Step 1 — Relevant industry  
ACEA S.p.A. is a multi-utility group with regulated utility activities, including water, electricity distribution, public lighting, and energy infrastructure/services. The most relevant methodology provided is therefore **Regulated Utilities**. The FFO-to-debt ratio is a core financial metric under the regulated utility framework.

Step 2 — Estimate Adjusted EBITDA  
The facts provide:

- Gross Profit / EBITDA-like measure for 2022: **€1,305,021,000**
- Cash flow statement depreciation and amortisation adjustment: **€594,636,000**
- Operating profit: **€565,851,000**

Reported EBITDA can be checked as:

\[
EBITDA \approx Operating\ Profit + D\&A + impairment/provisions
\]

The annual report’s “Gross Profit” appears to represent EBITDA/MOL, so I use:

\[
Adjusted\ EBITDA \approx 1,305,021,000
\]

No explicit data are provided for S&P lease capitalization add-back, nonrecurring items, guarantees, or proportional JV EBITDA adjustments. Right-of-use assets and lease liabilities are not separately disclosed as debt, so no additional lease adjustment is made beyond the company’s IFRS presentation.

\[
Adjusted\ EBITDA = €1,305.021m
\]

Step 3 — Estimate FFO  
Baseline formula:

\[
FFO = Adjusted\ EBITDA - cash\ interest - cash\ taxes
\]

Given:

- Interest paid classified as financing activities: **€114,121,000**
- Income taxes paid: **€178,506,000**

\[
FFO = 1,305,021,000 - 114,121,000 - 178,506,000
\]

\[
FFO = 1,012,394,000
\]

So:

\[
FFO = €1,012.394m
\]

Step 4 — Estimate Adjusted Debt  
Reported financial debt is approximated from financial liabilities:

- Other noncurrent financial liabilities: **€4,722,263,000**
- Other current financial liabilities: **€619,418,000**

\[
Reported\ debt = 4,722,263,000 + 619,418,000 = 5,341,681,000
\]

Eligible cash:

- Cash and cash equivalents at year-end 2022: **€559,908,000**

No sufficient detail is provided for S&P haircuts to surplus cash, pension deficit add-ons, guarantees, or hybrid instruments. Therefore:

\[
Adjusted\ Debt = 5,341,681,000 - 559,908,000
\]

\[
Adjusted\ Debt = 4,781,773,000
\]

Step 5 — Calculate FFO / Adjusted Debt  

\[
FFO / Adjusted\ Debt = \frac{1,012,394,000}{4,781,773,000}
\]

\[
= 0.2117
\]

<answer>0.2117</answer>