91 per barrel in the second quarter as compared to $5.39 in the prior year period.
The Midland Cushing differential was $0.24 over WTI in the quarter as compared to $0.40 per barrel over WTI in the second quarter of 2020.
And the WCS to WTI differential was $12.84 compared to $9.45 in the same period last year.
Light product yield for the quarter was 99% on crude processed.
In total we gathered approximately 118,000 barrels a day of crude oil during the second quarter of 2021 compared to 82,000 barrels per day in the same period last year, when production levels were disrupted by low crude oil prices at the onset of the COVID pandemic.
In the Fertilizer segment both plants ran well during the quarter with consolidated ammonia utilization of 98%.
USDA estimates for corn planting and yields continues to imply one of the lowest inventory carryouts in the last 10 years.
For the second quarter of 2021, our consolidated net loss was $2 million loss per diluted share was $0.06 and EBITDA was $102 million.
Our second quarter results include a negative mark-to-market impact on our estimated outstanding rent obligation of $58 million, unrealized derivative gains of $37 million, favorable inventory valuation impacts of $36 million and a mark-to-market gain of $21 million related to our investment in Delek.
Excluding these items, adjusted EBITDA for the quarter was $66 million.
The Petroleum segment's adjusted EBITDA for the second quarter of 2021 was $18 million compared to negative $1 million in the second quarter of 2020.
In the second quarter of 2021 our Petroleum segment's reported refining margin was $6.72 per barrel.
Excluding favorable inventory impacts of $1.81 per barrel, unrealized derivative gains of $1.87 per barrel and the mark-to-market impact of our estimated outstanding RIN obligation of $2.92 per barrel, our refining margin would have been approximately $5.99 per barrel.
On this basis capture rate for the second quarter of 2021 was 31% compared to 75% in the second quarter of 2020.
RINs expense excluding mark-to-market impact reduced our second quarter capture rate by approximately 30%.
Derivative losses for the second quarter of 2021 totaled $2 million, which includes unrealized gains of $37 million primarily associated with crack spread derivatives.
In the second quarter of 2020, we had total derivative gains of $20 million, which included unrealized gains of less than $0.5 million.
In total RINs expense in the second quarter of 2021 was $173 million or $8.77 per barrel of total throughput compared to $16 million or $1.12 per barrel for the same period last year, an increase of over 680%.
Our second quarter RINs expense was inflated by $58 million from the mark-to-market impact on our estimated RFS obligation, which was mark-to-market at an average RIN price of $1.67 at quarter end.
For the full year 2021, we forecast an obligation based on the 2020 RVO levels of approximately 255 million RINs.
This includes RINs generated from internal blending and approximately 19 million RINs we could generate from renewable diesel production later this year, but does not include the impact of expected waivers.
The petroleum segment's direct operating expenses were $4.23 per barrel in the second quarter of 2021 as compared to $5.52 per barrel in the prior year period.
For the second quarter of 2021, the fertilizer segment reported operating income of $30 million, net income of $7 million or $0.66 per common unit and adjusted EBITDA of $51 million.
This is compared to second quarter 2020 operating losses of $26 million, a net loss of $42 million or $3.68 per common unit and adjusted EBITDA of $39 million.
The partnership declared a distribution of $1.72 per common unit for the second quarter of 2021.
As CVR Energy owns approximately 36% of CVR Partners' common units, we will receive a proportionate cash distribution of approximately $7 million.
Total consolidated capital spending for the second quarter of 2021 was $83 million, which included $9 million from the petroleum segment, $4 million from the fertilizer segment and $69 million on the renewable diesel unit.
Environmental and maintenance capital spending comprised $12 million, including $8 million in the petroleum segment and $3 million in the fertilizer segment.
We estimate total consolidated capital spending for 2021 to be approximately $226 million to $242 million, of which approximately $83 million to $91 million is expected to be environmental and maintenance capital.
Our consolidated capital spending plan excludes planned turnaround spending, which we estimate will be approximately $7 million for the year in preparation for the planned turnaround at Wynnewood in 2022 and Coffeyville in 2023.
Cash provided by operations for the second quarter of 2021 was $147 million and free cash flow was $54 million.
Working capital was a source of approximately $100 million in the quarter due primarily to an increase in our estimated RINs obligation, partially offset by a decrease in derivative liabilities and increased crude oil and refined products inventory valuation.
Subsequent to quarter end, we received an income tax refund of $32 million related to the NOL carryback provisions of the CARES Act.
At June 30th, we ended the quarter with approximately $519 million of cash.
As a reminder the cash portion of the second quarter special dividend paid on June 10 was $242 million.
Our consolidated cash balance includes $43 million in the fertilizer segment.
As of June 30th, excluding CVR Partners, we had approximately $652 million of liquidity, which was comprised of approximately $483 million of cash and availability under the ABL of approximately $364 million less cash included in the borrowing base of $195 million.
Looking ahead to the third quarter of 2021 for our petroleum segment, we estimate total throughput to be approximately 190,000 to 210,000 barrels per day.
We expect total direct operating expenses to range between $75 million and $85 million and total capital spending to be between $18 million and $24 million.
For the fertilizer segment, we estimate our third quarter 2021 ammonia utilization rate to be greater than 95%, direct operating expenses to be approximately $38 million to $43 million, excluding inventory impacts and total capital spending to be between $9 million and $12 million.
While benchmark cracks increased nearly $3 per barrel during the second quarter, RIN prices increased by nearly the same amount, leaving the underlying margin available to refineries mostly unchanged.
As we near the completion of Phase one of our renewable diesel strategy, we continue to develop Phase 2, which involves adding pretreatment capabilities for low-cost and lower-CI feedstocks.
The Group 3 2-1-1 cracks have averaged $18.75 per barrel with RINs averaging $7.77 on a 2020 RVO basis; the Brent-TI spread has averaged $1.72, with the Midland Cushing differential at $0.14 under WTI and the WTL differential at $0.68 under Cushing WTI, and the WCS differential at $13.04 per barrel under WTI; ammonia prices have increased to around $600 a ton, while UAN prices are over $300 a ton.
As of yesterday, Group 3 2-1-1 cracks were $20.84 per barrel Brent-TI was $1.63 and the WCS differential was $14.45 under WTI.
On the 2020 RVO basis RINs were approximately $8.40 per barrel.
It should also implement a 95 octane standard for all new ICE engines internal combustion engines.

Summary:
Yesterday, we reported the second quarter consolidated net loss of $2 million and a loss per share of $0.06.
For the second quarter of 2021, our consolidated net loss was $2 million loss per diluted share was $0.06 and EBITDA was $102 million.