MILAN, Nov 22 (Reuters) - Energy group Eni could list up to 30% of its new retail and renewables business in what is likely to be one of Italy's biggest initial public offerings next year.

At a presentation on Monday Eni Chief Executive Claudio Descalzi said between 20% and 30% of the unit, renamed Plenitude, could be listed depending on market conditions.

"The IPO is a cornerstone of our decarbonisation strategy and key to our ongoing transformation," Descalzi said at the unveiling of Plenitude.

Sources close to the matter told Reuters earlier on Monday Eni could sell a bit more than 30% if demand was there.

Eni said last month https://www.reuters.com/business/energy/italys-eni-opts-list-minority-stake-retail-renewable-unit-2021-10-07 it had decided to list a minority stake in Plenitude as part of broader plans to unlock value across its business and fund its shift away from oil and gas. Sources have previously said the unit, created earlier this year, could be worth around 10 billion euros ($11.3 billion).

Some European energy companies, including Spain's Repsol , are looking at selling parts of their green business to raise money to cut debt and fund their transition from fossil fuel.

Plenitude, which has 10 million customers in six countries, will spend 7.8 billion euros ($8.8 billion) to 2025 to help drive core earnings to 1.3 billion euros from 0.6 billion euros this year.

CEO Stefano Goberti said the company aimed to pay a dividend but added the priority would be on growth and keeping a strong balance sheet.

Renewable capacity, mainly solar, will grow to more than 6 gigawatts by 2025 from 1.2 GW this year, mainly in markets where Eni already has a client base.

But the company is also interested in growing its offshore wind business and is looking to Norway, the United States and Italy.

In April Eni's finance head Francesco Gattei said merging its renewable energy and retail operations could create a vehicle with double-digit multiples.

($1 = 0.8873 euros)

(Reporting by Stephen Jewkes and Elisa Anzolin, Editing by Louise Heavens and Emelia Sithole-Matarise)