We continue to expect that our infrastructure and generation investments will drive compound annual growth of 7% to 9% in diluted net operating earnings per share from the midpoint of our narrowed 2021 guidance through 2024.
We also expect to reduce greenhouse gas emissions 90% by 2030.
In the first quarter, we delivered non-GAAP diluted net operating earnings of $0.77 per share.
As you saw in our release, today we narrowed our 2021 non-GAAP diluted net operating earnings guidance to a $1.32 to a $1.36 per share, which represents the upper half of the previous range.
We expect to make approximately $10 billion in capital investments through 2024.
These include annual investments of $1.9 billion to $2.2 billion in growth, safety and modernization programs.
In addition, our investments in renewable generation are now expected to total approximately $2 billion over this period.
As we outlined at our 2020 Investor Day, 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.
Looking at our first quarter 2021 results in slide 4, we had non-GAAP net operating earnings of about $305 million or $0.77 per diluted share compared to non-GAAP net operating earnings of about $291 million or $0.76 per diluted share in the first quarter of 2020.
Looking more closely at our segment three-month non-GAAP results on slide 5, gas distribution operating earnings were about $374 million for the quarter, representing a decline of approximately $18 million versus last year.
Operating revenues, net of the cost of energy and tracked expenses were down about $84 million due to the sale of CMA, partially offset by increased infrastructure program revenues and customer growth.
Operating expenses also net of the cost of energy and tracked expenses were lower by about $66 million, mostly due to the CMA sale and lower employee-related costs, partially offset by increased depreciation and amortization expense.
In our Electric segment, three-month non-GAAP operating earnings were about $91 million, which was approximately $11 million higher than the first quarter of 2020.
This increase was driven primarily by an approximately $9 million increase in operating revenues, net of the cost of energy and tracked expenses due to infrastructure investments and increased customer usage.
Our debt level as of March 31 was about $9.8 billion, of which about $9.1 billion was long-term debt.
The weighted average maturity in our long-term debt was approximately 15 years, and the weighted average interest rate was approximately 3.7%.
At the end of the first quarter, we maintained net available liquidity of about $1.9 billion, consisting of cash and available capacity under our credit facility and other accounts receivable securitization program.
This issuance that received 100% equity credit from all three agencies allows NiSource to capture share price upside and provide timely proceeds for our renewable investment.
In Pennsylvania, the Public Utility Commission approved an annual revenue increase of $63.5 million in the rate case we filed in 2020.
The commission also approved an ROE of 9.86% with rates effective as of January 23 of this year.
This order approves $40 million in upgrades and replacements under way in 2021 and $2.6 million of incremental revenue.
Nearly $950 million in capital investments are planned through 2025 to be recovered through semi-annual adjustments to the existing gas transmission, distribution and storage improvement charge or TDSIC tracker.
In total, we have announced 14 renewable projects which will likely fill the balance of capacity necessary to replace the retiring units at our Schahfer generating station, which continues to track for retirement by May 2023.
All of these updates continue to track on time to retire nearly 80% of our remaining coal-fired generation by 2023 and retire all coal generation by 2028 to be replaced by lower cost, reliable and cleaner options.
The plan is expected to drive a 90% reduction in our greenhouse gas emissions by 2030 and is expected to save our electric customers an estimated $4 billion over 30 years.
The executed agreements we've announced are also within budget, representing approximately $2 billion of renewable generation investments.
With last month's convertible issuance, NiSource is well positioned to execute the next stage of our growth plan driven by continued execution of our safety and asset modernization programs as well as our electric generation transition strategy.
We are narrowing our 2021 non-GAAP deluded net operating earnings guidance to $1.32 to $1.36 per share, which represents the upper half of the previous guidance.
We expect to make approximately $10 billion in capital investments through 2024.
These include annual investments of $1.9 billion to $2.2 billion in growth, safety and modernization programs.
In addition, our investments in renewable generation are now expected to total approximately $2 billion over this period.
As we outlined at our 2020 Investor Day, NiSource continues to expect to grow its deluded 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.
In addition, we now have a total of 14 renewable energy projects as part of our Your Energy, Your Future initiative.

Summary:
In the first quarter, we delivered non-GAAP diluted net operating earnings of $0.77 per share.
As you saw in our release, today we narrowed our 2021 non-GAAP diluted net operating earnings guidance to a $1.32 to a $1.36 per share, which represents the upper half of the previous range.
Looking at our first quarter 2021 results in slide 4, we had non-GAAP net operating earnings of about $305 million or $0.77 per diluted share compared to non-GAAP net operating earnings of about $291 million or $0.76 per diluted share in the first quarter of 2020.
With last month's convertible issuance, NiSource is well positioned to execute the next stage of our growth plan driven by continued execution of our safety and asset modernization programs as well as our electric generation transition strategy.