In addition, we have received more than 180 proposals in our 2021 integrated resource plan, or IRP process, which will inform our generation replacement strategy in Indiana beyond 2023.
We continue to expect that our infrastructure programs and generation investments will drive compound annual growth of 7% to 9% in diluted net operating earnings per share from 2021 through 2024, while reducing greenhouse gas emissions 90% by 2030 compared to 2005 levels.
In the second quarter, we delivered non-GAAP diluted net operating earnings of $0.13 per share.
We expect 2021 earnings of $1.32 to $1.36 per share in non-GAAP diluted net operating earnings.
We continue to expect annual growth, safety and modernization investments of $1.9 to $2.2 billion, plus approximately $2 billion in renewables and associated transmission investments through 2023.
NiSource expects to grow its diluted net operating earnings per share by 7% to 9% on a compound annual growth rate basis from 2021 through 2024, including near-term annual growth of 5% to 7% through 2023.
As I mentioned, the Indiana Utility Regulatory Commission has approved 13 of our 14 proposed renewable energy projects and the new RFP for electric capacity and energy associated with NIPSCO's 2021 IRP, that is currently underway, has drawn strong engagement from the vendor community.
We expect to reduce total greenhouse gas emissions 90% by 2030 from 2005 levels.
That includes a 50% reduction in methane emissions from gas mains and services by 2025.
On that commitment, NiSource has already achieved an estimated 39% reduction in pipeline methane emissions compared to 2005 levels.
We are requesting an annual revenue increase of approximately $221 million, net of the trackers being rolled into base rates.
In Kentucky, we filed a request for an approximately $27 million annual revenue increase net of trackers.
And in Maryland, we filed a case on May 14, once again, net of trackers, requesting about a $5 million annual revenue increase.
In Pennsylvania, we filed a case just before the end of the first quarter, requesting an annual increase in revenue of approximately $98 million.
The $1.6 billion plan includes newly identified projects aimed at enhancing service and reliability for customers as well as some previously identified projects.
This brings NIPSCO to the verge of an important milestone with 13 of 14 renewables projects approved to advance and replace the retiring capacity of the Schahfer generating station.
Combining these new generating facilities with a number of transmission projects to support system reliability across the new footprint, NiSource continues to track toward approximately $2 billion of renewable generation investments through 2023.
We are excited these projects will produce clean, reliable power for our communities, while saving NIPSCO customers approximately $4 billion over the long term.
Furthermore, with these more than 180 proposals covering a wide range of technologies and ownership constructs, it continues to point to a robust market across generation technologies, which will drive value for our customers and stakeholders.
Any specific projects then identified, which support this preferred plan would represent incremental projects beyond the 14 highlighted earlier and in addition to the approximately $2 billion in renewable investments NIPSCO has already filed.
Looking at our second quarter 2021 results on slide four, we had non-GAAP net operating earnings of about $53 million or $0.13 per diluted share compared to non-GAAP net operating earnings of about $50 million or $0.13 per diluted share in the second quarter of 2020.
Gas distribution [Technical Issues] operating earnings were about $66 million for the quarter, representing a decline of approximately $8 million versus last year [Technical Issues] down about $28 million due to the sale of CMA [Technical Issues] upward in expenses also [Technical Issues] offset by higher employee related [Technical Issues] costs and outside services [Technical Issues], which was nearly $5 million lower than the second quarter of 2020.
Operating revenues rose about $11 million, net of the cost of energy and tracked expenses due to infrastructure investments and increased customer usage.
Operating expenses, net of the cost of energy and tracked expenses were up about $16 million due to generation related maintenance and employee related costs.
Our debt level as of June 30 was about $9.2 billion, of which about $9.1 billion [Technical Issues] was long term debt [Technical Issues] in years, and the weighted average interest rate was approximately 3.7%.
At the end of the second quarter, we maintained net available liquidity of about $2.2 billion, consisting of cash and available capacity under our credit facility and our accounts receivable securitization programs.
As Joe mentioned in our key takeaways, we are reaffirming our 2021 earnings guidance and long term financial commitments.

Summary:
In the second quarter, we delivered non-GAAP diluted net operating earnings of $0.13 per share.
We expect 2021 earnings of $1.32 to $1.36 per share in non-GAAP diluted net operating earnings.
We continue to expect annual growth, safety and modernization investments of $1.9 to $2.2 billion, plus approximately $2 billion in renewables and associated transmission investments through 2023.
Looking at our second quarter 2021 results on slide four, we had non-GAAP net operating earnings of about $53 million or $0.13 per diluted share compared to non-GAAP net operating earnings of about $50 million or $0.13 per diluted share in the second quarter of 2020.
As Joe mentioned in our key takeaways, we are reaffirming our 2021 earnings guidance and long term financial commitments.