**Step 1: Identify the relevant industry**
Based on the facts provided, "ACEA S.P.A." is an Italian multi-utility operating in electricity, gas, and water. According to the S&P sector descriptions, "Multi-utilities" falls under the "Regulated Utilities" sector. Therefore, we will apply the Regulated Utilities methodology.

**Step 2: Estimate Adjusted_Debt**
Formula: Adjusted_Debt = (reported_debt + leases + pension_deficit + guarantees + hybrid_debt_portion + other_debt_like_items) - eligible_cash

*   **Reported Debt:** Other Noncurrent Financial Liabilities (4,791,979,000) + Other Current Financial Liabilities (285,222,000) = 5,077,201,000 EUR
*   **Leases:** Right-of-use Assets (2023-01-01) = 90,397,000 EUR. Under S&P methodology, operating leases are debt-like. We add the right-of-use asset value as a proxy for the lease liability (assuming IFRS 16 is applied and ROU assets approximate lease liabilities).
*   **Pension Deficit:** Net defined benefit liability. Noncurrent Provisions for Employee Benefits (120,150,000) - Current portion is not explicitly broken out, but the pre-tax remeasurement reserve is -18,234,000 EUR. We will use the noncurrent provision as a proxy for the deficit, adding 120,150,000 EUR.
*   **Guarantees / Hybrids / Other debt-like items:** 0 EUR (not identified in facts).
*   **Eligible Cash:** Disponibilità Liquide e Mezzi Equivalenti (680,820,000 EUR). Under S&P Regulated Utilities methodology, cash is typically netted against debt if there is high confidence of near-term cost recovery.

Adjusted_Debt = 5,077,201,000 + 90,397,000 + 120,150,000 - 680,820,000 = 4,606,928,000 EUR

**Step 3: Estimate Adjusted_EBITDA**
Formula: Adjusted_EBITDA = EBITDA + adjustment_leases + nonrecurring_losses - nonrecurring_gains ± pension_adjustments ± joint_venture_proportional_EBITDA ± other_normalization_adjustments

*   **EBITDA (Reported):** We use the "Gross Profit" (Margine Operativo Lordo) which in Italian accounting represents EBITDA. For 2022, this is 1,305,021,000 EUR. (Alternatively, using Operating Profit + Depreciation & Amortization: 565,851,000 + 625,799,000 = 1,191,650,000, plus Impairment 113,370,000 = 1,305,020,000. The Gross Profit line directly matches).
*   **Adjustment for Leases:** Add back the lease interest/depreciation implied by the lease addition. Standard S&P adds 1/3 of the lease addition to EBITDA as an approximation of the interest expense: 90,397,000 / 3 = 30,132,333 EUR.
*   **Nonrecurring items / Pension / JV:** No specific nonrecurring gains/losses or JV proportional adjustments are detailed enough to override the reported figures.

Adjusted_EBITDA = 1,305,021,000 + 30,132,333 = 1,335,153,333 EUR

**Step 4: Calculate the Adjusted_Debt / Adjusted_EBITDA ratio**
Ratio = Adjusted_Debt / Adjusted_EBITDA
Ratio = 4,606,928,000 / 1,335,153,333 ≈ 3.4496

Rounding to two decimal places:
3.45

<answer>3.45</answer>