* To start work on first leg of hydrogen backbone in 2025

* Tests show its gas storage sites can hold 100% hydrogen

* Core earnings to grow 6-8% 2022-2030

* To cut emissions of associate companies by 46% by 2030

*

MILAN, Nov 29 (Reuters) - Europe's biggest gas pipeline group Snam has pencilled in 23 billion euros ($26 billion) of investments over the next nine years to ready its network for hydrogen and the energy transition.

The company said it was looking to spend around 3 billion euros to re-purpose 2,700 km of network to transport green hydrogen from Africa and the south of Italy northwards to high-energy demand regions like Germany.

Work will start on the first leg of the hydrogen backbone in 2025 and is expected to be completed before 2030, Snam CEO Marco Alvera said in a call on the group's new strategy plan.

Snam, which makes most of its revenue from gas transport in Italy, is keen to develop the use of hydrogen in its pipelines as economies wean themselves off fossil fuels to meet climate targets.

"We will play a key role in a decisive decade for the energy transition, aiming to seize new growth opportunities in Italy and internationally," Alvera said.

On Saturday Snam agreed to buy a stake in pipelines carrying Algerian gas https://www.reuters.com/business/eni-agrees-sell-snam-499-stake-algeria-gas-pipelines-385-mln-euros-2021-11-27 into Italy in a move that could lay the groundwork for green hydrogen imports from Africa into Europe.

The group, which manages some 33,000 km of pipeline in Italy, said it could spend 12 billion euros to 2030 on upgrade its domestic grid, already 99% ready to carry unblended hydrogen.

"Italy's ambition is to become a hydrogen hub for Europe importing green hydrogen from North Africa and exporting it to the north," Alvera said.

Hydrogen today is too expensive for widespread use but as costs come down governments round the world are looking to it to replace fossil fuels in sectors where electrification is not an easy solution.

GREEN STORAGE

Green hydrogen is produced from wind and solar power by using electrolysers. Alvera said Snam was ready to back plans by Italian firm De Nora, in which it has a stake of around 36%, to build an electrolyser Gigafactory.

"The factory will have a capacity of more than 1 giga," Alvera said, adding De Nora could list next year.

Snam, which runs most of Italy's gas storage capacity, said it planned to spend up to 5 billion euros to 2030 on energy storage, including developing an international green energy storage platform.

Italy is one of the European countries that has urged the EU to build joint strategic sites to store gas to help mitigate supply and prices.

Some European countries could face gas shortages this winter if temperatures drop sharply because their storage sites are understocked.

"We have no plans to list the business," Alvera said, adding tests showed Snam's current gas storage sites could be used to store 100% hydrogen.

Snam said the investments in its plan would help drive its earnings from next year to the end of the decade by 6-8% per year as it looks to become net carbon neutral for its own operations by 2040.

The company, which pledged to spend 8.1 billion euros in the four years to 2025, confirmed a 5% growth in dividends to 2022 with a minimum growth of 2.5% per year to 2025. ($1 = 0.8857 euros) (Reporting by Stephen Jewkes, editing by Giulia Segreti and David Evans)